Species Description:
Colonies of V. pavida develop as chains
of zooids connected by the stolon that arises from the base of new
zooids. In young colonies, overall morphology of the colony is quite simple;
however, as they develop, zooids elongate and bud off new stolons and zooids to
form extensive networks. Individual zooids are cylindrical and measure
approximately 0.15 X 0.60 mm. In older colonies, zooids can measure as much as 2
- 3 mm (Winston 1982). The lophophore averages 0.37 mm in diameter and bears 8
tentacles.
Synonymy:
None
Other Taxonomic Groupings:
Suborder: Carnosa
Superfamily: Paludicelloidea
Potentially Misidentified Species:
Colonies of V. pavida resemble those of the
genus Bowerbankia. These groups are differentiated based on differences
in growth from the stolon. In Bowerbankia, new zooids are budded
separately from the stolon; in Victorella pavida, the stolon arises from
the base of zooids.
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
V. pavida is a cosmopolitan species whose
range in the western Atlantic extends from Chesapeake Bay to Brazil.
IRL Distribution:
Prior to Winston's (1982) study, this species had
not been documented in the IRL. During the study, it was collected only once, at
Link Port, approximately 7 miles north of Ft. Pierce Inlet, but it is likely to
be distributed in brackish areas throughout the IRL (Winston 1982).
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Individual zooids measure 0.15 X 0.60 mm on
average, but can be 2 - 3 mm in older colonies. The lophophore measures
approximately 0.37 mm in diameter.
Abundance:
While this species can be locally abundant
throughout its range, it is considered rare in the Indian River Lagoon. Winston
(1995) reported it as a fouling organism in the IRL.
Locomotion:
Sessile
Reproduction:
The reproductive period of this species is not well
described.
Embryology:
V. pavida is a member of the Order
Ctenostomata that broods its embryos.
IV. PHYSICAL
TOLERANCES
Salinity:
Of the 36 known bryozoans in the Indian River
Lagoon, V. pavida is one of only 3 brackish water bryozoans. The other 33
are collected from waters where salinity generally exceeds 30‰ (Winston 1982).
V. COMMUNITY ECOLOGY
Trophic Mode:
V. pavida, like all bryozoans, is a
suspension feeder. Each individual zooid in a colony has 8 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.
Habitats:
In the IRL, V. pavida was collected only
from seagrass beds around Link Port.
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 supporting substrata: 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
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