What are the characteristics and life cycle of the Phylum Nematoda?
Morphology of the Phylum Nematoda
Internal morphology: digestive tube, importance, and cycle
Importance of the Phylum Nematoda
The Phylum Nematoda is composed of pluricellular animals that can live freely in soil, freshwater, and saltwater, or as endoparasites of tissues and fluids of animals and plants, including humans.
The digestive system of nematodes is complete and permanent, with the mouth being terminal with teeth in many species, and the anus at the opposite end of the body.
Nematodes are hermaphrodites, and the fertilization is internal. The eggs are microscopic and protected by a chitinous cuticle.
The life cycle of nematodes includes copulation between male and female, gestation of the female, egg-laying inside the host, and the release of eggs outside through the host's excrement. The larvae hatch and go through five stages, with the L3 stage being the infesting stage. The L4 and L5 stages occur inside the host, with L5 being the mature sexually differentiated nematode that can mate.
Nematodes can cause great losses to the economy when there is a high degree of infestation. Many species are parasites of humans and domestic animals, decreasing the efficiency and economic value of the host or causing diseases and even death.