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Related FAQs: Sea Pens

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Sea Pens and Pansies, Order Pennatulacea

Bob Fenner

Cavernularia cf. obesa 

Though they look sluggish, primitive, these are specialized animals, well-adapted to their soft sediment based lives. Like icebergs you are only seeing part of the story when observing them, for another part other than the "above ground" rachis, the feeding mechanism, exists below... the muscular peduncle, anchoring the colonial animal to the sea bottom. 

Sea Pansies:

Renilla koellikeri in the Sea of Cortez; L.A. Bay. 

Renilla reniformisi in Bonaire, night dive. 

Sea Pens:

    The majority of sea pens are comprised of a singular stalk, incorporating calcium carbonate sclerites for structure, with varying polyps, branches that may be evidenced only when these animals are actively feeding. Many are nocturnal. 

Genus Cavernularia: Cylindrical, sausage shaped; with large polyps around the entire rachis (upper end)

Cavernularia cf. obesa Valenciennes in Milne Edwards & Haime 1850. Sausage-shaped overall. Large polyps extend all around rachis. India to Eastern Pacific. Possibly 14 species in this genus, some photosynthetic and open during the day, others nocturnal. Aquarium pix at a marine livestock wholesaler. 

Cavernularia sp.  Sausage-shaped overall. Large polyps extend radially around rachis. To 15 cm. W. Pacific. Bali 2014

Pteroides sp. A large (up to 60 cm. tall), stiff species, with brush-like lateral branching. Often found with the commensal crab Porcellanella picta in association. Twenty five plus valid species. Europe; Mediterranean, Indo-West Pacific; Africa to Japan. N. Sulawesi pic.

Ptylosarcus gurneyi (J. E. Gray), the Fleshy/Orange Sea Pen. Here at the Shaw Centre, Victoria, B.C., Canada 2010

Genus Virgularia:

Virgularia sp. 1 A white and purple wide feather-like species. To 8-60 cm. in height. Indo-West-Pacific; Bali 2014

Virgularia sp. 2 A tan feather-like species. To about 25 cm. in height.  West-Pacific; Philippines. N. Sulawesi pic.

Virgularia sp. 3 A red and tan feather-like species. To about 10 cm. in height. Nocturnal. West-Pacific; Philippines. N. Sulawesi pic.

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