A sea slug in the waters off Bali

© Media Drum World/Alam

Solar-powered sea slug. Adorably evolutionary sea sheep

Perhaps you can understand why this tiny sea slug is sometimes called the ‘sea sheep’ or ‘leaf sheep’? It grazes on algae just as a sheep grazes on grass, and it bears more than a little resemblance to an actual sheep. Sea sheep don’t digest the chloroplasts in the algae they eat—instead, they absorb the energy-producing cells. As a result, the leaf-like fins all over the sea sheep’s back are loaded with working chloroplasts, making the sea sheep one of the only non-plant life forms on Earth with the ability to photosynthesize—that is, produce its own energy using sunlight and water. Who knew an evolutionary advancement could be so cute?