Callopora horrida 

Slender-spined Bryozoan

Tegella horrida 
Membranipora horrida
Phylum Bryozoa
 Class Gymnolaemata
  Order Cheilostomata
   Suborder Anasca
    Family Calloporidae
Callapora horrida collected at Rosario Marine Station, WA
Photo by: Anna Dyer,  2002
Description:  The tan colored, encrusting colonies are up to 3 cm in diameter.  In young colonies, the gymnocyst has two or three small pores on each side, and as the colony matures, the pores enlarge.  Individuals measure 0.53 to 0.75 mm long by 0.33 to 0.50 mm wide.  Each orifice is oval and measures 0.30 to 0.40 mm long by 0.15 to 0.25 mm wide.  Two to five short, thin pointed spines lie on the proximal 2/3 of the rim of the orifice.  These bend over the orifice but are not long enough to cover it.  In addition, two pairs of straight, blunt and erect spines lay on the distal margin of the orifice near the growing edge of the colony.  In older colonies, only the more proximal pair persists.  Three or four very small pores pierce each lateral wall of the zooid, and the distal wall has a crescentic band of similar pores.  Each zooid also has a cryptocyst, a calcified wall located under the frontal membrane; this slopes and has a rough margin.  A large avicularium usually sits next to the proximal border of most orifices.  Each has a long, tapering, hooked beak that is almost parallel to the surface of the zooid and points obliquely towards the side of the orifice.  The ovicells lie beneath the surface of the zooid and in older colonies are covered by especially thick calcification and so are more difficult to see.

How to Distinguish from Similar Species:  A microscope and a dichotomous key are needed to positively identify Callopora horrida.

Geographical Range:  This species is found from Kodiak Island, Alaska, to California and in Japan Bathymetry.

Depth Range:  Found in both intertidal and subtidal zones.

Habitat:  Grows on hard substrata such as shells, stones and hard sponges.

Biology/Natural History:  No information on the biology of this particular species is known.  The following information is for Bryozoans in general.  The individuals in a colony are interconnected.  Their nervous systems are linked and nutrients can be passed from autozooids to the non-feeding heterozooids.  Most bryozoans are hermaphroditic with members of each sex within the same colony.  In most species, the embryos are yolky and the larva that develop are non-feeding.  They swim briefly but soon settle, attach to new substratum and metamorphose into the ancestrula.  In the colony, members can overgrow inferior competitors for space.  The major predators of bryozoans include pycnogonids and nudibranchs but may also be eaten by sea urchins and chitins.  Their calcification makes them unattractive prey.  Bryozoans protect themselves chemically by the formation of secondary compounds, some of which have anti-cancer properties.

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Dichotomous Keys:

  Kozloff, 1987, 1993

General References:
  O'Clair and O'Clair, 1998

Scientific Articles: 
Wollacott, Robet M. and Wheeler J. North, 1971.  Bryozoans of California and northern Mexico kelp beds.  pp. 455-479 in North, Wheeler J. (ed.), The Biology of Giant Kelp Beds (Macrocystis) in California.  Beihefts zur Nova Hedwigia Heft 32.  Publisher: J. Cramer, Lehre, Germany.

Web Sites:

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

Below are several microphotographs of Callopora horrida found on a floating, decaying eelgrass leaf in Padilla Bay. Photos by Dave Cowles, July 2020.
C horrida
C horrida

Authors and Editors of Page:
Anna Dyer (2002):  Created original page
Edited by Hans Helmstetler 11-2002