Photos by Pierre Niehaus	Colonial ascidians Ascidians, or sea squirts as they are more commonly known, are not as primitive as one might expect - in fact, they are highly evolved animals, closely related to the vertebrates! This is only evident, however, in larvae, as the adults are sessile, with two siphons (one for drawing water and nutrients in, one for expelling that water), and a sac-like body. This is very evident from the common red-bait, Pyura stolonifera. The animals shown on the left are all colonial ascidians, in that many individuals form a single colony. This hides their basic body structure, and it is easy to confuse them with sponges and other animals (including in one case, a nudibranch!) The range of shapes is tremendous - the ones shown here resemble some of those shown in the "Two Oceans" guide, but none is actually shown in that book (hence the lack of labels for the pictures!) For example, the colony in the third image resembles the blue choirboys Podoclavella sp., which is, obviously, blue (and all-over so), and has a yellow relative in the Eastern Cape. The red stalks of this one distinguish it from either of these two. Similarly, the bottom-most image is a red version of the blue one shown in Two Oceans, being a fan ascidian Sycozoa spp..
References: Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.
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