Flustrellidra corniculata Smitt, 1871

Common name(s): Seaweed muffs

Synonyms:  Flustrellidra cervicornis, Flustrella corniculata
Phylum Bryozoa
 Class Gymnolaemata
  Order Ctenostomata
   Suborder Euctenostomata
    Family Flustrellidridae
Flustrellidra corniculata at Kalaloch, WA
(Photo by: Dave Cowles, July 2005)
Description:  As a member of Class Gymnolaemata, Order Ctenostomata this species has zooecia which are uncalcified.  Flustrellida corniculata colonies form a fleshy, leathery, erect (sometimes encrusting on seaweed) structure of soft, flattened lobes and covered with many forked, antlerlike spines.  The color is pale tan to dark brown.  Microscopically, the lophophores extend through slitlike apertures that are less distinct than those of most bryozoans (partly because most bryozoans have a glassy or calcified covering while this species, and other Ctenostomatans, does not).  Each lophophore has 18 tentacles.  The autozooids are 0.4 to o.6 mm wide.  Other zooids, called kenozooids, are smaller and bear the branched spines.

How to Distinguish from Similar Species:  There are no similar species in this area.

Geographical Range:  Alaska to Point Buchen, central CA

Depth Range:

Habitat:  Attached in the lower rocky intertidal, or as sheaths on the stipes of seaweeds such as Laminaria spp. and Corallina officinalis.

Biology/Natural History:  These colonies often wash ashore on exposed beaches during storms, and look a bit like seaweed.

Corniculata means "having little horns".

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Dichotomous Keys:
  Kozloff 1987, 1996
  Smith and Carlton, 1975

General References:
  Brusca and Brusca, 1978
  Kozloff, 1993
  Morris et al., 1980
  O'Clair and O'Clair, 1998
  Ricketts et al., 1985

Scientific Articles:

Web sites:

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

The forked spines can be seen in this closeup photo

Flustrellidra corniculata is frequently found growing on algae.  At Beach #4 near Kalaloch many can be found growing on Laminaria holdfasts such as this example.
Photo by Dave Cowles July 2008

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