Sock or walking anemone
Photo by Victor Barnard
Sock or walking anemone feeding on soft coral
Photo by Graham Heiberg
A juvenile
Another juvenile
Bottom two photos Guido Zsilavecz
Also called the walking anemone, this animal is a rather different type of anemone, and its description required not only a new species, but a new genus as well - there is simply nothing like it...
Anemones can move - they are not the completely sessile animals stuck to rocks one tends to think they are, but they don't move much at all. Anemones are pretty much opportunistic feeders, waiting for anything edible to float by, get trapped by their tentacles with stinging cells, before getting eaten. The sock anemone is different. It feeds on the multi-coloured sea fan Acabaria rubra or soft corals. The problem is, the sea fan or soft corals do not float about - they are sessile. So, once the anemone has decimated the polyps, in the case of the sea fan leaving only bare branches, it needs to move on. This it does by relaxing its already floppy body, allowing it to "wave" about in the surge until it manages to latch onto another sea fan or bunch of soft corals, after which it simply lets go at the other end, and re-settles to continue feeding.
Sock anemones are generally found in deepers waters further offshore (although at times it may be found inshore in waters less than 10m) and are moderately common at places like Coral Gardens, any of the Hout Bay Sentinel reefs, and the Smitswinkel Bay wrecks. Juveniles were pretty unknown until SURG discovered some unusual looking things on sea fans, which upon finding slightly larger ones showing the anemone's typical radially striped base, revealed what they were.
A new sea anemone from South Africa (Anthozoa, Ptychodactiaria), KW England and EA Robson, Ann. S. Afr. Mus. 94 (5) 1984
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.