Marine Worms (Flatworms, Segmented Worms, Roundworms)

General Stuff About Worms… Worms are found pretty much everywhere in the ocean. Most worms tend to live near the seafloor. Some of the worms we will be discussing are parasitic. There are a number of different groups, or phylums, each having it’s own distinctive characteristics.

Worms, Worms, Worms!

Phylum- Platyhelminthes (aka: Flatworms)  Have flat bodies.  Found in both fresh and salt water.  Can range in size from microscopic to nearly 20 meters (60 feet!)  Have bilateral symmetry.  Move by contracting muscles and beating of cilia.  Have a very simple nervous system.  Have a very simple digestive system.  Reproduce asexually (regeneration) or sexually (hermaphrodite).

Flatworms

Tapeworms  These worms are parasites.  They live in or on the body of a host organism.  They do not need digestive systems because the absorb nutrients directly from the host into their own bodies.  Some examples are: Blood fluke, Liver Fluke, Trematode.

Tapeworms

Roundworms These are the most common type of worm. There are about 10,000 different species of roundworm! They generally live at the bottoms of oceans, and burrow in sand and mud. They whip their bodies back and forth to move around. Some can swim. They belong to the phylum Nematoda. There are two sexes, but some are still hermaphroditic.

Roundworms

Segmented Worms Typically found in moist soil or sand. Belong to the Phylum “Annelida”. There are more than 10,000 species of segmented worms. They have a well developed digestive, circulatory, and nervous system. They breathe through their skin and have moist bodies. Oxygen and Carbon Dioxide diffuse through the skin.

Segmented Worms