PHYLUM NEMATOMORPHA(nema, thread + morphe, form)

Nematomorphs are a small group of about 250 species. They are elongated worms. They are commonly called horsehair worms or Gordian worms.

Habitat: The adults are free-living. But juveniles are all parasitic in arthropods.They have a worldwide distribution. They are found in both running and standing water.

Body form: The nematomorph body is extremely long and threadlike. They have no distinct head.

Body wall: The body wall has a thick cuticle, a cellular epidermis and longitudinal cords. It also has a muscle layer of longitudinal fibers.

Nervous system: The nervous system contains an anterior nerve ring and a ventral cord.

Reproduction: Nematomorphs have separate sexes. Two long gonads extend the length of the body. The eggs are deposited in water.



Development: A small larva is hatched. It has a protrusible proboscis armed with spines. Terminal stylets are also present on the proboscis. The larva must quickly enter an arthropods (e.g. a beetle cockroach) host. It enters the host by penetrating the host or it is eaten by arthropod. Larva lacks a digestive system. The larva absorbs material directly across its body wall. The larva becomes mature. It leaves its host only when the arthropod is near water. The free-living adult form becomes sexual mature.

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