Species Description:
E. bellula
forms encrusting colonies that are lightly calcified and transparent in
appearance. Zooids measure approximately 0.18 X 0.34 mm in size. There are
usually 2 distal spines, but possibly more, which project from the proximal gymnocyst region. A branched spine often projects over the proximal end of the
opesia. The lophophore measures an average of 0.225 mm in diameter and bears
10 tentacles.
Synonymy:
None
Other Taxonomic Groupings:
Suborder: Anasca
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
E. bellula
occurs in the western Atlantic from Florida to Brazil, including the Gulf of
Mexico and the Caribbean.
IRL Distribution:
E. bellula
occurs year round from the Ft. Pierce and St. Lucie inlet areas. It is typically
collected on seagrasses, primarily Syringodium species.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids measure approximately 0.18 X 0.34 mm in
size. The lophophore measures an average of 0.225 mm in diameter, and bears 10
tentacles.
Abundance:
E. bellula occurs
year round in the IRL. It is also collected from coastal stations (Walton Rocks)
April - July.
Locomotion:
Sessile
Reproduction:
Reproductive season is unknown in this species.
IV. PHYSICAL TOLERANCES
Temperature:
As a species that occurs year round, E. bellula
can be considered a eurythermal species, as it must withstand seasonal
fluctuations in water temperature.
Salinity:
E. bellula is
typically collected from Indian River Lagoon sites where salinity measures below
30‰.
V. COMMUNITY ECOLOGY
Trophic Mode:
E. bellula,
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 ectoprocts in the Indian River
Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters,
and man-made debris (Winston 1995). E. bellula is generally found in
association with Syringodium spp., however, it has also been collected
coastally from April to July attached to brown algae (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.
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
Submit additional information, photos or comments to:
irl_webmaster@si.edu
Page last updated: July 25, 2001
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