Characteristics

Roundworms are the simplest animals with body cavities.
There are at least 12,000 species known.
Roundworms can be found in lakes, in the earth, and in oceans.
Most Roundworms only grow to be several millimeters long.


A certain type of roundworms, known as hookworms cause diseases. Acting as parasites, some hookworms attach to the bloodvessels, ingesting about one milliliter of blood a day. Anoter type of Hookworm is known to cause disease in pigs. Most hookworms enter the body if it has been walking barefoot on the ground. Treatments have been developed to protect people from hookworms.