Ribbon worm

Ribbon worms, or nemerteans, are a group of very unusual worms related to molluscs and annelids. Most ribbon worms live in the ocean, and some can grow to over 100 feet long but are usually much less than an inch wide. Some species live on land or in freshwater.

Unlike annelids, ribbon worms are not segmented. Instead, ribbon worms look a little like living linguine noodles but are often very beautiful, with bright colours or stripes. They can stretch and contract their soft bodies, and they move by gliding over the bottom using slime and tiny hairs called cilia.

Despite their soft, delicate appearance, ribbon worms are fearsome predators of annelid worms, clams, crabs and even fish. Ribbon worms feed using a proboscis which is kept tucked inside their bodies when not needed. When some species of ribbon worms encounter prey, they push the proboscis out and stab the prey with a barb to inject toxins and digestive juices. Once the animal is immobilized, the ribbon worm swallows its prey whole, and it can eat animals almost as big as they are by stretching its body to fit the animal inside. Other ribbon worms have a branched, spaghetti-like proboscis instead of a barb and secrete toxins onto captured prey. Sometimes, ribbon worms digest their prey outside their bodies and slurp up the soft tissue through their proboscis. Other ribbon worms are scavengers or parasites, and a few are thought to absorb nutrients through their skin.

Because of their voracious appetites, ribbon worms can have huge impacts on commercially important clam and crab fisheries. Ribbon worms protect themselves from predators by secreting toxic slime, but some fish, crabs, seabirds and even other ribbon worms eat them. There are over 1,000 species of nemerteans all over the world.