Polychaetes: Marine Worms

The segmented worms often resemble flowers. Many of them are quite beautiful. They have a pair of large gills which collect food as well as oxygen.

Many lifeforms in the animal world use their breathing apparatus to collect both oxygen as well as food. Bivalves, Horseshoe worms. Gills filter the water and collect food particles. They are a very effective net.

The two main groups of Segmented worms are Wandering worms such as the beach worms and the Sedentary worms that live in tubes.

The sedentary worms are classified according to the type of tube in which they live and how they feed.

The tubes are diagnostic. There are cement tubes, Leathery tubes and sandy mucous tubes.



Terebellid worm cement

Terebellid worms do not have flowery gills for feeding. Instead, they send out long strands seen here which are sticky. Food particles get stuck on these tentacles which are pulled into their central mouth.

Their tube is soft and leathery.

This Serpulid worm has two gills. You can see the cement trapdoor that it uses to cover the opening to its cement tube. These worms have a simple brain around the base of the gills which react with lightning fast reflexes to avoid being eaten by fish.
xmas worm Worm3
The Christmas Tree Worm, Spirobranchus giganticus is a cement worm. It owes it existence to the Parrotfish. Normally, any worm eggs landing on the coral polyps shown are eaten as food. Parrotfish scrape a bare patch on the coral when they feed. Now, any larvae landing on the coral surface can form a cement shell and grow large enough to avoid being killed by the tentacles of the polyps. As the coral grows over the next few years, the worm shell gets larger. However, we cannot see it because it is beneath the surface of the living coral. Chaetopterus is a ringed or segmented worm that lives in a U shaped burrow in the sand. The burrow has made of sand and mucous. Chaetopterus uses its powerful jaws to prey on passing food items.