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
Submit additional information, photos or comments to:
irl_webmaster@si.edu
Page last updated: July 25, 2001
|
