Nervous Sea Squirts Squirt Out Their Stomachs and Grow New Ones

We may call someone gutless who's acting afraid. But certain coral-reef dwellers take gutless to a whole other level: they shoot their digestive tracts out of their bodies when they feel threatened. This seems to deter nearby fish from taking a bite. Even more amazing, though, is how quickly the gutless animals grow back their organs. Polycarpa mytiligera is a little tube-shaped creature called an ascidian, or sea squirt. It resides in tropical waters of the Indian and Pacific oceans. With its base glued firmly to a coral reef or other surface, it feeds by filtering particles from the passing current. Some sea squirts look like colorful vases arranged together on a reef. But Polycarpa mytiligera lives alone and lets other bits of sea life grow all over its body for camouflage. Scientists first noticed in the 19th century that some sea squirts have no guts. The animals are known ...