Cnemidocarpa finmarkiensis Kiaer, 1893

Common name(s): Broad base sea squirt, Orange sea squirt, Red sea squirt, Shiny orange sea squirt, Shiny red tunicate, Finmark's tunicate

Synonyms:  Cnemidocarpa joannae, Polycarpa finmarkiensis, Styela elsa, Styela finmarkiensis, Styela joannae, Styela stimpsoni, Tethyum finmarkiensis
Phylum Chordata
 Subphylum Urochordata
  Class Ascidiacea
   Order Stolidobranchia
    Family Styelidae
Cnemidocarpa finmarkiensis from 15 m depth off Northwest Island.  Scale is in centimeters and mm
(Photo by: Dave Cowles, July 2005)
Description:  This solitary, unstalked tunicate has a smooth, shiny, pinkish-red opaque tunic which often looks pearly.  The shape is often approximately hemispherical.  Tunic is white when the animal is very small.  Siphons are far apart and prominent in a relaxed animal (can be more prominent than seen in the photo above).  When fully retracted the siphons look like small crosses.  Usually less than 3 cm across base though can get up to 5 cm, and up to 2.5 cm high.

How to Distinguish from Similar Species:  Other tunicates of similar shape are not usually pinkish-red, or have a wrinkled tunic.  The sea peach, Halocynthia aurantia, is a similar smooth, shiny pinkish color but it has broader siphons of unequal size and is taller than it is wide.  Of other common local smooth, orange tunicates, Metandrocarpa taylori is a social ascidian, with multiple individuals living near each other and connected by narrow stolons or sheets of tunic. Distaplia occidentalis is a compound ascidian with many individuals within the same tunic.

Geographical Range:  Alaska to Point Conception, CA; most common from Washington north.  Also northwestern Pacific, circumboreal in the Arctic

Depth Range:  Very low intertidal to at least 50 m (540 m in Japan)

Habitat:  Hard substrates in well-circulated waters.  Sometimes found on floats.  Sometimes lives in holes.

Biology/Natural History:  This species is hermaphroditic.  Fertilization is external, during the summer.  The tunic is thin but tough, with 12.4% organic content.  Just over half the organic matter in the tunic is tunicin (a carbohydrate); the rest is protein.  Vanadium content of the body is low (but higher in the tunic?)  Predators include the seastar Orthasterias koehleri.  The copepod Pygodelphys aquilonarius may live symbiotically in the branchial chamber and many invertebrates may live around the base.

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Dichotomous Keys:
  Flora and Fairbanks, 1966
  Kozloff 1987, 1996
  Smith and Carlton, 1975

General References:
  Gotshall, 1994
  Harbo, 1999
  Kozloff, 1993
  Morris etal., 1980
  Ricketts et al., 1985
  Sept, 1999

Scientific Articles:

Zeng, Liyun, Molly W. Jacobs, and Bill J. Swalla, 2006.  Coloniality has evolved once on Stolidobranch ascidians.  Integrative and Comparative Biology 46:3 pp 255-268

Web sites:

General Notes and Observations:  Locations, abundances, unusual behaviors:

In this side view one can see the two siphons (partly retracted) and some material adhering to the tunic.

In this underwater photo of Cnemidocarpa finmarkiensis near Northwest Island by Kirt Onthank (Feb 2006), the siphons are open and partly extended.  The animal above is the sea cucumber Psolus chitonoides

Another underwater photo by Kirt Onthank, July 2007

Authors and Editors of Page:
Dave Cowles (2005):  Created original page