Segmented worms are placed in the phylum Annelida, which consists of over 12,000 species of segmented worms grouped into three classes comprising freshwater worms and earthworms, marine worms, and leeches.

Do you know how many species of segmented worms there are? Did you know that segmented worms are highly evolved, with a circulatory system and complex nervous system? There are over 12,000 species of segmented worm – how many segmented worms can you name?

A reader recently wrote to us inquiring about the evolution of worms. He asked several specific questions about the evolutionary history of worms, not all of which we can answer, but we can sketch a picture, even if incompletely, of the evolution of worms.

The limb boring worm tunnels into hard materials such as rocks and shells. While you may never witness a boring worm in action, you may notice their bodies sticking out of mollusk shells and rock cracks after they have tunneled through.

Large bristle worms are usually gray or brownish in color. Some are also salmon pink with white setae around the body. Like most worms, bristle worms are nocturnal, so they are not usually around during the day.