Gnathostomata (echinoid)

Gnathostomata; Temporal range: Lower Jurassic–recent PreꞒ Ꞓ O S D C P T J K Pg N
	Echinocyamus pusillus (order Clypeasteroida)
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Superorder:	Gnathostomata
Orders
	Clypeasteroida; Holectypoida

The Gnathostomata are a superorder of sea urchins, including the familiar sand dollars.

Gnathostomatans are irregular in shape, but unlike other irregular sea urchins, possess a feeding lantern. The mouth is located in the centre of the lower surface, as it is in most other sea urchins, but the anus is found to one side of the upper surface, rather than being central. The members of the group are adapted for burrowing in soft-bottomed marine environments.

References

Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 981. ISBN 0-03-056747-5.

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