Other Taxonomic Groupings
A. palmata is an arborescent
bryozoan whose colonies form limp, tufted tangles that are brown in color.
Zooids occur only at the tips of branches and do not bud from the sides of
mature individuals as occurs in other species. Individual zooids are
cylindrical and measure approximately 0.79 X 0.13 mm (Winston 1982). The
lophophore measures an average of 0.205 mm in diameter, and bears 10
tentacles. Colonies tend to become covered in a fine layer of silt that
makes them opaque in appearance.
Potentially Misidentified Species
A. palmata may easily be mistaken for
silt-covered marine algae. However, the presence of the lophophore helps
differentiate bryozoans from algae.
HABITAT AND DISTRIBUTION
A. palmata is a highly cosmopolitan species,
occurring in the western Atlantic from Massachusetts south to the Gulf of
Mexico, the Caribbean and Brazil.
A. palmata is likely to occur throughout the Indian
River Lagoon; however, it is considered to be most common around the Sebastian
Inlet area (Winston 1982).
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Individuals measure 0.79 mm X 0.13 mm on average,
with the lophophore measuring 0.205 mm in diameter (Winston 1982).
A. palmata is locally abundant at Sebastian
Inlet, where it can be collected between January and April. It has also been
collected as late in the year as September from the Walton Rocks area (Winston
1982). In the IRL, it is considered a fouling organism (Winston 1995).
The embryology of A. palmata is unknown.
Due to its cosmopolitan distribution, A. palmata is considered
Winston's (1982, 1995) studies have shown that A.
palmata is collected in areas where salinity is typically above 30‰
A. palmata, like all bryozoans, is a
suspension feeder. Each individual zooid in a colony has 10 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 A. palmata, especially
around the Sebastian Inlet area is on the rocks of breakwaters (Winston 1982).
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