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Species Name:    Crisia eburnea
Common Name:               (None)

 

I.  TAXONOMY

Kingdom Phylum/Division: Class: Order: Family: Genus:
Animalia Ectoprocta Gymnolaemata Cyclostomata Crisiidae Crisia


SEM of Crisia eburnea showing an enlarged gonozooid.  Photo by J. Winston, courtesy of the American Museum of Natural History.  Used with permission.  
Species Name:
Crisia eburnea (Linnaeus) 1758

Voucher Specimen: 
American Museum of American History # 632

Common Name:
None

 


Species Description:
Colonies of C. eburnea form fragile white tufts as they grow on the stems of algae. Branches curve somewhat inward, and joints are yellowish in color. Zooids are tubular and punctate, approximately 0.10 X 0.25 mm on average. The orifice comes to a point distally. This species has short internodes of 5 7 zooids.

Synonymy:
Sertularia eburnea Linnaeus, 1758
Crisia eburnea: Maturo, 1957

Other Taxonomic Groupings:
Suborder: Articulata


II.  HABITAT AND DISTRIBUTION 
Regional Occurrence:
C. eburnea is common in cold water areas from Europe through West Africa in the eastern Atlantic, and from Labrador to Florida in the western Atlantic.

IRL Distribution:
C. eburnea occurs in the IRL in association with algae and seagrasses. Within the IRL, it has been reported only from around the Sebastian Inlet grass flats; however, it is likely to occur at other locations as well.


III.  LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Individual zooids measure 0.10 X 0.25 mm on average.

Abundance:
Though C. eburnea is common throughout its range, Winston (1982) reported its occurrence only once, from the grass flats around Sebastian Inlet where it was found growing on the Rhodophyte Soliera tenera.

Locomotion:
Sessile

Embryology:
Gonozooids in C. eburnea generally occur between the fourth and fifth zooid of a fertile internode. They are elongate and roughly club shaped, but rounded distally. The oeciopore is a short tube with a transverse ovoid opening. Larvae emerging from the oeciopore remain on the parent colony briefly before entering the water column (Winston 1982).


IV.  PHYSICAL TOLERANCES
Temperature:
C. eburnea is eurythermal.

Salinity:
Within the Indian River Lagoon, C. eburnea occurs where salinity exceeds 30.


V.  COMMUNITY ECOLOGY
Trophic Mode:
C. eburnea, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has ciliated tentacles that are extended to filter phytoplankton less than 0.045 mm in size (about 1/1800 of an inch) from the water column. Bullivant (1967; 1968) showed that the average individual zooid in a colony can clear 8.8 ml of water per day.

Habitats:
Typical habitat for ectoprocts in the Indian River Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters, and man-made debris (Winston 1995). C. eburnea occurs growing on algae, and ion seagrasses. In the IRL, it has been found growing in association with the red algae Solieria tenera.

Associated Species:
Seagrasses as well as floating macroalgae, provide support for bryozoan colonies. In turn, bryozoans provide habitat for many species of juvenile fishes and their invertebrate prey such as polychaete worms, amphipods and copepods. (Winston 1995).

Bryozoans are also found in association with other species that act as support structures: mangrove roots, oyster beds, mussels, etc.


VI.  SPECIAL STATUS
Special Status:
None.

Benefit in IRL:
Bryozoans are ecologically important in the Indian River Lagoon due to their feeding method. As suspension feeders, they act as living filters in the marine environment. For example, Winston (1995) reported that bryozoan colonies located in 1 square meter of seagrass bed could potentially filter and recirculate
an average of 48,000 gallons of seawater per day.

Economic Importance:
None

 

Report by:  K. Hill, Smithsonian Marine Station
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Page last updated: July 25,  2001