Species Description:
Colonies of S. regularis are erect and
branching, forming short pink tufts on various substrata.
Zooids are narrow in
the proximal portion, wider distally. The opesia are ovoid in shape, and occupy
approximately 2/3 of the frontal area. Individual zooids measure an average of
0.51 X 0.20 mm. There are 2 - 7 distolateral spines, simple or branching,
present around the mural rim. The innermost proximal spine in specialized to act
as a shield or scutum over the membranous frontal area. This single spine covers
most of the opesia, is large and paddle-shaped with pointed edges. Polypides
have obliquely truncate lophophores which average 0.464 mm in diameter.
Lophophore bears 13 tentacles that are somewhat translucent, and pink in color.
There are avicularia on the inner sides of gymnocysts, and on the outer sides of
individual zooids at the same level as the opesia. This species also possesses
short, delicate vibraculae located on the posterior-proximal surface of
each zooid.
Synonymy:
Cellularia cervicornis
Smitt, 1872
Other Taxonomic Groupings:
Suborder: Anasca
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
S. regularis
occurs in the Western Atlantic from Cape Hatteras and Bermuda south through
Florida, the Gulf of Mexico and the Caribbean. It has also been reported to
occur in the Pacific Ocean around the Gulf of California.
IRL Distribution:
In the Indian River Lagoon, S. regularis has
been documented from the grass flats around the Sebastian Inlet area. It has
also been collected coastally from Sebastian Inlet, Ft. Pierce Breakwater,
Walton Rocks, and Capron Shoals (Winston 1982).
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Individual zooids measure an average of 0.51 X 0.20
mm. Lophophore averages 0.464 mm in diameter and bears 13 tentacles.
Abundance:
S. regularis is
collected year-round, but is most common in the winter and spring months
(Winston 1982, 1995).
Locomotion:
Sessile
Reproduction:
Ovicells are present in S. regularis. These
tend to be hyperstomial and flat near the top portion with a few large pores.
Embryology:
Brooded embryos are pink to red in color. Colonies
containing both embryos and larvae have been collected March - April.
IV. PHYSICAL TOLERANCES
Salinity:
S. regularis is
typically collected from areas where salinity exceeds 30 ‰ (Winston 1995).
V. COMMUNITY ECOLOGY
Trophic Mode:
S. regularis,
like all bryozoans, is a suspension feeder. Each individual zooid in a colony
has 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 could 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). In the IRL, S. regularis has been
collected from the rhodophyte Solieria (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
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irl_webmaster@si.edu
Page last updated: July 25, 2001
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