CROATIAN UNDERSEA WORLD IV, yellow gorgonian

Yellow gorgonian (Eunicella cavolini) Yellow gorgonian (Eunicella cavolini), is a coral that belongs to the Gorgoniidae family, widely spread in the Mediterranean Sea. The multi-branches colony, up to 50 cm in height, consists of thousands of interconnected tiny polyps approximately 2 mm in length. The branches are short and about 3 mm thick. The colony grows in a single plane, always perpendicular to the direction of the sea current. This is the best position to filter sea water, from which polyps collect plankton and organic matter using their tentacles. The colonies inhabit vertical segments of the seabed, with their depth ranging from 15 to 120 metres. Yellow gorgonian is unisexual and reaches maturity at about 15 years of age. Polyps in male colonies liberate sperm into the water and the eggs are fertilised inside female polyps. The fertilised eggs are then released into the sea and they drift in the current for one to four weeks. When they settle on suitable surface at the end of their journey, they develop into a new colony with the growth rate of only 1 to 3 cm per year. It is believed that yellow gorgonian has a lifespan of more than 25 years. In the Mediterranean Sea, colonies inhabited by more than 180 individuals per square metre were recorded. Their density is smaller in Croatian part of the Adriatic Sea, reaching some 20 individuals per square metre. Today, the yellow gorgonian is a protected species in Croatia, nevertheless susceptible to detrimental human influence. It is often destroyed by fishing gear, especially nets. The underwater temperature anomalies as consequence of the global climate change represent the biggest threat to its survival.