Nematoda
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General characteristics of nematodes
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Nematoda
- 1. Nematoda
- 2. Nematoda From the Greek word Nema for thread Commonly known as roundworms There are more than 15, 000 known species of round worms.
- 3. Taxonomy Kingdom Animalia Phylum Nemadota Class Adenophorea Secernentea
- 5. Multicellular Body covered in a complex cuticle. Has a nervous system with pharyngeal nerve ring. Body cavity is a pseudocoel, body fluid under high pressure. Body possesses a through gut with a subterminal anus.
- 7. Movement
- 8. Feed on just about everything. Nematodes can be herbivorous, carnivorous, or parasitic. They can be both generalists and specialists
- 9. Live just about everywhere, many species are endoparasites. They are found in almost everywhere, terrestrial, fresh water, salt water, and in other organisms as parasites. Nematodes that live in other organisms are called Parasitic Nematodes that don’t live in other organisms are called Free Living
- 10. Reproduction normally sexual. Separate sexes Males have specialized spine for sexual reproduction that is used to inject sperm. Sperm cells do not have flagella and moves using an amoeboid motion Some species are live-bearing, most lay eggs. Eggs, escape through a mid-body hole called the gonomore in the female
- 11. Egg cycle Larva stages L1 – develops inside the egg, hatches, then molts to L2 L2 – shows rapid growth followed by a second molt L3 – the infective stage for may species of nematodes, then molts inside the host to L4 L4 – grows then undertakes final molt to an immature adult L5 – final growth phase and becomes sexually mature.
- 12. Molting Synthesis of a new cuticle by the hypodermis. At this stage, the larva is still covered by the old cuticle. Exsheathment is a process by which the old cuticle is loosene and ruptured, followed by the larva wriggling out of the casting of the old cuticle.
- 13. Ecological importance They play a role in decomposition and nutrient cycling, where they are often the intermediate decomposers that partly break down organic materials so that they can then be dealt with by bacterial decomposers
- 14. Economic importance Nematodes are used for gardening. They would destroy pests. Upon entering their hosts or target pest, they release bacteria that would kill that pest.
- 15. Class: Adenophorea Order: Stichosomid Super family: Trichocephaloidea Family: Trichinellidea Scientific Name: Trichinella spiralis Tropical parasites Responsible for Trichinosis Responsible for elephantiasis and river blindness Uses pigs humans and other mammals as hosts
- 16. Class: Secernentea Order: Strongylida Family: Strongyidae Scientific Name: Strongylus vulgaris Also known as blood worm Usually in the large intestines Causes diarrhea, colic, moderate normocytic, normochromic anemia Infects the iliac artery that may lead to temporary lameness.
- 17. Class: Adenophorea Subclass: Chromadorea Order: Rhabditida Family: Rhabditidae Scientific Name: Caenorhabditis elegans Free living Most studied nematode Non-hazardus, non-infectious, non-pathogenic, non-parasitic First multicellular organism where a complete DNA sequence was obtained. Served as a biological model organism for genetic developmental studies.