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Voucher specimen: 
American Museum of Natural History #576

Common Name:
None

Species Description:
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).

Synonymy:
None

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.

II.  HABITAT AND DISTRIBUTION 
Regional Occurrence:
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.

IRL Distribution:
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).

III.  LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
The erect tubular portions of zooids measure approximately 0.1 - 1.8 mm in height.

Abundance:
A. sica has been collected in the IRL from February through October, with peak abundance in September and October.

Locomotion:
Sessile

Reproduction:
Reproductive season in this species is unknown (Winston 1982).

Embryology:
Embryos are brooded externally in a membranous ovisac.

IV.  PHYSICAL TOLERANCES
Temperature:
Given its nearly world-wide distribution, A. sica is considered eurythermal.

V.  COMMUNITY ECOLOGY
Trophic Mode:
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.

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). 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).

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
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Page last updated: July 25,  2001