Physical characteristics

Sea daisies have a small, discoidal, radially symmetrical echinoderm. They are circular or slightly sub-pentagonal in outline, without arms, and weakly inflated. A sea daisy has a delicately plated dorsal surface which delimits the disc-like body with a single peripheral series of flattish, oar blade-like spines. The ventral surface is dominated by a skeletal mouth frame in the form of a ring of ossicles that supports either a thin velum or a peristome opening into a shallow stomach. There are 10 large gonads, and a single peripheral ring of tube feet.

Sea daisy anatomy. (Illustration by Laura Pabst)

central plate dorsal surface plate marginal plate hydropore terminal plate inner ring canal oral frame ossicle ampula

embryos in brood pouch

"female gonad water vascular ring canal water vascular ring canal

-marginal spine "tube foot

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