Species Description:
S. cornuta
forms encrusting colonies that are pink to salmon in color. Zooids
are oval to hexagonal and measure approximately 0.35 X 0.25 mm in size. Heavy
calcification between zooids obscures distinct boundaries between individuals.
The frontal surface is perforated by many tiny pores that become more irregular
in shape as the colony ages due to secondary calcification. The orifice is
semicircular with 2 cardelles and a proximal V-shaped sinus. Avicularia are
elliptical and may be single or paired. They are raised on processes inferior
and lateral to the orifice, and generally have their mandibles pointed upward at
a 45-degree angle.
Synonymy:
None
Other Taxonomic Groupings:
Suborder: Ascophora
Potentially Misidentified Species:
S. cornuta is
easily confused with S. biaperta, and several other species.
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
The range of S. cornuta is somewhat
incompletely known due to the confusion of this species with other species.
However, it is likely to occur from Woods Hole, Massachusetts south to Florida,
the Gulf of Mexico and the Caribbean. In the Pacific, S. cornuta has
been reported along the North American coast. It is also known in the eastern
Atlantic along the West African coast.
IRL Distribution:
S. cornuta is
distributed within the Indian River Lagoon, but is more common at coastal
locations.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids measure approximately 0.35 X 0.25 mm in
size.
Abundance:
Though not among the most abundant of the
bryozoans, S. cornuta is encountered from April through December, and may
occur year-round. It is most abundant on beach rock and dead shells along the
coastlines near Walton Rocks and Seminole Shores from October through December.
Locomotion:
Sessile
Reproduction:
Reproduces along the Florida coast from October
through December. Colonies collected by Winston (1982) had the greatest number
of zooid ovicells filled with embryos.
Embryology:
Prominent ovicells are hyperstomial and globular.
Unlike other species of Schizoporella, they do not have pores over the
entire surface of the ovicell. Rather, there is a heavy outer rim of heavy
calcification, and a radially grooved central area. These grooves end in a row
of pores.
Embryos are brightly colored from orange-red to
cherry-red.
IV. PHYSICAL TOLERANCES
Temperature:
S. cornuta may
be present year-round at both coastal and IRL locations, and is thus considered
to be eurythermal.
Salinity:
In the IRL, S. cornuta is typically
collected from areas where salinity remains above 30‰. It is also collected
coastally.
V. COMMUNITY ECOLOGY
Trophic Mode:
S. cornuta,
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 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). S. cornuta was most commonly found
along the coastline on beach rocks and dead shells.
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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