Species Description: 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.
Regional Occurrence: A. palmata is a highly cosmopolitan species, occurring in the western Atlantic from Massachusetts south to the Gulf of Mexico, the Caribbean and Brazil.
IRL Distribution: 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).
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).
Abundance: 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).
Embryology: The embryology of A. palmata is unknown.
Temperature: Due to its cosmopolitan distribution, A. palmata is considered eurythermal.
Salinity: Winston's (1982, 1995) studies have shown that A. palmata is collected in areas where salinity is typically above 30‰
Trophic Mode: 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.
Habitats: 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.