Seanet Mid Intertidal

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Amphiodia occidentalis  (Lyman, 1860)
Phylum Echinodermata, Class Ophiuroidea, Order Ophiurida, Family Amphiuridae

Brittle star.  Disc to 12 mm diameter w. arms 9-15 times disc diameter; arm segments each with clusters of 3 short spines on each side; gray.

Moderately common but cryptic, under rocks resting on sand or in sea grass roots; mid- to low intertidal zones, protected coast.  Can shorten arms into accordion-like squiggles when disturbed; when removed from water, coils arms tightly atop disc; burrows quickly, sinking bodily into sand as podia pass sand grains up quickly to cover aboral surface; deposit feeds or may suspension feed with exposed arm tips.

Geo Range: Alaska to San Diego
Synonyms: Diamphiodia occidentalis
Similar species:  most other local brittle stars have shorter arms relative to disc diameter.