Nematode

The threadworm is commonly found in bottom muck or sand throughout the world. You can tell it from other worms by its S-shaped swimming motion. Most threadworms prefer a quiet life eating tiny plants and animals, both dead and alive. Some nematodes live as parasites on clams, snails or fish. The threadworm gets oxygen right through its skin. This wiry hairlike animal finds quiet water a comforting home.