Phylum Nematoda Roundworms

Phylum Nematoda ~ Round worms tiny, cylindrical worms Inhabit almost every environment, and living thing. Live in extreme environments: frozen arctic tundra, heat of hot springs, heights of mountain tops, depths of the ocean, and highly acidic environments, drought, and famine. Each can survive only in its specific environment.

Ascaris Ascaris- a parasitic intestinal roundworm Basic Body Form has body that tapers at both ends body is a tube within a tube outer tube ~ Consists of the epidermis and cuticle. Cuticle formed by secretions from the epidermis, used for protection and support inner tube= digestive canal- mouth and anus anus- permits the egestion of indigestible materials without interrupting food intake at the mouth

Movement Don’t move smoothly like free living flatworms. They only have longitudinal muscles, so they have a frantic thrashing motion This is different from the free-living flatworms that have special cells that produce slime and then glide along using their cilia and muscle layers beneath the epidermis.

Nutrition Ascaris feeds on the digested food matter in its host’s intestine. Fluid in the pseudocoelom helps transfer nutrients and gases Has two lateral excretory canals and an excretory pore close to the mouth

Body Cavity

Nervous System Ring of nervous tissue around the pharynx and two nerve cords. One runs down the length of the body on the ventral side and the other does the same on the dorsal side.

Reproduction reproduce sexually are not hermaphroditic

Other Roundworms Hookworms, Pinworms, and Trichina worm All parasitic and their lifecycles are similar in many ways to the parasitic flatworm lifecycles. http://www.cdc.gov/parasites/dirofilariasis/ http://www.cdc.gov/parasites/toxocariasis/