Species Description:
W. subovoidea is a calcified, encrusting
bryozoan. Its colonies are variable in appearance, and may be unilaminar
and encrusting, to bilaminar and frilled. Living specimens are
brownish orange to black. Polypides are bright orange-red. Zooids are
large, and irregularly shaped, measuring an average of 0.82 X 0.38 mm in size.
The frontal surface is curved and evenly perforated by large pores. The orifice
is oval anteriorly with a small semicircular sinus which lends an overall
mushroom-shaped appearance to the orifice. The operculum is generally dark brown
to black. No avicularia are present. Average lophophore diameter is
approximately 0.66 mm. An average of 21 tentacles is present on the lophophore.
Synonymy:
Cellepora subovoidea d'Orbigny, 1852
Lepralia cucullata Osburn, 1914
Watersipora cucullata Hastings, 1930
Dakaria subovoidea: Harmer, 1957
Other Taxonomic Groupings:
Suborder: Ascophora
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
W. subovoidea synonymy is very confused,
however, this species appears to be highly cosmopolitan in warm waters. In
the western Atlantic, it ranges from Florida south to Brazil, including the Gulf
of Mexico and the Caribbean.
IRL Distribution:
W. subovoidea is the most common encrusting
bryozoan along the coastline.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids measure an average of 0.82 X 0.38 mm in
size. Lophophore diameter is approximately 0.66 mm. An average of 21 tentacles
is present on the lophophore.
Abundance:
W. subovoidea is one of the most abundant
bryozoan species in the IRL and along the coast of Florida. It is also among the
most common fouling organisms in this area. It is present year-round, but is
most abundant in the winter months. Its success as a fouling organism is
attributed to its rapid growth rate and its ability to grow on nearly every hard
substratum including those coated with copper antifouling paint (Wisely 1958 in
Winston 1982). W. subovoidea is most abundant on the rocks of breakwaters
at or near the mean low water level.
Locomotion:
Sessile
Reproduction:
W. subovoidea reproduces from November to
April, with peak abundance of larvae in November and December.
Embryology:
No ovicells are present in this species. Rather,
embryos are brooded in internal ovisacs.
IV. PHYSICAL TOLERANCES
Temperature:
W. subovoidea is present in the IRL and
along the coast year-round, and thus may be considered eurythermal.
Salinity:
In the IRL, W. subovoidea is commonly
collected in areas where salinity falls below 30‰.
V. COMMUNITY ECOLOGY
Trophic Mode:
W. subovoidea, like all bryozoans, is a
suspension feeder. Each individual zooid in a colony has 21 ciliated tentacles
which 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.
Competitors:
W. subovoidea, like other encrusting types
of bryozoan, competes for space with other groups of attached organisms such as
algae and hydroids. In calm waters, or in areas where competition for space is
intense, W. subovoidea grows as bilaminar frills. In high energy areas,
or where there is less competition for space, it grows as unilaminar crusts.
Habitats:
Typical habitat for ectoprocts in the Indian River
Lagoon include seagrasses, drift algae, oyster reef, docks, pilings,
breakwaters, and man-made debris (Winston 1995). W. subovoidea is common
on the rocks of breakwaters, and is the only encrusting bryozoan that grows on
"wormrock," the cemented sand tubes of Phragmatopoma lapidosa,
the reef-building sabellarid.
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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