Describe the size of the coloring and the nature of movement of free-living nematodes and roundworms.

Nematodes and roundworms are not only parasites of humans and various animals. Many species are free-living, that is, they do not live in an organismic environment. Nematodes can be very large. Some species are up to nine meters long. They float freely in the water in any direction. They are mostly pale red in color. Roundworms can reach sizes up to half a meter. They can be white. They are also able to move freely in the aquatic environment. Free-living worms are mostly dioecious.