Phylum Cnidaria : Rocky Shore Anemones, Corals, Hydroids

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Anthopleura elegantissima
Anthopleura elegantissima(Brandt, 1835)
Phylum Cnidaria, Class Anthozoa, Subcl. Zoantharia, Order Actiniaria, Family Actiniidae

Cloning anemone, to 6 cm in diameter (usually less); column varies  from gray-green to white, often covered with shell debris; tentacle tips green, pink, lavender, or blue.  

Moderately common, mid-intertidal zone; protected outer coast.  Forms extensive clonal aggregations; interclonal aggression produces distinct borders. Possess photosynthetic endosymbiotic zooxanthellae (most specimens are more gray-green & have a greater cover of shell debris on column than those in photograph).

Geogr. Range: Alaska to Baja
Synonyms:
Similar species: Anthopleura sola & A. xanthogrammica are both larger & neither forms clones.

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Anthopleura sola Anthopleura sola Pearse & Francis, 2000
Phylum Cnidaria, Class Anthozoa, Subcl. Zoantharia, Order Actiniaria, Family Actiniidae

Oral disc to >15 cm diameter with radiating stripes; green to dark gray-green; warts (verrucae) on column in longitudinal rows, tentacles sometimes flecked or with pinkish tips.  Column covered with shell debris.

Common; mid-intertidal zone to subtidal, protected outer coast; solitary in shallow crevices.  Possess photosynthetic endosymbiotic zooxanthellae (a dinoflagellate).

Geogr. Range: Oregon to Baja
Synonyms: formerly thought to be a solitary form of the cloning Anthopleura elegantissima.
Similar species: Anthopleura xanthogrammica lacks distinct radiating markings on oral disc and its tentacles are more uniform in color; its verrucae are more randomly arranged down its column.

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Anthopleura xanthogrammica Anthopleura xanthogrammica (Brandt 1835)
Phylum Cnidaria, Class Anthozoa, Subcl. Zoantharia, Order Actiniaria, Family Actiniidae

Oral disc to 20 cm diameter, solid green or with faint radiating lines; tentacles uniform green.  Warts (verrucae) on brown column not obviously in longitudinal rows; usually lacks heavy cover of shell debris on column. 

Common, mid- to low intertidal zones, exposed outer coast, often just below mussel beds.  Possess photosynthetic endosymbiotic zooxanthellae (a dinoflagellate).

Geogr. Range: Alaska to Baja
Synonyms: Cribrina xanthogrammica
Similar species:
Anthopleura sola is gray-green with distinct radiating lines on oral disc; its column is more completely covered with shell debris & verrucae are arranged in rows down length of column.

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Epiactis prolifera
Epiactis prolifera Verrill, 1869
Phylum Cnidaria, Class Anthozoa, Subcl. Zoantharia, Order Actiniaria, Family Actiniidae

Oral disc to 2.5 cm in diameter; brown, greenish, or dull red; with fine longitudinal lines down its column & radiating markings on oral disc; usually with brooded young of different sizes attached to base of column. 

Moderately common but patchy; lower mid-intertidal zone to subtidal, usually on sides of rocks or undersides of overhangs, protected outer coast.  Sequential hermaphrodite (matures first as female & turns into male at larger size).

Geogr. Range: Alaska to southern California
Synonyms:
Similar species: no other anemone in Monterey broods young externally; young Anthopleura sola are greener, lack fine lines on column and do not brood young around base.

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Corynactis californica Corynactis californica Carlgren, 1936
Phylum Cnidaria, Class Anthozoa, Subcl. Zoantharia, Order Corallimorpharia, Family Corallimorphidae

Oral disc 1 cm diameter surrounded by distinctive white club-tipped tentacles.  Column & oral disc uniform in color ranging from red to orange, pink, lavender, or buff.   Forms clones that can be distinguished by color.

Moderately common, low intertidal zone to (mostly) subtidal, amongst algae & sides of rocks; protected outer coast.  Large aggregations more common subtidally.

Geogr. Range: Northern California to Baja
Synonyms:
Similar species: the cup coral Balanophyllia elegans has a CaCO3 skeleton & is more orange rather than red; its tentacles are transparent & not club-tipped.

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Balanophyllia elegans
Balanophyllia elegans Verrill, 1864
Phylum Cnidaria, Class Anthozoa, Subcl. Zoantharia, Order Scleractinia, Family Dendrophylliidae

Solitary cup corals 5-8 mm diameter; bright orange with transparent tapered tentacles.  Produces large (1 mm) non-swimming planula larvae same color as adult.

Common, low intertidal zone to (mostly) subtidal on rocks; exposed outer coast. 

Geogr. Range: Oregon to southern California
Synonyms:
Similar species: Corynactis is usually more red-orange, lacks a CaCO3 skeletal cup, & has club-tipped white tentacles.

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Aglaophenia sp.
Aglaophenia spp. Verrill, 1864
Phylum Cnidaria, Class Hydrozoa, Subcl. Leptothecata, Order Conica, Family Aglaopheniidae

Robust feather-like colony to 10 cm tall; brown, orange or tan. Rice grain-like structures (corbulae) on side branches house reproductive individuals (no free-swimming medusae). 

Moderately common, low intertidal zone to shallow subtidal, exposed & protected outer coast. Often epiphytic on Prionitis and other bushy red algae.

Geogr. Range: Alaska to southern California
Synonyms:
Similar species: many other hydroids occur in the low intertidal zone & down into the subtidal

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Page created by J.M. Watanabe
All images copyright James Watanabe unless otherwise indicated
Contact:  watanabe_at_stanford_dot_edu                                                                                                                                   Last  update: 16 February 2012