Zooids are arranged uniserially, with each polypide functioning somewhat
independently of its neighbors. Individual zooids are large, oval or teardrop in
shape, and their growth pattern tends to obscure the stolon. Zooids measure
approximately 0.50 X 1.45 mm and are generally yellow to brown in color. The
lophophore measures an average of 0.820 mm in diameter, and bears 31 tentacles,
thus making it one of the larger species of bryozoans studied.
Synonymy:
Victorella sibogae
Harmer, 1915
Other Taxonomic Groupings:
Suborder: Carnosa
Superfamily: Paludicelloidea
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
In the western Atlantic, S. sibogae occurs
from Beaufort, South Carolina south through Florida and the Gulf of Mexico to
Brazil.
IRL Distribution:
S. sibogae has
been collected from Haulover Canal, Titusville and also at sites along the
coast.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids measure 0.5 X 1.45 mm. The lophophore has 31
tentacles and measures approximately 0.82 mm in diameter.
Abundance:
S. sibogae is
likely to occur year-round in the Indian River Lagoon, but is not considered
abundant.
Locomotion:
Sessile
Reproduction:
Reproductive season in this species is not known
(Winston 1982).
Embryology:
The embryology of S. sibogae is unknown.
IV. PHYSICAL TOLERANCES
Temperature:
Because S. sibogae is likely to occur year-round in the IRL, it
is considered eurythermal.
Salinity:
S. sibogae is
collected coastally and within the Indian River Lagoon where salinity exceeds 30‰
(Winston 1982).
V. COMMUNITY ECOLOGY
Trophic Mode:
S. sibogae,
like all bryozoans, is a suspension feeder. Each individual zooid in a colony
has 31 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 could clear
8.8 ml of water per day.
While actively feeding, the entire introvert, as well
as the superior portion of the flexible zooecium of S. sibogae, scan back
and forth constantly. This species also feeds by tentacle flicking, in which
each tentacle is slowly bent in to approximately ½ its length, then slowly bent
back out. By using tentacle flicking in conjunction with ciliary action, this
species is able to concentrate particles into a bolus that is then directed
towards the mouth. The food bolus is maneuvered around the mouth, and the
polypide eventually retracts into the zooid, taking the bolus with it.
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). S. sibogae is typically found as tiny
encrustations on Syringodium and other seagrasses, algae, and the roots
of hydroids.
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
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