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Species Description:
Colonies generally form encrusting, flat plates 4- 12 inches across.
However, these corals can also be found as round domes. Coloration ranges
from whitish through gray and tan. Corallites are generally darker in
color.
Observations of Siderastrea radians along with 12 other stony corals
occurring at several sites throughout the Caribbean Sea indicated that each
represents a valid species. Siderastrea radians differed consistently
from Siderastrea siderea in coloration pattern, and corallite morphology.
Colony size and depth distributions also differed, further supporting the idea
that these corals are valid separate species. (Fenner 1993). Siderastrea
radians displays significant morphological variation. In disturbed habitats,
it was shown that larger colonies with spherical shape have a selective
advantage over other free living colonies (Lewis 1989).
Potentially Misidentified Species:
Can be confused with Massive Starlet Coral, Siderastrea
siderea.
II. HABITAT AND
DISTRIBUTION
Regional Occurrence:
Siderastrea radians occurs in
Florida, Bermuda, the Bahamas and the West Indies to South America.
IRL Distribution:
Siderastrea radians occurs in Indian River Lagoon inlet areas,
intracoastal waterway ledges, and the nearshore reefs of east central Florida.
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Colony diameter of Siderastrea radians sampled in
Cozumel, Mexico
ranged from 1 - to 9 cm in diameter, with a mean diameter of 2.9 cm
(Fenner1993).
Reproduction:
Siderastrea radians is a gonochoristic species that had a sex ratio
biased toward females when sampled at reef sites on the Atlantic coast of Panama
(Soong 1991).
Embryology:
Siderastrea radians is considered a brooder and spawns year round in
Panama. One flattened elliptical egg measuring approximately 0.7 x 0.3 mm was observed per ovary, with
28 ovaries per polyp. Planula larvae of S. radians, 0.8 mm in length when
fixed, were found year round, most often before full moon Soong 1991.
IV. PHYSICAL TOLERANCES
Temperature:
Recorded temperatures for Siderastrea radians colonies, on nearshore
reefs off Fort Pierce, Florida, ranged from 13 - 31 °C and averaged 24.6 °C.
Salinity:
Recorded salinity on nearshore reefs off Fort Pierce, Florida ranged from 26 -
36.4 ppt.
V. COMMUNITY ECOLOGY
Habitat:
Limestone pavement and ledges are preferred substrata for Siderastrea
radians.
VI. SPECIAL STATUS
Special Status:
Habitat Structure
Economic Importance:
None
Report by: J. Dineen,
Smithsonian Marine Station
with thanks to J. Reed, HBOI
Submit additional information, photos or comments to:
irl_webmaster@si.edu
Page last updated: July 25, 2001
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