Bootlace and Annelid worms

Phylum- Nemertea

Bootlace or ribbon worms, bilateral triploblastic lophotrochozoans, feed with hollow muscular snout, mostly carnivores & inject toxins, digestive tract with mouth and anus, blood circulates in vessels, Protonephridia for excretion, long nerve cords

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Phylum- Annelida

'Little ring', metameric (repeated) segments, body wall with longitudinal and circular muscles, large coelom lined with mesodermal epithelium, thin body wall (gas diffusion, needs to be moist)

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Describe locomotion in annelids

Undulate (smooth wave motion) to swim, fluid in coelom acts as hydrostatic skeleton & enables muscles to work against each other

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Name the 3 classes in annelida

Oligochaeta, Hirudinea, Polychaeta

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Oligochaeta

Earthworms & some other terrestrial worms, 4 bundles of chaetae (segment)

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How do earthworms reproduce?

Clitellum becomes sac for eggs, hermaphrodites, worms lie side by side head to tail and exchange sperm

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Hirudinea

Leeches, sucker at each end, no chaetae, 3 jaws, secrete anticoagulant, hirudin and anaesthetic to stop blood clot and host feeling anything

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Polychaeta

'Many bristles', nearly all marine, soft sediment, filter prey, stiff chaetae to provide traction, most have separate sexes

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What are 2 examples of reproductive strategies in Polychaeta?

Environmental sex determination (2 females, chemical from larger female causes smaller to change to male), Epitoky (segments fill with gametes -Epitokes- and these split off and burst releasing gametes, epitokes can sometimes be to whole worm)

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Bootlace and Annelid worms

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