Photo copyright Tim Nicholson.
Taken on a night dive in the Egyptian Red Sea.
The body of this soft coral, Alcyonacea order, is stiffened with yellow spicules. Here the individual polyps are open, showing their 8 tentacles (the 8 tentacles help to confirm identification). A member of the Dendronephthya genus, it is partly down to these that much of the diving in the Red Sea is so beautiful. It has been discovered that soft corals produce a substance identical to a human sex-related hormone. Soft corals take in water to expand their body before feeding. This builds up a positive pressure inside the coral that supports the branches and trunk of the coral. A coral colony contracts by releasing the excess sea water from its system. When the branches contract their texture resembles that of a dried prune (Atiya).
The Red Sea in Egypt Part II, Invertebrates, by Farid S Atiya, Elias Modern Printing House, 1994, ISBN 977-00-6697-4