These Sea Slugs Break a Cardinal Rule of Animal Life
Studying sea slugs in the group Sacoglossa can mean being on the receiving end of some very imaginative emails. Sidney K. Pierce, of the University of South Florida, retired a few years ago. “But to this day,” he told me, “I get questions from little kids in their science classes” who have stumbled upon the marvelous mollusks—and want to know if they could help “end world hunger.”
The answer, Pierce assured me, is no. But the proposal isn’t totally outlandish. Several sacoglossan sea slugs can harvest energy from the sun’s rays and, using only the contents of their cells, turn it into chemical packages of food. In other words, they photosynthesize—arguably the plantiest thing that earthly plants and algae do.
Except sea slugs are, of course, not plants or algae. They’re standard-issue animals that have blurred the boundariesphotosynthesizing machinery—in-cell structures called chloroplasts—from the algae they eat, and store the green, light-converting blobs for . Some species can the of these self-replenishing snack packs for months, . One sea slug that Pierce has studied extensively, , can go the rest of its life without eating—moseying, mating, vibing—after just one algae-rich binge in its youth. “We collect them in the field,” he told me, “and we never feed them again.”
