form denticulata Smitt, 1872; Crisia
denticulata Osburn 1914
Other Taxonomic Groupings:
II. HABITAT AND
C. elongata is
a circumtropical species. In the western Atlantic, it occurs from Florida
through the Gulf of Mexico and the Caribbean.
C. elongata is
a common fouling organism collected year-round at coastal locations in Florida.
Winston (1982) found it to be a dominant species in the lower intertidal zone in
the vicinity of Ft. Pierce Inlet.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids of C. elongata measure an average of
0.07 X 0.60 mm. The lophophore averages 0.266 mm in diameter and bears 8
C. elongata may
be collected year-round at coastal locations from Sebastian Inlet to Seminole
Shores, however, it is most common from Winter through Spring. This species is
far less abundant in the summer months, but young colonies do occur. Winston
(1982) reported that polypides may not be functional in the summer. Zooids
collected in summer appear to be oversummering, having their peristomes extended, and openings occluded by diaphragms.
Colonies grow vegetatively throughout the Fall.
Gonozooids begin developing by December, and embryos are present in January and
Gonozooids are short and broadly inflated, with a
slight annulated surface. Oeciopore is a transverse slit located behind the
distal end of the gonozooid. Mature larvae are ovoid and ciliated, greenish
white in color and lacking pigment spots. Gonozooids with embryos and developing
larvae are yellow to brown in color.
IV. PHYSICAL TOLERANCES
The range of C. elongata is confined to the
warm waters of the tropics and subtropics. However, it occurs year-round in
Florida waters, and is thus able to withstand seasonal changes in water
C. elongata is
typically collected from areas where salinity exceeds 30 ‰.
V. COMMUNITY ECOLOGY
like all bryozoans, is a suspension feeder. Each individual zooid in a colony
has 8 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.
C. elongata feeds
almost passively, filtering particles as they pass along the tentacles. While
feeding, it rarely directs the lophophore, or flicks the outer ends of its
tentacles as has been observed in other species. Microscopic examination showed
that the laterofrontal cilia on the tentacles are quite long, and nearly fill
the spaces between adjacent tentacles when the lophophore is fully expanded. The
ciliation pattern on the lophophore forms an effective network that is able to
filter out most particles larger than 2 mm
(00007.87 inches). Additionally, the abundance of C. elongata among
colonies of sponges and tunicates may be indicative of the ability of this
species to take advantage of currents generated by other organisms.
Typical habitat for ectoprocts in the Indian River
Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters,
and man-made debris (Winston 1995). C. elongata attaches to the roots of
hydroids such as Thyroscyphus and Eudendrium in winter and early
spring. It also grows well on sponges.
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,
VI. SPECIAL STATUS
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
Report by: K. Hill,
Smithsonian Marine Station
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Page last updated: July 25, 2001