Monday, December 15, 2008

South Cottesloe Beach - Zoanthus praelongus

I was so excited when I spotted these coral polyp- or sea anemone-like creatures - but they are neither corals nor sea anemones. And this is the only colony that I could find on the South Cottesloe reef so far. But, well, I'm not really a very brave snorkeler and dare not venture too far from the shore.

The animal is possibly Zoanthus praelongus, a.k.a. sausage zoanthid (Wonders of Western Waters, Sue Morrison & Ann Storrie, 1999). The book mentions a related species in South Australia, probably Zoanthus robustus, which looks really similar to Z. praelongus (see Australian Marine Life, Graham Edgar, 2000).

The colony was about 2-3 feet across. (I know I'm really lousy in providing info about size, length, etc, I just couldn't be bothered to take a ruler with me or even measure with my forearm, or even my snorkel.)

Close-up shots are important because you really need them to id what you find. The water wasn't too deep - just about 2 m or so - and that was on a low tide morning. Zooming up my camera to 5X didn't quite do the job as the images simply got blurry - maybe due to the light conditions or that I couldn't stay still. And so, in order to get some close-up shots, I had no choice but to duck-dive.

If my blog gives you the impression that I'm a seasoned snorkeler and duck-diving is easy for me - I must clarify it's not true. Fortunately, after many attempts - to the point of getting breathless - I managed to get a few good close-up shots.

Anyway, I googled for Zoanthus praelongus. It seems that Zoanthus species in general gets its color from symbiotic algae (zooxanthellae) that live in its body. The microscopic algae carry out photosynthesis which is an additional source of food for the animal. But the animal also captures plankton and/or organic particulates drifting in the water for food.

Anyway, one other important piece of information I found is that Zoanthus species may produce palytoxin, which is said to be one of the most deadly marine toxins, fast-acting and fatal. I am still not sure if it's all or some species or whether Z. praelongus is one of them. Some websites advise against touching Zoanthus species with bare hands, especially when there is a cut or a wound.


Denis Wilson said...

Hi Chai
They are great shots, even if you had some difficulty capturing the images. I should say, especially good in the difficult circumstances.
As for the toxins, there are huge numbers of creatures which produce toxins, especially fungi. We tend to not take too much notice. Many plants which we use as cut flowers, even, are poisonous if eaten.

Tsun-Thai Chai said...

Hi Denis,

Thanks. I certainly felt that all my effort was worthwhile when I saw the photos.

I know many fungi produce toxins but didn't know that even some cut flowers are poisonous!

jreimer said...

hey Chai,

Sweet photos - would love to have a copy of any of them for my records.

As for PTX, Zoanthus should be safe but watch out for Palythoa spp. PTX is the real deal and scary!