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Phylum Nematoda

When you are done reading this, take the Roundworms Quiz.

Roundworms are a member of the nemathelminths phylum or group of animals. The hookworm, pinworm and trichinella are part of this group. They are more advanced than flatworms but less advanced than earthworms. They have thin round bodies, with none of the pieces or segments that earthworms have in their bodies.

Roundworms live in salt water, fresh water and the soil. Many of them are harmful to man as they are parasites.

Roundworms Videos


roundworm image

System Type
Roundworms System
Muscular-Skeletal A roundworm has no skeleton.
Digestion A roundworm has a definite digestive system that runs the length of their bodies. It has a mouth, pharynx, intestine and anus. Many are parasites and live off other animals and plants.
Nervous A roundworm has two nerve cords that transmit impulses in the roundworm.
Circulation A roundworm has no heart or formal blood vessels.
Respiration A roundworm has no formal respiratory system.
Reproduction A roundworm reproduces sexually. The female has an ovary, holds eggs in an oviduct and then passes them to the uterus, where they are fertilized. The male has sperm cells are made in the testis and stored in the vas deferens. When it is time to reproduce, the sperm cells pass through the spicule. Over 200,000 eggs can be deposited at once in the soil once they are fertilized.
Excretion A roundworm has an anus at its rear end and a series of excretory tubes that end in an excretory pore.
Symmetry A roundworm has bilateral symmetry.
Appearance A roundworm is thin, round, smooth and can be up to four feet in length.




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