The seas’ most sought-after fish are swimming between a rock and a hard place: the fisherman’s net and an encroaching mass of suffocating water.

A recent study has uncovered a new dose of bad news for ocean fish and the fishing industry. Areas of the deep ocean with little dissolved oxygen, called dead zones, are expanding and, thus, shrinking many fishes’ watery homes.

One driving force behind the predicament is none other than that pesky climate problem.

“Climate change is actually working in tandem with overexploitation of the animals to push these populations into a real dangerous place in terms of population collapse,” said Eric Prince, a fisheries biologist with the National Oceanic and Atmospheric Administration’s Southeast Fisheries Science Center and co-author of the study.

For example, Prince and his colleagues calculated that the Atlantic blue marlin, an economically valuable fish that was a focus of their study, has lost about 15 percent of its habitat from expanding dead zones since 1960. Dwindling habitat threatens not only the lives of fishes, but also the sustainability of the already ailing fishing industry.

Breathing room

Like their above-water brethren, fish need oxygen, which is dissolved in the water. Big, predatory fish, such as the blue marlin, need more dissolved oxygen than most, because they require lots of energy to grow and survive. Without sufficient oxygen, they’ll suffocate.

The level of oxygen in the water thus partly delineates fish habitat boundaries. Dead zones often draw these borders.

As climate change causes open ocean dead zones to balloon, fish habitat deflates.

Diagram modified from one originally published in Deep Sea Research Part I: Oceanographic Research Papers, Vol 57, Issue 4, Lothar Stramma, Sunke Schmidtko, Lisa A. Levin, & Gregory C. Johnson. Ocean oxygen minima expansions and their biological impacts, 587-595, Copyright Elsevier (2010).

Technically known as oxygen minimum zones, dead zones are actually a natural occurrence. Found at depths of between 200 and 1000 meters, they are caused partly by seawater circulation and partly by the decomposition of organic matter, namely deceased sea critters that sink from surface waters.

As aerobic bacteria nosh on the organic matter, they use up the oxygen in the water. Eventually, hypoxia happens—the water becomes so depleted of oxygen that many creatures can’t survive.

Since deep-sea dead zones are insulated from the ocean’s surface, where the water borrows oxygen from the atmosphere, they can only reload with oxygen if currents make a long-distance delivery, according to Sunke Schmidtko, an oceanographer at the University of East Anglia, the other co-author of the study.

Deep-sea dead zones are different from their coastal cousins like the one in the Gulf of Mexico. Coastal dead zones form due to a buildup of agricultural fertilizer that rivers, such as the Mississippi, collect and then flush out to sea, causing abnormal blooms of plant life.

De-fizzing the ocean

But climate change is turning what Mother Nature does normally into a big problem. As the air is getting hotter, so is the water, and warmer water can hold less oxygen than colder water.

This is similar to what happens to a soft drink on a hot day. After sitting in the heat and sun, the fizz fizzles, and you are left with a flat, carbon dioxide-depleted beverage.

Also, warmer surface waters are less likely to sink to the ocean’s lower layers, because warm water is lighter than the colder water below, Schmidtko explained. In other words, as the oxygen-rich surface layers heat up, they could have a harder time delivering oxygen to the deeper ocean.

Schmidtko clarified that oceanographers are still trying to determine how exactly climate change is affecting the ocean, but with their knowledge of how water works, these represent their current speculations.

The rock below

With less oxygen to go around, oxygen minimum zones are swelling and intruding on many fishes’ living zones.

For example, marlins often dive deep to feed, sometimes as far down as 800 meters. However, in the eastern Atlantic’s growing dead zone, which is already one of the largest in the world, Prince found that marlins can’t dive as deep as their west-side counterparts.

“They need to go where the food is and where they can breathe,” he said.

With less breathing room below, the floor of their habitat rises, and they are pinned to the surface layers. With nowhere to go but up, marlins become squished into tighter, testier quarters with other predatory fish and their prey. They also find it harder to dodge a waiting fishing hook or net.

“Concentrating them makes it much easier for overexploitation by [humans],” said Prince.

The increasing concentration of animals at the top could also lead to a boost in the amount of sinking organic matter, which would further worsen the oxygen shortage below.

Softening the hard place above

As a prized catch, Atlantic blue marlins are already victims of overharvesting. In fact, their populations have dropped 60-64 percent over the past three fish generations (14-18 years).

But the growing dead zones can actually fool scientists and fishermen into thinking fish populations are doing just fine, since more fish are squeezed into a smaller area. Thus, to ensure the dead zone-fishing vise does not become their demise, Prince said scientists must more carefully monitor fish populations, as well as the expansion of the dead zones.

While fish stock assessments are starting to incorporate this information, Prince warned the pace needs to quicken.

And if the Earth is to continue warming, as most scientists predict, Schmidtko added that humans should chill out on fishing.

After all, we will never be capable of “ventilating the ocean,” he said.

Astronomers have just discovered two Earth-size, rocky planets around a nearby star. Though the planets are way too broilsome for life, they suggest that steady improvements in telescope technology has made the discovery of habitable planets just a matter of time.

But as astrobiologists continue to search for life in space, geo-biologists (ok, we coined that) continue to find bizarre life in strange places on Earth: in the dark ocean depths, between grains of sand, and at roasty-toasty temperatures once considered deadly.

Hot, humid, and totally alive!

Fifty years ago, nobody believed organisms could survive near the boiling point of water. When Thomas Brock started probing the hot springs in Yellowstone in the 1960s, he was not looking to overthrow a ground rule of biology. Instead, the University of Wisconsin-Madison professor, then at Indiana University, sought to study bacteria in a simplified, real-world environment.

At the time, and even today, precious little was known about how bacteria live their lives — unless they cause disease.

As Brock sampled his way up a hot stream, he approached its source in a hot spring, and the water temperature rose steadily.

At the time, biologists thought life would not tolerate temperatures near 80° C. But Brock kept finding bacteria, so he kept looking. Eventually, he found some that could live and reproduce near the temperature of boiling water — 100° C.

The prize of his collection was a bacterium he named Thermus aquaticus (for its hot-water habitat) and placed in a public repository for study by other scientists.

Over the years, T. aquaticus proved interesting indeed. For one thing, it was the first of more than 50 species of thermophilic bacteria known to tolerate or require temperatures near water’s boiling point.

For another, it was the first of the Archaea (ancient ones), primitive microorganisms that scientists now regard as a separate and highly primitive kingdom of life.

Deep roots indeed

Because thermophiles are Archaeans, and prefer the steamy conditions typical of early Earth, many scientists think they may tell us about the origin of life itself.

To any basic scientist, those contributions would be enough. But because their enzymes work in high temperatures, where chemical reactions are faster, the thermophiles have proven to be extraordinarily useful.

Today, enzymes derived from thermophiles are used to convert millions of pounds of corn (maize) into sugar to sweeten soft drinks.

But more important, at least to scientists who don’t guzzle fizzy pop at the lab bench, T. aquaticus supplied TAQ polymerase, the essential enzyme for polymerase chain reaction, AKA PCR.

PCR is an artificial technique that does what living critters do every day — replicate DNA. But PCR is the rocket ship of replication, since it allows you to multiply a piece of DNA a billion times in a few hours. That produces enough DNA to analyze to your heart’s content — for genetic engineering, biotechnology and forensic purposes.

PCR depends on TAQ polymerase.

Aware that PCR and soda pop are both billion-dollar industries, corporations and scientists around the world have frantically searched for other thermophiles that may have equally useful enzymes. They’re looking in odd places — not just hot springs and volcanoes, but also deep-sea vents, hot petroleum-bearing rock, the outflow of geothermal power plants, and smoldering piles of garbage.

Prowling for glow-in-the-dark squid

Call me Bob.

Short for bobtail squid. (Did I mention that I’m a 3-4 centimeter cephalopod, formally Euprymna Scolopes?)

Anyway, I hang out in shallow waters around Hawaii. Save your crocodile tears — somebody’s got to live in the sunny, tropical ocean. Anyway, here’s my problem: Even though I have 10 tentacles, I don’t have spines, poisons, or any other decent defense.

So I spend my days burrowed in sand at the ocean bottom, trying to keep out of mischief. Still, a fellow’s got to eat, don’tcha know, so I cruise at night, looking to grab a bite.

Here’s the snag: All sorts of nocturnal predators seem to have this thing about calamari sushi.

Light before flashlights

A long time ago, my ancestors evolved a nifty defense against their big teeth: stealth. Even their tiny squid brains figured out that predators could see them from below, as tasty dark blobs against the bright ocean surface.

Since this was before flashlights, my relatives had to improvise. So they press-ganged billions of luminescent bacteria into making light for them. The idea was to make us just as bright as the ocean surface — and hence invisible.

At least, this is how my great-aunt Tentacla tells it. To tell the truth, I think it had more to do with the evolutionary advantage of being hard to see.

Anyway, my ancestors fed the bacteria, and gave them a home in two specialized light-emitting organs. These “photophores” have a reflective membrane to shine all their light down, toward the hungry predators. They use a diaphragm to control brightness, and even have a lens to spread the light.

The photophore reminds me of a backwards eye — one that makes light rather than detects it.

My folks even figured out how to switch the bacteria “on” when needed.

In return, the bacteria got room and board, in the biological deal they call “symbiosis” or “mutualism.” Sometimes I think people could learn from this cooperative spirit….

But that’s enough thinking for today. My squid brain is squashed.

As I burrow into the sand for another daytime nap, permit me to introduce somebody who considers me almost as fascinating as I do.

Seriously speaking…

Margaret McFall-Ngai, a biologist at University of Wisconsin-Madison, says the bobtail squid may pretend it’s cooperating in a symbiosis with those light-making bacteria, but the reality is more ominous.

She says there’s evidence that this may be slavery, not symbiosis, since the squid, “inhibits the growth of the bacteria to enhance their luminescence.” The bacteria, Vibrio fischeri, could make a better living drifting in the ocean, or in the gut of another marine animal, McFall-Ngai observes.

The concept of bacterial enslavement broadens our perspective on the many possible relationships in the living world.

Most people, if they think about bacteria at all, conjure up disease and decay, but people would be dead without bacteria, since the little critters play essential roles in producing vitamins and preventing disease.

Since the bacteria in our guts vastly outnumber the cells in our bodies, it helps that they’re helpful!

Nevertheless, and for understandable reasons, bacteriologists have traditionally focused on disease-causing organisms, and, for simplicity, on one species at a time. But that skews our view of how bacteria actually live, says McFall-Ngai.

Three cheers for complexity!

Complexity and subtlety may be the hallmarks of these interactions, and the complexity begins by recognizing that V. fischeri is closely related to V. cholerae, which causes the human intestinal disease, cholera.

Cholera is caused by a V. cholera toxin similar to a toxin produced by the light-emitting bacterium. But far from harming the poor little bobtail, that toxin signals it to secrete food for V. fischeri, so the toxin is really a chemical “dinner bell.”

And this raises the intriguing notion that a cholera bug secretes toxins not to kill its host but to discuss its menu. If so, our whole notion of pathogenesis may need rewriting, McFall-Ngai suggests. “Maybe when we’ve been studying cholera pathogenesis we’ve been studying an aspect of a normal conversation that’s gone wrong.”

Indeed, the traditional bacteriological view of bacteria as pathogens to be studied in pure culture may be “like trying to understand the complexity of all the cultures that lived in Paris by studying the activity of the Nazi occupiers,” McFall-Ngai suggests. “You are studying groups that don’t belong there, and have disrupted the normal activities.”

Want more on how the flashlight squid bullies its bacterial brethren?

Between the grains

(1996 story, only photos have been updated)

To zoologist Robert Higgins, small is beautiful. His infatuation with small creatures — “meiofauna” — dates to a student job in a biology lab that paid 35 cents an hour. Instead of quitting for more lucrative work, Higgins was intrigued.

He’d heard about tiny, amazingly diverse creatures, and put grains of sand and muck through a fine mesh, and used a microscope to find hundreds of organisms.

Forty-four years later, Higgins has retired from the Smithsonian Institution, but he’s still goggling at meiofauna — a complex group of animals found in most Earthly environments.

Indeed, a handful of wet sand could contain more biological diversity than a whole rain forest, Higgins says.

In the course of peering through countless microscopes, Higgins has discovered hundreds of species. With Danish biologist Reinhardt Kristensen, he found an entire phylum, called Loricifera.

Phyla are the broadest categories of organisms, based on structure, and according to the International Association of Meiobenthologists, “The majority of recognized phyla have meiofaunal representatives. Currently, 20 phyla considered to be meiofaunal from the 34 recognized phyla of the Kingdom Animalia. Out of these 20 phyla, five are exclusively meiofaunal in size.”

Photo: Giulio Melone, department of biology, Milan University.

A bdelloid (a type of meiofauna) shrinks when it undergoes anhydrobiosis. The dormant, dehydrated bdelloid has greater resistance to environmental stress but is ready to spring back to the active form in conducive conditions.

Meiofauna living between grains of sand have made some fancy adaptations to their harsh environment. Some have hooks on their feet, used to grab the sand. Others have hooked mouthparts, also useful for locomotion.

Beyond freeze-dried

To survive a difficult environment, meiofauna called tartigrades have evolved an amazing adaptation called “anhydrobiosis.” In this form of suspended animation, the animals replace water in their cell membranes with sugar, protecting the membrane from destruction through radiation and freezing. Microorganisms die when their cell membrane ruptures.

During anhydrobiosis, organisms are rather like plant seeds or bacterial spores, Higgins explains. “They can dry up for 100 years, and be rewetted, and come right back to active metabolism.”

Fun is fun. But what is the practical importance of studying stuff that can hardly be seen, doesn’t seem to cause disease, and is — at least to some — utterly ugly?

In other word, who cares about microscopic beach crud?

Meet the beach-cleaning crew

Anybody who likes to hang on the sand should be interested, Higgins says. “This is the system that helps keep our beaches clean.” Plankton, bacteria, all sorts of dead material is continually washing ashore, and a lot of people love to sit on beaches.

There’s a public-health angle here. Hookworms occur on beaches where dogs defecate, but meiofauna may consume hookworms, along with other nematodes. “So if we upset that, we could upset beach cleanliness,” Higgins says.

Higgins notes that meiofauna comprise a basic part of the food web, and disturbing them could have unforeseen consequences for the entire system.

Still, it’s hard to escape the notion that most of the motivation here is the pure scientific urge to discover, to classify, to understand. Meiofauna, Higgins notes, were seen under the microscope Anton van Leeuwenhoek invented in 1683.

The key to finding these things, Higgins indicates, in patience, technology, curiosity — and institutional support. “If you stare through a microscope for hour after hour, you have a chance of finding these things, but if you need to get out a certain number of papers each year, you have to take shortcuts and you won’t find as much.”

Fantastic freak show

If you’ve hung around a big-city park, you may think that pigeons are countless — or uncountable. But according to scientists from New Zealand, pigeons now join the short list of animals that can count — or at least, can places images containing two countable items in numerical order.

It’s blue news for those who think only humans deserve human capacities. From empathy and altruism to murder and war, animals seem to have caught on to some of our best — and worst — tricks.

Now Damian Scarf, a post-doctoral researcher at the University of Otago, with his colleagues, has taught three pigeons to order pairs of numbers in the range from one through nine.

This is not exactly counting, but it certainly is a sign of numerical awareness in birds.

More important, the researchers have taught these retired racing pigeons the concept of smaller-to-larger, Scarf says. “Previously, this number abstraction was only known in primates, and now we have shown that it is not unique to primates.”

Serious screen-time serves science

The experiment began with a year-long training period, during which the birds were shown pairs of images, each containing one, two or three countable items. If the birds pecked at both images, smaller number first, they were rewarded with some wheat. (Although the images never contained a numeral, we refer to the “number” they contain for brevity.)

To prevent the birds from focusing on color, shape or other non-numerical details, the images showed a range of items, so that the only correct answer would reflect their number rather than other distinctions.

“The training time reflects how difficult it is for them to abstract,” Scarf says. “It’s such a foreign situation, number is not the first port of call when presented with a stimulus to discriminate. That’s why we had so many shapes, colors, surface areas.”

Even if the birds originally made their judgments based on color, “we pushed them to use a different strategy, to break away from that. Number is not the default discrimination mechanism” for pigeons, says Scarf, who worked under advisor Michael Colombo of Otago.

A genius for abstraction?

This does not mean that the birds are counting, says Scarf. “It’s more a fuzzy representation in the brain of what ‘three’ is. We can apply this verbal label to three, but they cannot. Pigeons, and animals in general, don’t have a definite idea of a number, that’s why they don’t perform perfectly, and why we see the distance effect.”

When the numbers on the test pair are further apart, Scarf found, “the fuzziness overlaps a little less.”

A greater distance between the numbers produced a quicker response and greater accuracy. For adjacent numbers, like four and five, the birds scored about 66 percent accuracy, compared to more than 95 percent for numbers separated by at least six. Once the difference rose to at least three, the pigeons did as well as monkeys in a path-breaking 1998 study that opened the field of numerical “thinking” in animals.

Scarf stresses that the birds were not just regurgitating what they had learned, but were learning numerical rules. “The goal was to find out whether they could acquire an abstract rule. We were just training for one through three, but they learned some flexibility, an abstract, ascending rule for ordering numbers” that would apply to other numbers on the screen.

Rooted in evolution, but where?

Being able to recognize that one thing is more numerous than another could help an animal survive, Scarf says. “When food is available in multiple places, an animal has to develop an optimal strategy for figuring out where the most food is, and I think we have subverted that capacity for this task.”

Where this capacity arose is anybody’s guess at this point. The evolutionary lineage of mammals and birds divided about 300 million year ago, Scarf says. “If this derived from a common ancestor, it’s very old. It’s also possible that primates and birds have evolved this independently.”

“I do think it’s important, just as our study of mirror self-recognition in monkeys, from the fundamental standpoint of how these abilities come about,” says Luis Populin, a professor of anatomy at the University of Wisconsin-Madison, who has found that, under certain conditions, monkeys can recognize themselves in a mirror. “It’s very nice and is yet another step toward understanding how our cognitive functions develop.”

You have to hand it to these birds, which have set a new standard for avian aptitude. “The new part is the idea that this abstraction of numbers is not tied to training,” says Scarf. “Most numerical tests with animals involve training and testing with the same numbers, but we were training with a limited set of numbers and testing them with numbers outside the range. They learned an abstract rule, and that’s what makes this study unique.”

If you drop a worker ant from an Amazonian treetop, what happens? In the species Cephalotes atratus, 87 percent of the time, that ant will wind up back where it started — a few meters lower down the same tree. Drop things that drift down at random, and only 5 percent of them will hit the tree.

In other words, these ants are controlling their flight — even though they don’t have wings.

That finding, which Stephen Yanoviak, Robert Dudley and Michael Kaspari¹ reported in 2005, provides a great starting point for untangling one of the mysteries of biology:

When and how did so animals take to the air?

Fly high

Flight is pretty common — among critters with wings, or something that resembles them, like a stretched membrane of skin. Birds, bats, moths and butterflies can fly. Even some lizards, snakes, fish and squirrels can glide under control toward the ground, which is not the same thing as falling.

Studies of ants in South America provide good data on “controlled aerial descent,” says Dudley, a professor of integrative biology at the University of California at Berkeley. In the course of some rather entertaining research, he and his colleagues have found that Cephalotes atratus ants:

During the controlled descent, at speeds above 4 meters per second, the ants perform “rapid postural adjustments,” Dudley says. “The limbs are moving, it’s not like a paper airplane.”

Dudley, an expert in the biomechanics of flight, says hundreds of species of tree-living ants in tropical Amazonian forests have evolved controlled gliding. Dropping to the forest floor can make them a meal for a mean and hungry ground-dwelling ant.

Looking at evolution

Perhaps the coolest part of the story is its evolutionary angle. Previously, scientists intrigued by the origin of flight have looked for evidence of wings and feathers, which appear more than 100 million years back in the fossil record.

But if flight really originated in arthropods that could not survive a fall from a tree or a cliff, that could wind the evolutionary clock back a good deal further. (Arthropods are animals with external skeletons and jointed legs, including spiders, insects and crustaceans like the horseshoe crab.)

Gliding under control is neither rare nor constrained to ants, Dudley says. “There are wingless aphids and flat spiders that live under the bark that can glide at a 45° angle. Controlled aerial descent has hundreds or thousands of independent origins in terrestrial arthropods.”

As old as the hills?

Over all, Dudley says, directed descent probably originated about 280 million years. If jumping like a flea or grasshopper is also deemed a form of flight, the origin could date back more than 400 million years.

The gliding hypothesis would not only help explain the origin of a common and cool behavior, but could take wind out of the sails for a favorite anti-evolutionary argument. Creationists, Dudley notes, have long demanded to know how wings evolved by asking, “What good is half a wing?” But according to the gliding hypothesis, wings unable to hold an animal airborne could still have evolved to help control a descending behavior that had long been in existence.

Flight of the control freaks?

Controlled gliding, Dudley says, “preceded the origin of wings, and so the evolution of flight is more about control than about the formation of wings.”

The new analysis “addresses qualms about the [supposed] lack of intermediate forms in the fossil record,” Dudley says. “Here is a viable intermediate form. There are lots of behavioral and ecological contexts where stubby, partial airfoils are useful.”

– David J. Tenenbaum

Among all animals, amphibians are in the worst shape; fully 30 percent are classified as threatened or endangered. Amphibians – including frogs, toads and salamanders — are under attack by a deadly fungus. They are losing habitat to farms and cities, and collected as food or pets. Amphibians are suffering from chemical pollution and the warming climate.

The present is harsh enough, but the future seems worse.

This week, Nature publishes the first global attempt to forecast the impact of three big threats to amphibians by 2080 – a year chosen to be one century after the study’s baseline data.

By comparing areas with plenty of amphibian species with projections of climate change, land use change and the chytridiomycosis fungus, the researchers forecast a grim future for these cold-blooded, four-legged vertebrates. “The bad news is that more than two-thirds of all high-richness regions will probably be affected, to a high intensity, by one of these three threats,” said lead author Christian Hof, who did the work as a Ph.D. student and post-doctoral fellow at the University of Copenhagen.

The geographic study of data on 5,527 amphibian species found little overlap between the cool, moist areas afflicted by fungal serial killer chytridiomycosis, and the places likely to suffer the worst effects of changes in climate and land use.

And the losers win!

In forecasting the future of amphibians, the study coined two technical terms: “losers” — species that are expected to suffer due to disease or changes in climate or land use, and the less numerous “winners,” which are expected to prosper by 2080.

The projection hinged on whether an expected change would make a habitat more or less suitable to the species, says Hof, who’s now at the Biodiversity and Climate Research Center in Frankfurt, Germany. “We ran a number of climate-change models and based on them, calculated a change in climate suitability for each region across the globe.”

Based on these changes in suitability due to climate, land use and disease, Hof adds, “We calculated the number of species that would probably decline due to a decline in habitat suitability. We classify the species as a loser in a particular region, but that does not mean it will decline across its whole range.”

Overall, the researchers found an increasingly dire future for amphibians. For example, 54 percent of frogs are likely to be “climate losers” in the average grid cell of their model. And heavy impacts are projected for about two-thirds of the regions with the highest species richness in frogs and salamanders.

In fact, the future could be even worse, since the study ignored a number of potentially damaging factors, including chemical pollution from cities, factories and agriculture.

Photo: Robert Fletcher, Ohlone Preserve Conservation Bank

Tougher times might await this prowling California tiger salamander, an endangered California native.

Going down!

It’s frustrating but understandable that the study could not predict rates of decline among amphibians. “For many species, we are not sure about the actual distribution, many have tiny ranges and we don’t know where they occur, so we can’t relate historic changes to, say, climate change. We were very careful not to predict extinctions, based on these uncertainties.”

Data are scarce in the study of amphibians, agrees Anna Pidgeon, an assistant professor of forest and wildlife ecology at University of Wisconsin-Madison. “It’s frustrating, amphibians are out at night, often in remote areas, they are small and many are cryptic, so it’s a huge challenge” to understand their populations and ecologies. “We work with the best data we have all the time … and try to make inferences from what we know about close relatives.”

Pidgeon, an expert on habitat needs of vertebrates, says predicting 70 years into the future is always dicey, but that the study’s analysis of multiple threats and global scope are major accomplishments. “They did a lot of things to make sure they were using consensus data, and that makes it a pretty solid approach.”

Although the study looked at overlapping threats, it did not actually look at interactions between those threats, Hof says. “What needs to be done, and we could not do that with our model, is to look at, for example, how climate change would affect susceptibility to the fungus. How would habitat fragmentation affect susceptibility to climate change?”

Although the study does not suggest practical changes that could sustain amphibians in the short run, “The general conclusion is that it’s very important, when thinking about the future for amphibians, to consider different threats together,” says Hof. “Just looking at one threat will not give us the whole picture.”

– David J. Tenenbaum

She asks if she’s overweight, and you wait half-a-second before responding, “Of course not, dear! I’ve just been noticing how slim you look these days.”

Any well-schooled husband knows the pitfalls of faltering in this “marital duet.”

Photo courtesy Eric Fortune and Melissa Coleman.
Video courtesy Science/AAAS

This image is an adult male plain-tailed wren.
Watch the video explaining how the bird-songs
study worked — with ultra-cool bird songs.

And now, we find a similar phenomenon among a singing duet by plain-tailed wrens, natives of the cloud forest in Ecuador.

Pairs of these wrens engage in a high-speed duet that relies on perfect timing: She utters a call, and if he chimes in on cue, she sings her part, and the duet continues.

If he’s late or silent, she is slow to resume the song.

This is cooperative behavior, but close examination also reveals a new mental phenomenon, says Eric Fortune, an associate professor of psychological and brain sciences at Johns Hopkins University. Fortune, first author of a study of the wrens that appears today, says his research “indicates that the full mental representation of the song exists in both birds, even though each one contributes only half of the song.”

The study looked at the interaction between the hearing and motor circuits in the brain via a concept called “mirror neurons.” Discovered in 1983 by Dan Margoliash of the University of Chicago, mirror neurons were “a key discovery that has profoundly shaped our thinking,” Fortune says. “He showed that an area of the brain used to control song responded only when the bird heard a playback of its own song, but not of any other bird’s song.”

Zina Deretsky,
National Science Foundation

Takes two to tango: The song of the plain-tailed
wren is a his-and-hers production.

These nerve cells, since seen in people, other primates and birds, are now called mirror neurons. In simple terms, mirror neurons allow a bird that hears its own song to “imagine” singing that song.

Brainiest birds?

In the new study, however, the mirror response occurs when an individual in a pair hears both birds singing — a sound that each bird cannot produce by itself.

In 2006, scientists identified the plain-tailed wren’s song as a two-part composition that required cues from both partners. “When we heard about these wrens, where one-half of the song is produced by the female, and the other half by the male, we thought, ‘This is amazing. Here’s a song this bird has learned completely in the sensory part of the brain, but it has only half of the motor program.’”

How could this work?

To unravel the sensory-motor linkage, Fortune, with Gregory Ball of Johns Hopkins and Melissa Coleman of Claremont McKenna College, recorded pairs of plain-tailed wrens, manipulated the songs in various ways, and then played them back.

They found that the birds not only sang in pairs, but sometimes also sang solo, making the same calls it would otherwise contribute to the duet, but with altered timing. They found that when a male flubbed his lines, the female might continue to sing, but with a measurable delay. “She’s waiting for him, then gives up and sings anyway,” Fortune says.

The birds were basing their behavior on what they heard — not very surprising. But the fascinating part emerged from the fact that they were engaged in a truly cooperative, back-and-forth behavior that was deeply embedded in the mirror neurons.

Both images courtesy Eric Fortune and Melissa Coleman

Like many field worker, Fortune had to make do with local material, as
shown in this laboratory. Rollover for a look at their solar and
hydro-powered neurophysiological rig, featuring a home-made version
of a $7,000 vibration damper.

Such cooperation, also evinced by dancers and musical ensembles, requires each party to know its own part, but the brain studies showed that they knew much more than that, says Fortune, who is also a visiting professor at Catholic University in Quito, Ecuador. “Both birds had very similar patterns of activity. The neurons responded most strongly to the combined song, not to their own part. The brain knows that they were trying to do this together.”

Got my eye (and ear) on you, mister!

Although Fortune says the songs are probably used to defend territory, he suspects she is also checking him out, gauging his evolutionary fitness, much as female birds rate a fellow’s feathers. “The female is testing the male’s ability to cooperate,” Fortune says. “She produces a long song, and the male has to work hard to insert his syllables at exactly the right time.”

Louis Vest

People also learn cooperatively. Do these
tango dancers hold a representation of the
complete dance in their heads, or is this just
another example of sexual selection at work?

These wrens, he says, “are wired to cooperate. There is a set of rules and the male’s job is to respond rapidly and accurately to the female’s challenge.”

It’s not just feathery guys that fail to respond on cue, and the evolutionary significance could extend far beyond birds. “This happens a lot in people,” Fortune speculates. “Why do women get annoyed when you forget their birthday? They are challenging your neural circuitry. It’s not like flexing your muscles; they are probing your brain. That’s a stronger cue for sexual selection.”

Bringing it back to birds, Fortune says, “It’s most surprising that these animals have a memory of their cooperative behavior in the brain, which includes the performance of another animal; this had not been shown before on a neurological basis. You can take their own half of the song, and play it back, and the motor neurons fire,” but the response is much more powerful when the bird hears the full, two-part song.

— David J. Tenenbaum

Humans and cats go way back. The relationship sprouted around 2000 BC in Egypt, where humans first domesticated felines. Today, more than 90 million cats in the United States alone enjoy the companionship of humans, while another estimated 90 million are stray or feral.

As in most relationships, there are still secrets between humans and their feline friends. But a recent study published in the Journal of Wildlife Management shed light on one secret that may have been nagging cat owners: what do outdoor cats, otherwise known as “free-roaming,” do all day?

Since there are several cat enthusiasts at The Why Files, we, too, wondered about the answer to that question. And the answer belies a few thorny predicaments peculiar to the cat-human relationship.

A day in the life of a free-roaming cat

Decked with radio collars that tracked their every move, 42 free-roaming cats (18 of them pets, 24 of them owner-less) were the stars of the two-year University of Illinois study. The researchers’ goals were to compare what owned versus un-owned cats did all day, where and how far they wandered, and how likely they were to survive in the often risky outdoors.

Certainly, to no cat owner’s surprise, the felines spent much of their time lounging or sleeping, just like their strictly-indoor counterparts. However, the amount of time pet cats versus owner-less cats spent snoozing differed significantly. Pet cats lazed about for 80 percent of their days, while un-owned cats loafed for “only” 62 percent of the time.

“That alone is very interesting. It could be associated with their requirements. It’s possible that the cats without owners have to spend more time looking for resources to take care of themselves,” speculated Nohra Mateus-Pinilla, study co-author and wildlife veterinary epidemiologist at the Illinois Natural History Survey.

Another important finding, according to Mateus-Pinilla, were the differences in the cats’ ranges. While, not surprisingly, un-owned cats roamed further afield than owned cats, Mateus-Pinilla and her co-authors were surprised by how far the stray cats strayed and by the diversity of habitats they skulked in, as compared to pet cats. While most of the pet cats stuck close to home, the most itinerant stray cat wandered around a 547-hectare (1,351-acre) area.

From original map by Jeff Horn

Despite range differences, un-owned and owned cats’ territories can overlap. The red outline shows the largest range tracked for an un-owned cat in the study, and the yellow dot indicates one pet cat’s range.

“Because of the large home range sizes in the evidence of both cats without ownership and cats that are owned, their home ranges are overlapping. And because of the mortality evidence, these animals could be facing a certain amount of risks that we are unable to measure,” said Mateus-Pinilla.

Indeed, the risks of being a free-range cat are much higher than those of indoor cats, and if the cat has no owner, its fate is almost always bleak. In their study, six stray cats died, while only one owned cat died.

Mateus-Pinilla said their study raises many new questions. To The Why Files, however, it seems that living in the company of humans has its advantages for cats. But keeping this relationship indoors may have advantages for wildlife and people too—-implications that drive the otherwise curious research on free-roaming cats.

Too many kitties on the range

While the indoor-outdoor debate lives on in the cat owner community, and regardless of whether or not cats enjoy the out-of-doors, their secret lives outside entail some dirty secrets that are alarming scientists and laypeople alike.

The sheer number of free-range cats, owned or not, has become a conservation and health concern, some scientists say. Like any species, too many can spell trouble.

Cats, by nature, are superb predators. A cat stalking a bird or squirrel is simply doing what cats do. However, their prowess as hunters, combined with their overpopulation, has wildlife biologists and enthusiasts biting their nails over the potential endangerment or extinction of some prey species.

“There are a growing number of landscapes in which free-ranging cats are not only the most abundant mid-sized mammalian predator, but they can outnumber all of the native mammalian mid-sized predators combined. So they really do become the dominant mid-sized predator in many landscapes,” said Stanley Temple, an emeritus professor of forest and wildlife ecology at the University of Wisconsin-Madison, who was among the first to study the ecological impacts of free-roaming cats.

Because of their impacts on both native predators and prey, conservation scientists consider free-roaming cats invasive species. While not the greatest threat to wildlife, they add to the increasingly complex web of existing threats.

Species most at risk of death-by-kitty are birds that spend a lot of time on the ground, small mammals and reptiles, according to Temple. In fact, cats are second to habitat destruction as the cause of bird extinction. Thirty-three bird species have met their fate to the paws of cats since the 1600s.

The world’s ever-shrinking “islands” of wildlife habitat are hotspots of conservation concern over free-roaming cat populations, since the native species in these areas are the hardest hit by invading cats. For example, birds that live in America’s dwindling grasslands or on the increasingly crowded seashore are finding themselves in a precarious situation.

Open and fragmented landscapes, which also include forest outskirts and farmland, are the territories of choice for cats. And, except in subtropical locales, they tend to stick close to humans. Even if un-owned, most cats are still dependent on people for either food or shelter, or both.

“They are remarkably resourceful at taking advantages of the opportunities that we present,” said Temple, who clarified that free-roaming cats are only truly “feral” if they are completely independent of humans.

Their dependency on humans highlights another dilemma: free-range cats can easily spread diseases and parasites that can jump from cat to cat, cat to wildlife, and even cat to human. The list of contagions includes feline leukemia, feline immunodeficiency virus, worms, rabies and toxoplasmosis, a parasite-caused disease that can damage the developing brains of unborn human babies, if their mothers are infected.

Free-roaming cats’ close proximity to both humans and other animals thus creates a potentially strong reservoir for these diseases. While vaccinating both owned and un-owned cats can help reduce the spread of disease, vaccines are not 100 percent effective and the logistics of vaccinating every single cat may be impossible, especially since many vaccinations are annual.

Photo: Rodrigo Basaure

These street cats certainly benefit from a human handout, but do humans benefit from the cats’ potential disease threat?

It’s complicated

Indeed, solutions to these predicaments aren’t easy. While the science may seem to imply that rounding up every cat on the range may be the best solution, the ubiquity of free-roaming cats and the emotions wrapped up in some people’s relationship with felines complicate the matter.

Studies suggest that many free-range cats are people’s beloved pets that are allowed outside, said Temple. But, while keeping every pet cat indoors would significantly and immediately cut the number of free-range cats, not every cat owner agrees that indoor life is best for kitty.

To further complicate things, one of the often promoted “humane” methods of attempting to reduce un-owned cat populations — trap, treat, neuter, release — repeatedly fails. Not only are there always the cats that get away, but releasing the cats back into the “wild” still does not eliminate the risks to wildlife.

Temple believes that for a cat-control method to work, three criteria must be met: the strategy must actually control cat numbers over large areas, it can’t harm any other part of the ecosystem, and it is socially acceptable. The last criteria can be the trickiest to meet and often creates tension between humans.

Photo: Flickr

Is this outdoor kitty taunting his indoor pal? But who has the better life?

“The divide over how to deal with cat overpopulation, in one way, can be simplified as the group of people who are really concerned about ecological impacts of cats versus those that are really concerned about the welfare of individual animals,” said Temple, based on his years of experience conducting public outreach on the issue. He clarified that he likes cats and is actually the owner of a 21-year-old feline.

Temple believes solutions that meet both factions on common ground do exist. Keeping pet cats inside and trapping, treating, neutering and confining un-owned, free-roaming cats are two strategies that meet his criteria. Though, for some people, it will take some convincing.

Mateus-Pinilla was careful to emphasize that their study did not seek to evaluate management options. They were focused on adding to the science and remaining neutral in the debate about solutions to the issue of free-roaming cats.

– Jenny Seifert

For controlling agricultural insects, bats are worth at least $3 billion a year to U.S. agriculture, according to a 2011 study from Boston University. “People often ask why we should care about bats,” said study co-author Paul Cryan, a research scientist with the U.S. Geological Survey in Fort Collins, Colo. “This analysis suggests that bats are saving us big bucks by gobbling up insects that eat or damage our crops. It is obviously beneficial that insectivorous bats are patrolling the skies at night above our fields and forests—these bats deserve help.”

As conservation officials scramble to respond to white nose, they are enacting quarantines to prevent people – cavers, bat-lovers and scientists alike – from transporting the fungus between caves. Last year, for example, the National Wildlife Refuge System halted public access to all caves and mines on its refuges, and set protocols to prevent scientists from spreading the infection.

In May, 2011, the Fish and Wildlife Service rolled out a national plan for confronting and controlling white nose syndrome.

But bats can do plenty of transportation on their own. Even non-migratory bats may fly 200 miles between their hibernation site and their summer range, says David Blehert, a microbiologist at the U.S. Geological Survey National Wildlife Health Center in Madison, Wis., and a leader of white nose studies. “They can move large distances, across state lines, so there is potential for significant disease spread based on bat-to-bat interactions.”

What is the white nose syndrome situation now? Why is it so deadly? What bright ideas are afoot to preserve insect-eating bats, and what is the likely end game?

Why deadly?

In the short time since white nose syndrome appeared in 2006, scientists have pinpointed a fungus called G. destructans as the killer. But how does G. destructans do its work? One clue comes from the fact that it only kills during hibernation, when bats live in mines and caves at a rather chilly 7°C. “The fungus only grows in the cold, and when insectivorous bats hibernate in a temperate region, they drop their core body temperature to the ambient level,” says Blehert.

(The fungus is not likely to attack fruit-eating bats, says Blehert, because they do not have long periods of “torpor,” the slow-metabolism hibernation state that is conducive to the white-nose fungus.)

A low body temperature allows the bats to survive winter without eating, but it could also curtail the immune system, Blehert says. “Studies of bat immunology are in their infancy, but based on what is known about the physiology of other hibernating mammals, especially the 13-lined ground squirrel it’s likely that the immune system becomes suppressed, and that leaves them particularly vulnerable” to the fungus.

How does the fungus kill? It apparently does not enter systemic circulation, as internal organs are not damaged. All mammals awaken from hibernation occasionally, but Craig Willis of the University of Manitoba has speculated that infected bats have more waking hours, causing them to run out of energy during a period when they neither eat nor drink.

Blehert and his colleagues favor a second explanation: dehydration. Despite the “white nose” name, Blehert says, the most significant infection occurs on the wings. “The wings of a bat have eight times as much skin as the trunk; it’s a massive, very delicate and exposed membrane” with a single layer of epidermis surrounding a thin layer of connective tissue and some muscles and glands. “The fungus selectively invades the wing skin, and destroys everything in its path,” Blehert says.

Beyond their role in flight, bat wings are also needed to regulate temperature, fluids and electrolytes. “The wings may be the Achilles heel that exposes them to such significant infection,” Blehert says.

Indeed, an emerging disease that is devastating amphibians, the chytrid fungus, also affects the skin, and is thought to kill by causing an electrolyte imbalance. “The amphibian’s skin is very important for the balance of water and electrolytes, which has been the basis for our hypothesis about why white nose syndrome is so deadly. There was a paper¹ in 2009 that demonstrated that a superficial chytrid infection causes an ion imbalance in frogs, causing a disruption of the potassium gradient that causes the heart to stop. A superficial fungal infection causes a cardiac arrest! This is a very different concept than getting athlete’s foot and having an itchy foot.”

Stopping the wave of death

As dead bats pile up in caves, what can be done to stop the spread of G. destructans? The first step, trying to slow dispersal, is already under way in affected states, with restrictions on cave entry, and new protocols for disinfecting equipment and people who have a legitimate reason to visit hibernation spots.

The fungus does respond to common anti-fungal agents, according to a 2011 study, which found, unexpectedly, that the meds worked at the low cave temperatures that the fungus prefers. “The challenge is, how could you use pharmaceuticals to manage a disease in free-ranging wildlife?” says Blehert. “They don’t go to the doctor, and they inhabit environments that are likely contaminated with fungus. Say you could treat bats and cure them of the infection. If you can’t remediate their hibernation sites, they will become reinfected when they re-enter the cave.”

The authors of the anti-fungal study did raise the possibility of using meds to decontaminate caves, but this process is not being done, Blehert says. “Going into a cave with a general fungicide would be like dropping a nuclear bomb on a city. Caves are full of bacteria, fungi, invertebrates and vertebrates that may only exist in that unique ecosystem, and getting rid of such an important group of organisms [fungi] could risk significant unintended consequences.”

Willis has proposed using little heaters, since bats seem to fare better in warmer regions of caves, perhaps because that sustains immune function. Small heaters are being tested as bat refuges in some New York State caves, says Lisa Warnecke, a post-doctoral fellow at Manitoba.

Lessons from Europe

G. destructans is an “emerging exotic disease,” and to investigate such diseases, scientists always want to know how the pathogen interacts with hosts in its land of origin, which seems to be Europe:

In 2009, the fungus was found in a greater mouse-eared bat in France²;

ENLARGE

Photo: Gabrielle Graeter, NCWRC

Is this bat unhappy about the tufts of fungus on its muzzle — or the researcher’s big hands?

During the winter of 2009-2010, infected bats were found in 76 of 98 sites in the Czech Republic; and

A 2010 study³ in Europe found a white nose pathogen in 21 of 23 suspected bats that was “100% identical” to the U.S. pathogen.

Although the fungus been found in at least five bat species in Europe, die-offs have not been seen there, suggesting that something is different about how the pathogen, host and environment interact. Pathogens and hosts co-evolve through time in a complex dance:

The pathogen may become milder, improving its own survival (and that of its host);

hosts may evolve immune resistance; and

hosts can change their behavior to reduce exposure to the disease.

In the lab in Manitoba, Willis and Warnecke are studying how long little brown bats are awake during hibernation, whether the fungus is a necessary and sufficient cause of death, and if the North American or European strains of fungus have different effects on the bats. “If both isolates show the same severity for North American bats, that may mean that bats in Europe have co-evolved with the fungus and are resistant to it,” says Warnecke. “On the other hand, if the European isolate does not cause trouble for North American bats, then the fungus in North America is a mutant that has gotten really aggressive.”

Other factors could explain the lack of disease in Europe, says Blehert. “European bats are larger, which may provide them with more of a buffer against a physical insult like a fungal infection.” The little brown bat, the preeminent victim of white nose, weighs about 6 grams – about the weight of two pennies, Blehert says.

European bats also tend to hibernate in small groups. “They don’t have those 100,000-plus hibernacula like we see in the United States. With fewer animals, the disease transmission dynamic is likely to be reduced, with less amplification of the fungus, and lower rates of bat-to-bat transmission.”

In the long run, Blehert says, American bats may evolve some resistance. “In general, the population decline in caves and mines comes to about 78 percent, but the bats have not disappeared. We would expect something that gets into population to cause high mortality and a steep drop-off in population. Then, with fewer animals around, disease transmission could moderate.”

Although the regional extinction of the brown bat has been predicted to occur 16 years from now, “our bats may ultimately develop population dynamics more like Europe, with fewer animals and moderated disease transmission and progression,” Blehert says.

Evolution, in other words, could select for animals that, for behavioral or immune reasons, are less susceptible to white-nose.

But letting the situation play out without trying to help the bats, Blehert says, amounts to a high-stakes gamble with one of the wonders of the night sky.

Admit it: You love your dog, your cat, even your white rat.

And so you’re planning to lavish a platter of filet mignon on your doggy-love… a plank of sushi-grade tuna on kitty numero-uno, and some aged cheese on your rodent.

But do our dogs, cats and rats love us back?

Sure, parrots are endlessly uttering “I love you” on You Tube, and some bereaved dogs seem to grieve for their dead owners.

And yes, some animals “love” to spend time together.

But that doesn’t answer our nagging question: Can animals really love?

Or are we projecting our own feelings of affiliation, closeness, and passion on beasts that don’t have the mental machinery to love?

Almost like being in love?

More than half a century ago, Harry Harlow, a research psychologist at the University of Wisconsin-Madison, performed experiments that forever changed our view of human and animal emotions. At a time when academic psychologists explored learning and behavior by studying rats, when low-grade learning in a “Skinner Box” was considered high-grade science, when hospitals limited contact between mothers and their newborns, Harlow focused on maternal touch and the emotional life of monkeys.

Harlow removed infant macaques from their mothers, then raised them with a mother surrogate made of cloth or wire. In some experiments, both surrogates were present.

Monkeys with the cloth mommas grew up fairly normal, but infants raised with only the wire monkey became fearful and desperate. Their behavior was so bizarre that they seemed psychologically broken by the lack of a loving — or at least a cuddly-if-inanimate — mother.

Infants that had access to both types of bogus mother still relied on the cloth mother for reassurance even if the wire monkey held their bottle.

Harlow interpreted the lifelong devastation of maternal deprivation as proof that infant monkeys need love, and that became early, influential evidence that animals can love, says his biographer¹, Deborah Blum, a professor of journalism at UW-Madison. “Up until that point, people were arguing that these animals were not capable of having emotions. Harlow led the way in demonstrating that these animals loved, had affection, mattered to each other. He used the word ‘love’ very deliberately,” Blum adds, even though his fellow psychologists were highly skeptical, not to say scornful, of that notion.

It didn’t take popular psychology, aided by Harlow’s humorous, down-to-earth approach, long to realize that the then-current “scientific” preference for antiseptic infancy would deprive young people of necessary contact, Blum notes. The instinctive desire to hug an infant, it turned out, gained support from the most rigorous scientific experiments.

My romance

Scientists who say that primates need maternal love are no longer mocked by their peers. But what is love? Charles Snowdon, a UW-Madison professor of psychology who has explored primate behavior for 35 years, offers this definition: “a preference for one other individual that is more or less exclusive and long-lasting, and that transcends other relationships.”

Animal love is evident in behavior when animals are separated from their mates, Snowdon says. “In species that form lifelong attachments, if a mate dies or disappears, often the remaining mate does not form a new pair bond at all.”

Snowdon says the cotton-top tamarin he studied form strong attachments. “If they were separated, they would begin long calls, at a rate much higher than they would give when together. These plaintive calls would last for the entire 30 minutes of separation. When they were reunited, they cuddled and often had sex.”

As if that did not sound human enough, Snowdon next floored us by discussing “romantic love.” Decades ago, psychologists worked overtime to avoid being accused of anthropomorphism — projecting human qualities onto animals. Now it’s kosher to talk about an emotion once restricted to the primates that buy heart-shaped tchotchkes each February.

Snowdon says romantic love supports the bond in a mated pair, and it’s not just about primates. “Albatrosses and geese appear to form lifelong pair bonds, and robins, blue jays and cardinals might form relationships that last for at least one breeding season; these are strong attachments.”

Snowdon adds that experiments with titi monkeys belie the notion that the sole goal of animal attachment is to nurture the next generation. “If you separate the mother, father and infant from each other, and give them a choice, mothers and fathers choose to be with each other and ignore the baby. It is clear that pairs want to be with each other, to the exclusion of the baby.”

Like someone in love

While Harlow relied on observing behavior, today scientists study the brain chemicals that mold the Valentine’s heart. One key subject is the hormone oxytocin, which plays a critical role in social bonding and love, both animal and human.

Oxytocin, originally identified for its role in helping mothers bond with newborns, also rises in men and women after sex and other close, emotional encounters. In the big picture, oxytocin enables attachment in humans and other animals, Snowdon says. “You don’t find oxytocin elevated in animals unless they form an adult attachment with one other individual.”

The brain responds to dopamine, a feel-good chemical that is released during many pleasurable activities, including drug-taking. Dopamine also plays a role in animal love – and “marital” fidelity. Mated prairie voles have a higher level of a specific dopamine receptor in a brain region called the nucleus accumbens, says Karen Bales, an associate professor of psychology at the University of California at Davis. “When these are turned on, that prevents them from forming a second pair bond.”

When owners interact with their dogs, both sides have surges in oxytocin, says Bales, who studies primates at the California National Primate Research Center. “That puts a check in the ‘dogs can love’ box.”

Love fur sale

Because dogs are the most glaring example of an animal that seems to love people, we phoned Patricia McConnell, an author³, and animal behaviorist at UW-Madison. She gave us two key reasons why dogs can love: “Their physiology for creating social attachment is so similar to ours, and they behave in ways that, if any human did it, we’d label it love, attachment.”

Like many other mammals, dogs respond to oxytocin: “It’s a huge part of social attachment, and physiologically it’s almost an exact replica of oxytocin in humans,” McConnell says.

Dogs appear to grieve, McConnell adds. “They get distressed when someone they are attached to is gone. There are lots of credible examples of dogs risking their lives to save a human. We are so different from dogs in so many ways, but in some ways, we are more similar to them than to other animals. What other species is obsessed with the fate of a ball?”

If dogs love us, what about each other? “Absolutely, yes,” says McConnell. “I have seen dogs behave as if they instantly fell in love: they are animated, their eyes were shining, they were extra playful. But I’ve also seen dogs that clearly took an instant dislike to each other.”

Dogs, like people, are picky, so it’s not always possible to replace a deceased member of a tight pair, McConnell says. “When people get another dog, they’re often surprised that the resident dog is not thrilled. We see the exact same thing in people: Personalities can clash or meld. When someone you know dies, it will not help if a stranger walks in off the street.”

You don’t know what love is

Still, animals can’t say what they are feeling, and so we must rely on measurements and observations. Interpreting animal behavior can be difficult, says Marga Vicedo, a historian of science at the University of Toronto who has written about Harlow’s experiments.⁴

Vicedo recalls members of an animal-behavior seminar who would “discuss, week after week, how you would interpret it when they look left — or right? You are seeing a behavior, and from the behavior, you have to hypothesize about the emotions, but there is not a perfect correlation between animal and human emotions.”

Interpreting the emotional basis of behavior is difficult enough with people, Vicedo observes. “We may laugh at a meeting, but inside we are depressed. You can only observe behavior, and have to figure out its relationship to emotion and feeling.”

Stephen Marc Breedlove, who studies hormones and behavior at Michigan State University, reiterated that problem. “Whether you think your dog loves you or your boyfriend loves you, there is the same problem: you see the behavior and from that, you infer these feelings. With a partner, you can ask, but since people do lie, that is not completely reliable.”

My one and only love?

Our improved understanding of what’s going on inside the brain provides more ways to analyze animal emotion, Breedlove says. “In certain species, there is neural circuitry that helps monogamous pairs stay attached to one another. We know the same systems can be present in humans — and although we don’t know they serve the exact same function, there is some danger in insisting we are absolutely unique in every way. Natural selection produces a continuum of traits, we can’t have something arise from nothing.”

Indeed, evolution is a great re-user of its own inventions, as Breedlove stresses. “What is the evidence that makes you think love arose absolutely de novo [without precedent] in our species? And then, when did it arise, in Mesopotamia?”

The notion that animals can love is part of a scientific sea change. Once upon a time — even after Harlow — identifying emotions in animals was considered anthropomorphism, a fatal fallacy that could ruin a career in psychology or animal behavior.

Now, we have seen a “change in the zeitgeist [the spirit of the time],” says Breedlove. “People are open to the possibility that animals have emotions, and I think that is a step forward, a sign of maturity of the field. Anthropomorphism is definitely a risky business, but people are less worried that they will be written off as cranks just because they say something that could be interpreted as anthropomorphism.”

As we’ve seen, many scientists are even willing to discuss parallels in animal and human love. Heresy!

Almost like being in love

In burying the old “animals are just beasts that cannot have feelings” mentality, nobody has been more influential than primatologist Frans de Waal of Emory University. When we asked whether animals can love, he responded, “Mammals are almost made for attachment, because of their maternal care obligations, the female is attached to her offspring and vice versa. There is a whole brain circuitry attached to that.”

Still, the subjective aspect is hard to know, de Waal admits. Even though studies find attachment, affiliation — and arguably love — in rodents, dogs and primates, “what they experience is not something we can know, but given that they show all the signs of attachment, they spend time together, are distressed if they are separated, and show what looks like happy behavior when they are reunited,” it’s unclear why we should deny the obvious explanation: these animals have emotions.

“If a chimp’s offspring dies,” de Waal says, “it usually keeps carrying it around until it falls apart, so even though the offspring is dead, the attachment stays intact; these are all signs of strong attachments.”

Comes love

We asked de Waal if we could summarize his view as, ‘It looks like love, but we’ll never know?’ but he said we had it backwards. “My assumption is the other way around, that if animals that are closely related to us, as monkeys and chimps certainly are, and do similar things under similar circumstances, we have to assume the psychology behind it is similar. It would be very inefficient for nature to produce the same behavior in different ways in a monkey and a human, it would have to create a different mechanism, a different psychology and neurology. From the Darwinist standpoint it does not make sense that monkeys would arrive at the same place via a different way.”

de Wall said his view is that “If chimps show strong attachment, we have got to assume the psychology is similar, and that would include the experience. That is not an assumption that is easily verified, but I think it is better than the opposite, that it looks the same, but is probably different.”

With fanfare that even snared some attention outside scientific circles, the 10-year Census of Marine Life came to a conclusion Oct. 1. The headlines and self-congratulation were deserved: our “ocean planet” is predominantly covered with salt water, and the Census had strength in numbers: 2,700 scientists from more than 80 nations spent $650 million exploring life in salt water. Working in 25 groups, the scientists sifted and collated old data and performed new studies on 540 field expeditions.

The Census also crafted the ground-breaking Ocean Biogeographic Information System. This public database contains 30 million records on more than 100,000 marine species, derived from new studies and about 800 existing databases that were harmonized for easy digital access (or so we’re told; we confess we’ve not looked up our favorite lobster in the database).

Kiwa hirsuta, Ifremer, A. Fifis, 2006

South of Easter Island in the Pacific, Census explorers discovered the yeti crab, which became the first member of a new biological family, Kiwida (Kiwa was the mythological Polynesian goddess of shellfish). The yeti crab supposedly resembles the abominable snowman, the “yeti.”

The effort was monumental, but necessary, considering that roughly 71 percent of our planet is covered by ocean. For reasons of remoteness, expense, logistics and physics, ocean science is difficult and expensive, and as a result, we know a lot less about life in the oceans than on land.

And even on land, scientists cannot agree on the total number of multicellular species, let alone count the bacteria and other one-celled critters.

The effort to explore salty sections of the planet that began in 2000 has already boosted the number of known marine species from 230,000 to 250,000. About 5,000 more candidate species await analysis in jars and freezers around the world.

What is the big picture?

Educated guesstimates suggest that the oceans may hold 1 million multicellular species – four times the number that’s been cataloged. In total, since 2000, an average of 1650 new marine species have been named each year — proof that the age of biological discovery continues. That number includes about 150 species of fish.

Courtesy Patricia Miloslavich

Half of fish biodiversity in the Caribbean is located near venerable marine science stations (circled). “Very few samples come from the huge, deep-sea basin in the middle,” says Census scientist Patricia Miloslavich. “If you go to places where you have never been, you will find new species.”

Our view of marine biodiversity suffers from sampling bias – we find more species near scientific stations, and that is one error Census projects are trying to correct, says Patricia Miloslavich of Simon Bolivar University in Venezuela. Miloslavich, a co-senior scientist for the census and head of its Caribbean project, says biodiversity data for the Caribbean, “did not show the location of biodiversity so much as the location of marine scientific institutions. There are little hot spots around … the places where most research been carried out in the last 50 to 80 years.”

Because South America extends so far north and south, and fronts two major oceans, it posed a good test for the notion that biodiversity would peak in the tropics and taper off toward the poles. Miloslavich says Census data from South America refuted that conventional wisdom.

Near South America, at 40° to 50° south latitude, biodiversity is much higher in the Pacific than the Atlantic, probably due to the many biological niches in Chile’s convoluted coastline. Scientists traditionally expect to find more biodiversity in the tropics.

In the tropics, the expected high biodiversity did appear in the Pacific and the Atlantic, Miloslavich says. But the Pacific also showed a biodiversity hotspot between 40° to 50° south latitude. “The Chilean fjords are a very irregular coast, with a lot of biodiversity,” Miloslavich says, “but at the same latitude on the Atlantic side, off Argentina, biodiversity was low.”

No way can we summarize this huge effort to catalog and measure ocean life. Instead, we’ll encourage you to browse for yourself while we focus on new data about:

Canada’s coldest realm

The Census of Marine Life studied Canada’s Atlantic, Pacific and Arctic coasts, which by themselves account for 16 percent of the globe’s coasts, says Philippe Archambault, first author of the report on Canada’s “three oceans”.

The Census attempted to negate sampling bias, which had suggested that the Atlantic was more diverse than the enormous Arctic coast, which stretches more than 160,000 kilometers.

Colossendeis colossea, Mylène Bourque, Benthic Ecology Laboratory, Institut des sciences de la mer, Rimouski, Quebec.

This large sea spider, from the Canadian Arctic, feeds on corals and other organisms by sucking their contents through his enormous mouth, or proboscis, located at lower right. Although the sea spider has a small body, its vital organs, including gonads, are housed in its elegant legs.

On the Arctic coast, biodiversity counts covering just 53 square meters (“the size of three Canadian kitchens!” Archambault says) revealed 1,200 species (mainly animals longer than 1 millimeter). In comparison, studies of 170 square meters of the shorter Atlantic coast showed 1,300 species. We offered the conventional wisdom, that the Arctic is biologically boring. “This was not the case when we put out a similar sampling effort,” Archambault says.

The planetary warming that is melting the Arctic ice is already affecting sea life, Archambault adds. In areas that were normally covered with ice for most of the year, the summer melt allows a brief pulse of sunlight that energizes plants, starting a simple food chain in which animals graze the plants and drop to the sea floor, to be eaten by predators. But when the water remains ice-free for more time, Archambault says, small crustaceans called copepods in the water eat the grazers before they can reach the sea floor. “So you now have copepod feces going to the sea floor, and you don’t have the same animals living down below.”

Photo: Casey Debenham, University of Alaska Fairbanks

These subarctic sunflowers live in the shallow waters of Prince William Sound, Alaska; part of an Arctic that now seems unexpectedly rich in biodiversity.

The studies organized by the Census are documenting today’s conditions in the Arctic, so we can understand what happens as the climate changes. “The Arctic is almost the last pristine area on the planet,” Archambault says. “When the ice melts, there will be more shipping, more potential for oil spills, and yet we don’t have baseline information” to help track the anticipated changes. (This video shows biological exploration in the Arctic.)

The Canadian studies highlighted how biology is hobbled by a shortage of taxonomists — experts who can distinguish one species from another. “We are losing taxonomic expertise in Canada, and everywhere,” says Archambault. “We have much more technology for counting species, but this can only help us know how many species are there, it won’t tell us what they are doing.” He notes that the Census of Marine Life had to send 25 samples of polychaete worms, a common sea-bed resident, to Mexico for analysis, and one turned out to be an unknown species. “We cannot do this identification in Canada anymore,” says Archambault. “Taxonomy is not sexy enough!”

A lot of biology is at stake in the frozen realm, Archambault says, yet we don’t even know what’s living there. “Each time we send in equipment, in the Arctic, in the Pacific or the Atlantic, there is a big chance of finding something new.”

Tracking fish

Migrations always fascinate biologists, whether it’s the monarch butterfly winging thousands of miles between central Mexico and the American Midwest, or the Arctic tern, flying a round-trip of about 9,000 miles from the South Atlantic to Norway.

Whales migrate, turtles migrate, and so do fish like the salmon. Because tracking migrations, especially for smaller critters, is difficult, one Census project has laid strings of underwater microphones across rivers, straits and the continental shelf along British Columbia.

The strings can be used to track fish or other animals that carry tiny noisemakers.

On the continental shelf, receivers spaced 800 meters apart can detect 90 percent of the fish swimming past, says Jim Bolger, executive director of POST, the Pacific Ocean Shelf Tracking project. Because the network can identify individual animals, remote-control migration tracking becomes possible once the noisemakers are in place.

Scientists who use the network “are not only looking at where they go and how fast they traveling, but are identifying bottlenecks for survival, where fish fail to show up,” says Bolger, who also directs the Vancouver Aquarium. Such information can abet management measures designed to make life easier for many types of marine creatures.

2004 photo, POST

Acoustic units prepare for a swim in the Strait of Georgia, British Columbia, to prove that these arrays of microphones can track animals bearing distinctive noisemakers.

Salmon in the Northwest have been a focus of concern for many years — as their spawning rivers are dammed, fewer are returning to the ocean to mature. Fish tagging can be used to track salmon, if you can find the fish later on, but POST works much quicker, Bolger says. “We don’t have to wait four or five years to see how they survive; we can measure survival almost in real time.”

Bolger says salmon swim complex routes. A POST study of four salmon species in British Columbia found major variations in swimming speed and route.

A second study of young salmon in British Columbia linked survival to the timing of migration: young salmon that hit the ocean when plankton were blooming had 150 percent to 300 percent better survival.

This type of data could help conservation groups and hatcheries trying to restore salmon, but . “There is no one-size-fits-all strategy,” Bolger says. “Even within the same species, on the same river, we have tremendous complexity in how they swim and where they go. Some go north, others to the south. This could be a survival strategy; they don’t send all their progeny in one direction.”

Photo: POST

The new noisemakers are so small they can even be placed inside young salmon, before they start their migration down rivers and into the ocean.

Information from the acoustic array can also be melded with data on genetics and physiology, Bolger says. “We can see whether fish with high levels of stress hormone behave differently than those with low levels. Scientists can examine the blood chemistry and genetics when the tag is implanted,” and then correlate the data with their subsequent movement.

The magic of microbes

Perhaps the biggest single question about ocean life concerns microbes — bacteria, their primitive relatives called Archaea, and other single-celled organisms such as protists and ameba. Species are difficult to define in bacteria and Archaea, which is why scientists use “taxa” instead, but the numbers are daunting: the oceans could contain tens of millions of taxa, and the exploration has just begun.

“Small” does not mean insignificant: the approximately 10²⁹ microbes in the sea weigh one trillion (1,000,000,000,000) tons, and comprise an estimated 90 percent of life in the ocean, by weight. Not only are microbes critical to the food chain, but they also engineer many of the basic chemical reactions that move fundamental elements like carbon and nitrogen through the oceans.

Global Seafloor Biomass

Photo: Chih-Lin Wei and Gilbert T. Rowe

By measuring carbon, scientists estimated biomass, including creatures from bacteria to plants and the biggest animals, at the seafloor. Generally, the tropics seafloor is low in biomass compared to temperate and polar regions.

Scientists long ago gave up trying to distinguish microbes by growing them in culture, and now count them with genetic techniques nick-named “molecular bar-coding.” These methods evaluate similarities and difference in a specific section of the genes, then use the data to build an evolutionary tree. Bar-coding applies to all life, and is widely used to assess evolutionary relationships in higher organisms as well as bacteria.

Ten years ago, scientists using molecular bar-coding concluded that a single liter of ocean water might contain 3,000 types of microbe, says Mitch Sogin, of the Marine Biological Laboratory in Woods Hole, Massachusetts, and a leader of the International Census of Marine Microbes, “But what blew the doors off that estimate was a very deep molecular sampling effort in 2005 … which revealed that the number is at least an order of magnitude higher.”

Today, it’s estimated that a liter of seawater may have 30,000 to 40,000 types of microbes, Sogin says, “so if we take all 1,200 samples [from the microbial wing of the ocean census], we very conservatively estimate that they contain one-half million kinds of microbes.”

There are reasons to suspect that the actual number may be much higher, Sogin says, but even using this definition, “Every time we look at a new sample, we identify new taxa, and yet we have only sampled 1,200 liters, which is 1 in 10 ¹⁸ parts of the total ocean.”

when bacteria make rock

Loihi Seamount, courtesy Katrina Edwards

An iron-processing bacteria (bean-shaped object) forming iron-oxide needles.

Unfortunately, molecular bar-coding does not show what newfound microbes are eating, or how they affect their surroundings. At Loihi Seamount, a submarine volcano near Hawaii, marine census scientists have explored microbial iron-mongers. Katrina Edwards, a professor of marine and environmental biology at the University of Southern California, says, “At Loihi, we could dig our heels in to study a particular class of microbes that we think are pretty ubiquitous at the seafloor.”

These bacteria “play a very large role in iron oxidation and the deposition of enormous quantities of iron oxide,” which eventually becomes rock, Edwards says. “If we can understand how these rocks are formed in the modern world, and can understand the physiology, genome and ecology of the bacteria, we can interpret” old rocks found in other locations.

Microbes: Why so many?

Linda Amaral-Zettler, a microbial ecologist and program manager for the International Census of Marine Microbes, has a question: “Why are there so many different kinds of microbes living in this environment, that at first blush, seems uniform?”

One answer comes from the billions of years of every that have produced so many life patterns and genetics. But another answer, she says, may be “that there are a lot more niches or places to live than we have appreciated. Somehow these organisms are sensing these micro-habitats and are able to survive despite the competition.”

Photo: Enric Sala

Coral reefs serve as the perfect haven for co-habitation between microbes and sharks!

Microbes can be extremely specialized, and scientists have found that the most common microbes living on one species of sponge are not among the most common on another sponge, says Amaral-Zettler, who works at the Marine Biological Laboratory in Massachusetts. “Animals, plants and other multicellular organisms are likely to be havens for microbes, and we have barely sampled them. Essentially any surface that is out in the ocean can be colonized.”

Even trash?

Apparently. “All the signs say that even garbage is something the microbes are taking advantage of; likely they are degrading it and using it for an energy source,” says Amaral-Zettler, who is starting to examine microbes on plastic in the sea in collaboration with the Sea Education Association.

Here’s another question: Why are most of the microbial taxa discovered by the Census so rare? Having a few dominant species and plenty of rare ones is often characteristic “of an environment that is impacted in some way” Amaral-Zettler says, “but it seems to be a repeating pattern in the sea; we see it everywhere we look. We are struggling to understand the ecological consequences of having so many rare microbial species.”

Photo: Karen Gowlett-Holmes

Plant or animal? The leafy seadragon confuses predators by mimicking drifting seaweed.

This business of the “rare biosphere” fascinates Sogin, a specialist in microbial evolution, who suggests that the many rare species:

Should we worry?

If there is an uncountable diversity of microbes in the sea, should we ignore the conventional cavil about biodiversity — that too many species will go extinct? Why worry if the sea has more microbes than we can count?

Not so fast, says Sogin, who warns that we are changing the sea in ways that could harm microbes and boomerang back to harm us.

It’s not just that all multicellular organisms evolved from single-celled creatures, Sogin says. Life can survive happily without people, but life relies on microbes. “During 80 percent of the history of life, microbes transformed the planet into something that was habitable by multicellular organisms. They created an environment we can live in. This process continues, because so many microbes in the ocean carry out processes that are essential to our survival.”

People, after all, are dumping garbage, sewage and fertilizer into the ocean, warming it with greenhouse gases, and as the ocean absorbs our carbon dioxide, it becomes more acidic.

Since we don’t understand how the ocean works, we cannot predict the consequences of a major change in the environment.

However, Sogin says, “We know from lab work in microbiology that tremendous shifts can occur in population structures and lead to an imbalance and then a further change in environmental conditions. What will happen with continued ocean acidification or a dramatic shift in seawater temperature? We are going to have a disruption of the microbial community. Is that good or bad? We don’t know.”