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Growth pattern of Amathia distans.
Drawing by J. Winston, courtesy of American Museum of Natural History.  
Used with permission.

Species Name: Amathia distans Busk, 1886
Common Name: None
Synonymy: None

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Ectoprocta Gymnolaemata Ctenostomata Vesiculariidae Amathia

    Other Taxonomic Groupings

    Suborder: Carnosa
    Superfamily: Vesicularioidea

    Species Description

    Colonies of A. distans appear fragile and translucent. The stolon is thin and dichotomously branching, with zooids located in clumps at intervals. Stolons and zooids are brown in color but have bright yellow pigmentation that makes living colonies appear to be yellow. Zooids are somewhat shorter than in A. alternata, and average approximately 0.4 mm in height. Zooids are arranged in double rows at the distal ends of internodes, with each set of zooids making a full or partial turn around the axis of the stolon. The growing ends of stolons often have no zooids on the first 2 internodes.


    Regional Occurrence

    A. distans is a circumtropical species and is highly cosmopolitan in warm seas. In the western Atlantic it is found from the Carolinas south through Florida and the Gulf of Mexico, to the Caribbean and Brazil.

    IRL Distribution

    In the IRL, A. distans has been collected year-round at Ft. Pierce Inlet, Walton Rocks, and Seminole Shores. It has also been taken in offshore collections from the continental shelf off Florida where it was found in association with algae (Winston 1982, 1995).


    Age, Size, Lifespan

    The stolon in A. distans is fragile and thin in appearance, measuring only 0.11 - 0.12 mm in diameter (Winston 1982). Individual zooids may grow to approximately 0.4 mm in height.


    A. distans is most abundant in the winter months in Florida, especially in December. It is not considered to be as abundant as A. alternata (Winston 1995). In the IRL, it is considered a fouling organism (Winston 1995).




    The embryology of A. alternata is unknown.



    A. distans is eurythermal. It is most abundant in Florida during the winter months, especially December (Winston 1982).


    A. distans was generally collected in areas where salinity exceeds 30� (Winston 1995).


    Trophic Mode

    A. distans, 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. distans was most commonly observed attached to rocks in the IRL or in coastal areas. It was also observed in association with algae in offshore collections (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.


    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.


    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

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