Juvenile about 5 mm long
Juvenile about 5 mm long
Juvenile about 5 mm long
Juvenile about 20 mm long
Juvenile about 20 mm long
Juvenile about 20 mm long. Note the bare branches of the fan coral where the anemone ate the polyps.
Base of a juvenile of 20 mm showing the radiating lines of the base, which is identical to that in adults. This photo Helene Clarke, all others above Guido Zsilavecz.
Adult about 200 mm long. Note the base from which the animal is hanging down from. Photo Andrew Taylor
On multi-coloured fan coral (Acabaria rubra) at Pie Rock the "things" shown in the top two photographs were seen. A mere 5 mm long at most, they looked superficially like some type of nudibranch. Looking at the photos they clearly were not, given that they lacked key features. What exactly they were was not clear, so on a subsequent dive at Castle Rock we searched on the same type of fan coral, and found more. First some further small ones were seen, but also some around 2 cm long. The bare "branches" of the fan coral were the first clue that this might be a sock anemone, given that they feed on corals. The stretching from one branch to another was the next clue, but it was the photo showing the base however that confirmed it: the radiating lines are the same as those seen on adult sock anemones. On the larger juveniles the appearance also stars resembling that of adults.
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.