Describe The Characteristics Of The Animals Included In Phylum Nematode?


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1. The meaning of nematoda is "pointed ends". The animals included in this grioup have elongated worm like body with pointed ends.
2. The nematodes are triploblastic and psudocoelomates.
3. One end of the body is anterior, however the head is not clearly marked and there are no special sense organs at this end.
4. The nematodes exhibit bilateral symmetry and the body is unsegmented.
5. The body cavity is pseudocoelom. It is derived from the hollow space, the blastocoel, situated in the blastula, an early stage in embryological development, and not from the mesoderm.

6. The nematodes range in size from small microscopic forms, to some forms reaching a length up to one meter.
7. The digestive system is in the form of alimentary canal with two openings. The opening at the anterior end is mouth and at the back end is anus. In parasitic nematodes the digestive system is simple.
8. A fluid filled space is present between the body wall and alimentary canal. It provides tube with in the tube type structure in nematodes.

9. The excretory system consists of two longitudinal running canals which unit to form a single canal and open to the excretory pore.
10. Circulatory and respiratory systems are absent.
11. Sexes are separate. Fertilization is internal.

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