Catworms are very rapid predator worms. They hunt young shellfish and other worms, but also eat organic waste and algae. Catworms are very active. They can quickly stick a kind of tongue in and out. They use it to dig themselves rapidly into the bottom. Catworms are very sensitive to severe winters. After such a winter, they can disappear for years. This worm is also sensitive to pollution from oil or drilling muds containing oil.