Caribbean Sea
bnsullivan | August 31, 2009
Scleractinian corals, also known as stony corals -- or just hard corals -- are the primary reef builders in the oceans. Their polyps secrete calcium carbonate to form a skeleton. A minority of species live as single polyps, but most stony coral species are colonial, and the structures they build 'grow' over time. They form a myriad of shapes: mounds, branches, fingers, plates, and encrustations.
In several previous posts I discussed and displayed photos of a number of so-called soft corals, all of which are octocorals, i.e., their polyps have eight tentacles. Stony corals are…
bnsullivan | August 21, 2009
Sea fans are among the most beautiful sights seen by divers. Gorgonian sea fans are Cnidarians that build colonies in branching formations that usually are fan-shaped, thus the common name.
Like the Nephtheid soft corals I wrote about recently here on Photo Synthesis, Gorgonians are octocorals: each polyp has eight pinnate tentacles which it uses to capture nutrients suspended in the water column. They are seen most often on reef crests, or jutting out from drop-offs or steep banks in locations where natural currents will sweep plankton and other organic nutrients across the polyps'…