Other Taxonomic Groupings
American Museum of Natural History
Colonies of A. sica consist
of creeping stolons from which erect tubular portions arise. These typically
measure from 0.1 - 1.8 mm in height. The basal portions of tubes are marked
with fine annulations. Tubular portions of zooid are slightly expanded at
the aperture. Proportion of this "head" region to the stolon
region is approximately 1:3 (Winston 1982).
Potentially Misidentified Species
A. sica could be mistaken for A. truncata, because both species
have a similar growth pattern where stolons widen into zooid bases from which
tubular portions arise. However, A. sica has a pattern of fine
annulations on its basal portions that is not seen in A. truncata.
HABITAT AND DISTRIBUTION
A. sica is highly cosmopolitan,
with wide distribution except in the polar regions. In the Western
Atlantic, it commonly occurs from Cape Hatteras south through Florida, the Gulf
of Mexico, and the Caribbean to Brazil.
Within the IRL, A. sica has been
collected from seagrass beds and from the red algae Solieria tenera.
Coastally, it has been collected at Ft. Pierce Breakwater, Walton Rocks and
Seminole Shores on drift algae (Sargassum), attached algae, and bushy
bryozoans (Amathia, Zoobotryon, Bugula, etc.) (Winston 1982).
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
The erect tubular portions of zooids measure
approximately 0.1 - 1.8 mm in height.
A. sica has been collected in the IRL from
February through October, with peak abundance in September and October.
Reproductive season in this species is unknown
Embryos are brooded externally in a membranous
Given its early world-wide distribution, A. sica is considered eurythermal.
A. sica, 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.
Typical habitat for ectoprocts in the Indian River
Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters,
and man-made debris (Winston 1995). A. sica was most commonly found in
association with seagrasses, marine drift algae such as Sargassum, and
with attached algae and other bryozoans such as Amathia, Zoobotryon, and Bugula
species (Winston 1982).
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,
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
Winston JE. 1982. Marine bryozoans (Ectoprocta) of the Indian River area (Florida). Bull Amer Mus
Nat Hist 173: 99-176.
Winston JE. 1995. Ectoproct diversity of the Indian River coastal lagoon. Bull Mar Sci 57: 84-93.
Report by: K. Hill, Smithsonian Marine Station
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Page last updated: July 25, 2001