Echinoderms Flashcards

1
Q

Orders of echinoderms?

A
Asteroids (starfish) 
Ophiuroids (brittle stars) 
Echinoids (sea urchins) 
Holothurians (sea cucumbers) 
Crinoids (sea lilies and feather stars)
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2
Q

Features of echinoderms?

A

Pentaradial symmetry
Water vascular system
Endoskeleton
Marine

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3
Q

What is a madreporite?

A

A perforated plate by which the entry of seawater into the vascular system of an echinoderm is controlled.

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4
Q

What is aboral?

A

End furthest from the mouth.

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5
Q

What does the water vascular system consist of?

A

A ring canal in the centre, radial canals radiating outwards with ampullae and tubefeet.

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6
Q

Features of echinoderm endoskeleton?

A

Ossicles of calcium carbonate. Brittle stars have moveable arms due to thinner arms with flexibility between ossicles.

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7
Q

Taxonomy of hemichordates?

A

Enteropneusts (acorn worms)

Pterobranchs

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8
Q

Features of acorn worms?

A

Very fragile worms.

Few cm long and in a marine environment. Burrows in sand and mud.

Holes in pharynx - pharyngeal gill slits.

Nervous system with an epidermal nerve net.

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9
Q

Features of pterobranchs?

A

Tiny (few mms). Sessile.

Sometimes live in colonies.

In a tube, on a stalk. U shaped gut. Filter feeders

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