Nemotodes (roundworms)

Phylum Nematoda (roundworms)

roundworms have bilateral symmetry and their bodies have no more than 2 cell layers. Their body fluids are under high pressure and they have a pseudocoel body cavity and possesses a through gut with an anus. A roundworms body is covered with a complete cuticle. Nematodes apear in almost every habitat except for dry places. 

They reproduce sexually or hermaphroditism may also occur. The basic reproductive structures of a male nematode include: one testis, a seminal vescicle and a vas defrens opening at the cloaca.  Basic female reproductive structures include: one or two ovaries, seminal receptacles, uteri, ovijectore, and a vuvla. The females ovary(ies) that holds the eggs in an oviduct. It then passes them to the uterus. They are fertilized here from the male sperm. The males sperm cells are stored in the vas defrens after being produced by the testis. The sperm passes through the spicule when it is time to reproduce. Over 200,000 eggs can be deposited, once they are fertilized, into the soil.

Some Examples of nematodes are;

Ascaris

 

Wuchereria

Cite:

Pictures:

http://www.ars-grin.gov/ars/SoAtlantic/fp/stpp/burelle/nematode.html 

http://withfriendship.com/user/neeha/ascaris.php

http://www.parasitesinhumans.org/wuchereria-bancrofti-lymphatic-filariasis.html

Info:

http://www.mcwdn.org/Animals/Roundworms.html 

http://www.earthlife.net/inverts/nematoda.html 

http://nematode.unl.edu/reproduc.htm