Other Taxonomic Groupings
is an erect, arborescent bryozoan whose colonies form brown or reddish tufts
on whatever substratum they encounter. It is a common and abundant member of
the fouling community (Winston 1995). Zooids are large and measure an
average of 0.97 X 0.28 mm. Zooids alternate biserially on branches, with
individual zooids tapering proximally. A membrane covers the frontal
surface. B. neritina differs from other species in this genus in that
it possesses no avicularia and no spines. Rather, its zooids have sharp
points in the distal corners. The lophophore measures an average of 0.764 mm
in diameter and bears 23 tentacles.
HABITAT AND DISTRIBUTION
B. neritina is
a highly cosmopolitan and abundant species throughout warm water areas of the
world and is considered a troubling fouling organism.
occurs throughout the Indian River Lagoon and along the Florida coast.
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Zooids are large and measure an average of 0.97 X
0.28 mm. The lophophore measures an average of 0.764 mm in diameter and bears 23
B. neritina is
one of the most abundant bryozoans in the IRL and an important member of the
fouling community. It is most common in the winter months where it and B.
stolonifera dominate bryozoan populations on hard substrata such as seawalls
and docks (Winston 1995). It does however, show a fluctuating pattern of
abundance. In some years it is a dominant species from late fall through late
spring. In other years, it is sparsely distributed.
B. neritina has
large ovicells that are attached to the distal corners of zooids and oriented at
angles to the axis of the branch. In temperate waters, B. neritina
reproduces in summer and fall. In the IRL, reproduction occurs in the cooler
months. Older colonies appear to "over-summer." Winston (1982)
reported that colonies collected coastally in June and July were brown in color
and appeared to be nearly completely degenerated, with many zooids dead or
filled with ciliates. However, closer examination revealed functional zooids
present in the distal ends of the colony.
Embryos brooded in ovicells are dark brown in color
and measure approximately 0.25 mm in diameter (Winston 1982).
Though B. neritina is eurythermal, it can be
sensitive to cold. Winston (1982) reported that Bugula neritina colonies
collected from intertidal areas of Sebastian Inlet after a cold event were all
dead. This sensitivity to cold water temperatures may help to explain the
fluctuating abundance pattern in this species.
Winston (1978) reported that B. neritina has
apparently developed an adaptation for feeding on zooplankton. By twisting the
ends of its tentacles together to form a cage of sorts, B. neritina is
able to filter out active ciliates and other protists.
like all bryozoans, is a suspension feeder. Each individual zooid in a colony
has 23 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).
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,
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. 1978. Polypide morphology and feeding behavior in marine ectoprocts. Bull Mar Sci 28: 1-31.
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