Photo by Ros Morgenrood
Photo by Ros Morgenrood
Ros asks what species of nudibranch this is.
While it does superficially look like a nudibranch in overall shape, it is more likely to be a small colonial ascidian ("sea squirt" - relatives of red bait) rather than a nudibranch. If you look closely you will see that there are paired blue rings not only on the "back" but also on the sides of the lump. These look like the siphons of a lot of little translucent squirts all packed together in a jelly-like blob, which in this case accidentally looks a bit like a nudibranch.
In the second photo, taken from the edge of another of Ros' photos, a similar colony can be seen, which has the same colouration, but looks nothing at all like a nudibranch.
Identification of ascidians is not simple. There are 82 species listed and described in Annals of the SA Museum Vol 108 part 1, and this is condidered a minor and fairly random sampling of the South African ascidians. A few of these have photographs of colonies, but mostly there are only line drawings which are not useful if you dont have a specimen under the microscope. Colonies sometimes have a charcteristic shape or structure, but often are variable. Colour may be characteristic but is also often variable. What is left is largely the size of the zooids, and the pattern in which they cluster.
It was not possible to identify this specimen from the available descriptions and photographs. It may be useful to researchers to record times and places where unidentified ascidians are photographed, so they can be found again if necessary, and some idea of the range can be developed. If possible please include such information when contacting SURG.
South African Ascidians. Monniot, C. Monniot, F. Griffiths, C.L. and Schleyer M. 2001. Annals of the South African Museum Volume 108 Part 1.
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987.
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.