Synapta

Eschscholtz, 1829

8 species

Tentacles pinnate, 15 occasionally 16; individuals not fully mature have 14 or fewer. Digits very numerous 15-30 on each side. Cartilaginous ring present. Polian vesicles very numerous, up to 50 and sometimes branched. Stone canals single and branched, or there may be two or even a small tuft of them. Stock of anchors finely toothed, but not branched; arms smooth, but vertex with a few minute knobs, arranged in one or two groups. Anchor plates sub-rectangular or irregular, much longer than wide, with 7 or 8 large, and numerous small holes; at posterior end, on outer side, a well arched bow crosses plate. Miliary granules abundant, but tentacles without supporting rods. (Clark, 1907)