The green Jell-O torpedo you see above is called a salp. Typically the gelatinous little ocean creatures are less ostentatious, but researchers have lent this one some flouresceine dye for a photo-op. They’re interested in the swimming habits and propulsive wakes — here seen as a green plume on the left — of salps because the 1 millimeter long organisms play a critical role in cycling the organic matter of tropical waters. Salps draw in water through a siphon, filter the contents for plankton, and then eject it to make their way. Understanding the trade-offs between feeding and jet propulsion in different salp species will help the researchers understand the organism’s role in some of the ocean’s most crucial and delicate ecosystems.