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SEM of an older colony of A. leucocypha.  Photo by J. Winston, courtesy of the American Museum of Natural History.  
Used with permission.

Voucher Specimen: 
American Museum of Natural History 
# 590, 591

Common Name:
None

Species Description:
Colonies of A. leucocypha are encrusting in single or multiple layers, and are typically a whitish to pink or magenta color. Individual zooids are variable in shape, but are generally oval, narrowing toward the distal portion. In secondary layers, zooids may often be irregularly oriented. Zooids measure approximately 0.33 X 0.23 mm. Opesia of zooids are wider proximally, narrowing distally. Triangular spaces between typical feeding individuals (autozooids) are often filled with smaller kenozooids, calcareous deposits, solid tubercles, or tubercles that are transformed into avicularia. However, in older colonies, kenozooids and avicularia may be absent from large areas of the colony. Polypides are transparent to white in color. The lophophore measures an average of 0.326 mm in diameter, and bears an average of 12 tentacles.

Other Taxonomic Groupings:
Suborder: Anasca

Potentially Misidentified Species:
A. leucocypha is quite similar to A. tincta. Cook (1968) differentiated these species based on differences in the frequency of occurrence in kenozooids, the size of the avicularia, and on the shape of their mandibles. Winston (1982) observed that in Florida specimens of these species smaller, unilaminar colonies, which were presumed to be younger colonies, generally resembled the description for A. leucocypha. Conversely, large, multilaminar (multi-layered) colonies approached the description for A. tincta. Winston (1982) also reported differences in the texture of the cryptocysts that aided in identification.

II.  HABITAT AND DISTRIBUTION 
Regional Occurrence:
A. leucocypha occurs in warm waters of both the Atlantic and Pacific Oceans. In the Western Atlantic, it occurs most commonly from Cape Hatteras to Florida, the Gulf of Mexico and the Caribbean.

IRL Distribution:
A. leucocypha is collected year round in the IRL and at coastal locations. It is most common intertidally along the coast.

III.  LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids measure 0.30 - 0.35 mm in height by 0.20 - 0.25 mm in width. The lophophore measures approximately 0.326 mm in diameter and bears an average of 12 tentacles.

Abundance:
A. leucocypha is common intertidally along the coast of Florida, and can be found year round within the IRL in areas where salinity is above 30‰ (Winston 1982).  

Locomotion:
Sessile

Reproduction:
Endozooidal Ovicells are present in A. leucocypha.   Opercula of both fertile and sterile zooids are highly variable, thus fertile zooids are sometimes difficult to detect (Winston 1982).

IV.  PHYSICAL TOLERANCES
Temperature:
Because it can be collected in the IRL year round, A. leucocypha is considered to be eurythermal.

Salinity:
A. leucocypha is typically collected in areas of the IRL where salinity exceeds 30‰ (Winston 1982).

V.  COMMUNITY ECOLOGY
Trophic Mode:
A. leucocypha, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has an average of 12 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. leucocypha typically encrusts gastropod shells. Unilaminar colonies are generally found on living gastropods, while multilaminar colonies are often found on dead gastropod shells inhabited by hermit crabs.

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