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Echinoderms - sea stars, sea urchins, sea cucumbers, brittle stars


Pisaster ochraceusPisaster ochraceus (Brandt, 1835)

Phylum Echinodermata, Class Asteroidea, Order Forcipulatida, Family Asteriidae

Common sea star; arm radius to 15 cm; stout tapering arms; short white spines in reticulate pattern; color yellow, pale orange, dark brown, or purple.

Abundant, mid- to low intertidal zones & subtidal, exposed outer coast. Important predator on mussels, snails.

Geogr. Range: Alaska to southern California
Synonyms:
Similar species: subtidal spp.: Pisaster giganteus has blue rings around white or purple spines;  P. brevispinus is pink with small white spines.

 

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Leptasterias aequalisLeptasterias aequalis (Stimpson, 1862)

Phylum Echinodermata, Cass. Asteroidea, Order Forcipulatida, Family Asteriidae

Six armed sea star; arm radius to 4 cm; mottled green, purple or red with irregular white bands.

Common in pools & under rocks, mid- & low intertidal zones & subtidal; protected outer coast. Generalist predator, feeds on small snails, small mussels & barnacles, sea cucumbers. In winter, females brood eggs to juvenile stage under oral disc and do not feed during incubation.

Geogr. Range: Puget Sound to southern California
Synonyms: formerly referred to as Leptasterias hexactis, which is probably a northern species.
Similar species: the small 6-armed sea stars of the Pacific coast are a complex of species that are difficult to distinguish in the field.

 

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Patiria miniataPatiria miniata (Brandt, 1835)

Phylum Echinodermata, Class Asteroidea, Order Valvatida, Family Asterinidae

Bat star; short broad triangular arms; color varies from solid orange to red, mottled cream, or blue; individuals with 6 or even 7 arms are fairly common.

Very common, low intertidal zone & subtidal; exposed & protected outer coast.  Omnivorous detritivore.

Geogr. Range: Alaska to Baja
Synonyms: Asterina miniata
Similar species:

 

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Henricia "leviuscula"Henricia "leviuscula"  (Stimpson, 1857)

Phylum Echinodermata, Class Asteroidea, Order Spinulosida, Family Echinasteridae

Slender arms, radius 2-3 cm (larger subtidally); color varies from uniform red-orange to mottled orange, pink & red.

Common but cryptic, in tidepools & under rocks; lower mid- to low intertidal zones and subtidal. Feeds on sessile invertebrates (bryozoans, tunicates, sponges), as well as bacterial films & fine particulate matter.

Geogr. Range: Aleutian Islands, Alaska to Baja
Synonyms:
Similar species:
several subspecies or varieties are recognized; this is probably a complex of several species.

 

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Amphiodia occidentalisAmphiodia 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.

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

 

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Strongylocentrotus purpuratusStrongylocentrotus purpuratus (Stimpson, 1857)

Phylum Echinodermata, Class Echinoidea, Subcl. Euechinoidea, Order Echinoida, Family Strongylocentrotidae

Purple sea urchin; test 5 cm diameter (10 cm max), spines short (usually < half diameter of test). Small juveniles often white.

Common in pools, crevices, under rocks; mid- to low intertidal zones & subtidal; exposed & protected outer coast. Herbivorous with a strong preference for giant kelp.

Geogr. Range: Alaska to Baja
Synonyms:
Similar species: Mesocentrotus franciscanus is larger, more red, occurs subtidally.

Image: Leptasterias aequalis (upper left); Chlorostoma funebralis (lower rt.)

 

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Leptosynapta albicansLeptosynapta albicans (Selenka, 1867)

Phylum Echinodermata, Class Holothuroidea, Order Apodida, Family Synaptidae

Wormlike sea cucumber lacking tube feet; white or pale tan, 5-15 cm long; 5 longitudinal muscle bands visible through body wall of relaxed animal with 10 branched oral tentacles surrounding mouth.

Common, under rocks on course sand or shell rubble; mid- to low intertidal zones; protected outer coast; burrowing deposit feeder.

Geogr. Range: northern limit uncertain, but at least central Calif. to Baja
Synonyms:
Similar species:
5 spp. of Leptosynapta occur along West Coast.

 

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Lissothuria nutriensLissothuria nutriens (Clark, 1901)

Phylum Echinodermata, Class Holothuroidea, Order Dendrochirotida, Family Psolidae

Small sea cucumber, 1.5-2 cm long; dorsal surface bright red-orange or scarlet w. scattered tube feet, ventral side pale and flattened w. clear rows of tube feet; ten unequal tentacles around mouth (8 large, 2 small).

Moderately common but inconspicuous, on rocks or in sand around holdfasts or sea grass; low intertidal zone to subtidal; broods young in shallow depressions on dorsal surface.

Geogr. Range: Monterey Bay to southern California
Synonyms:
Similar species:

 

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Cucumaria pseudocurataCucumaria pseudocurata Deichmann, 1938

Phylum Echinodermata, Class Holothuroidea, Order Dendrochirotida, Family Cucumariidae

False tar spot sea cucumber; 1-3 cm; dorsal dk. brown to light brown or yellowish-gray; tube feet in 5 zig-zag rows along body; 8 large & 2 small tentacles around mouth, all darker toward tips.

Locally abundant, but spotty; often amongst mussels or corallines; mid- to low intertidal zones, exposed & protected outer coast; females brood young.

Geogr. Range: British Columbia to Monterey Bay
Synonyms:
Similar species:
Pseudocnus curatus is very similar, but has scattered tube feet & 10 equal tentacles; must examine skin ossicles to confirm.

 

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Pseudocnus curatusPseudocnus curatus (Cowles, 1907)

Phylum Echinodermata, Class Holothuroidea, Order Dendrochirotida, Family Cucumariidae

Tar spot sea cucumber; 1-3 cm; black; tube feet scattered across dorsum, but in more distinct rows on ventral side; 10 equal-size tentacles around mouth.

Locally abundant, but spotty; low intertidal zone to subtidal, very exposed outer coast; females brood young.

Geogr. Range: probably British Columbia(?) to central California
Synonyms: Cucumaria curata
Similar species: Cucumaria pseudocurata is very similar, but has dorsal tube feet in rows & 8 large + 2 small tentacles; must examine skin ossicles to confirm.

 

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