Nematodes Flashcards
Why are Nematoda and Arthropoda placed in the superphylum Ecdysozoa?
Both groups grow by moulting. As a result, nematodes are more closely related to arthropods than annelids!
Why are nematodes important?
Model organisms for studying nervous systems.
Links to many diseases.
Vast population.
Describe the nematode body plan.
‘tube within a tube’.
Non-segmented tapering at both ends.
Longitudinal muscle for locomotion.
No blood or circulatory system.
Are nematodes free-living or parasitic?
Both.
Are nematodes diecious or hermaphroditic?
Mainly diecious.
What are the modes of reproduction in nematodes?
Viviparous (produce larvae/embryos).
Oviparous (lay eggs).
Ovo-viviparous (eggs which immediately hatch).
Why are nematodes so successful?
They possess a tough external cuticle combined with high internal pressure and they can enter cryptobiosis.
What are the layers of the nematode cuticle?
Outer layer > Middle layer > Fibrous layers > Basal layer
What is the function of the cuticle and what cells secrete them?
They are secreted by epidermal cells.
They resist penetration and enzymatic digestion.
They maintain internal hydrostatic pressure.
Describe nematode locomotion.
Sinusoidal - using whip-like undulations.
Define cryptobiosis.
A metabolic state in response to adverse environmental conditions like dessication, freezing and O2 deficiency.
What is the nematode life cycle?
Eggs.
4 juvenile stages.
Adult.
Egg production.
How can nematodes be used as biological pest control?
1) Add to soil to seek out pest.
2) Nematodes become adults in dead pests.
3) New generation produced.
4) New generation released.
How do nematodes parasitise plants?
They puncture the cell wall and inject saliva (and enzymes). The cell contents is then captured.
What are the modes of nematode infection?
Ingestion.
Skin penetration.
Blood sucking insects.
Inhalation of infected dust.
