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Description:
Aetea truncata
colonies consist of creeping stolons from which individuals of the colony
arise. Colonies are typically white to creamy yellow in color.
Individuals of a colony, called zooids, are tubelike in appearance.
The lower portion of each zooid, where it is attached to the stolon, is
somewhat plant-like. The upper portion of a zooid houses the
tentacles, which are arranged in a funnel shape around the mouth.
Opercula cover the mouth area. The tubular portion of a zooid measures approximately 0.03 X
0.002 inches. In this species, both the stolon and zooids are
studded with tiny bump-like tubercles, but no striations, as is found in a
closely related species, Aetea sica. Each individual zooid in a colony
has tentacles that are extended to filter phytoplankton from the water column.
During the reproductive season, A. truncata broods its embryos in
membranous pouches called ovisacs for a period of time before they are
released.
Habitats: A. truncata is typically collected from waters
where salinity is above 30 ‰.
Typical habitats include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters,
and man-made debris. A. truncata was collected in the
Sebastian Inlet area from the stems of the hydrozoan Thyroscyphus ramosus.
Similar species:
Aetea trucata could be mistaken for A. sica, because the growth
pattern of both species is quite similar. However, A. trucata
is studded with tubercles on both its stolon and zooids, and also lacks fine striations on the basal portion of
zooids. Conversely, A. sica has no tubercles, and is striated
on the basal portions of its zooids.
Range:
With the exception of polar seas, Aetea truncata
has a world-wide distribution. In the Western Atlantic it is most common from
Cape Hatteras south through Florida and the Gulf of Mexico to the Caribbean and
Brazil. A. truncata has
commonly been collected from the Sebastian Inlet area during November,
though it is likely to occur throughout the Indian River Lagoon.
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Photo from an electron microscope showing individuals of Aetea
truncata. Photo by J. Winston, courtesy of American Museum of
Natural History. Used with permission. |
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Studies (Bullivant 1967;
1968) have shown that the average individual zooid in a bryozoan colony can
filter approximately 1/3 ounce (8.8 ml) of water per day through its body -
an amazing feat for an organism measuring only 3/100s of an inch in height!
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