Friday, June 12, 2009

Grand Turk: Under the Sea

Two months may seem like a long time between two entries on the same day's activities, but I have to plead (now that I'm back in Canada) the pressure of actual work! Anyway, in my last post I mentioned that the real wealth of Grand Turk (at least as far as wildlife is concerned) lay not above the sea but under it. I'm hardly an underwater photographer, and my "equipment" consisted of a plastic disposable waterproof camera, but I thought that I should at least try to devote one entry to proving my point.

So, here are my wife Eileen and I waiting to go on our Grand Turk snorkeling trip. Whether it was "ultimate" or not I leave for you, dear reader, to decide, but it persuaded Eileen (who is no lover of the water) that she might just want to do it again sometime - a signal triumph, as far as I am concerned.

So it's off the western end of Grand Turk, over the reef and into the water...

...where we are greeted by a large, fierce-looking but quite inoffensive Great Barracuda (Sphyraena barracuda) and a school of what I think are young Grey Snappers (Lutjanus griseus), hanging around for a possible handout.

Caribbean reefs are (at least to my eye) quite different-looking from reefs in the Pacific -- more massively built, dominated by the spreading orange-rusty tines of elkhorn coral (Acropora palmata), so-called because of its resemblance to a giant stony set of moose antlers.

[Moose are called elk in Europe. We in North America call our own wapiti, a close relative of the European red deer, elk, just to keep everyone confused -- all of which has nothing to do with coral reefs, of course.]

Also massive, but entirely different in growth form, is brain coral (family Faviidae). This colony would appear to be grooved brain coral (Diploria labyrinthiformis). Notice the groove running down the middle of the ridges (the polyps grow in the "valleys" between the ridges, so I have no idea what the groves are for). If you want to know more about it, there's a nice writeup here.

The beauty of this particular patch of reef owed a lot to the soft corals, including these sea fans. The yellow one at the top is probably a Venus sea fan (Gorgonia flabellum), while the lovely purple specimen at the bottom is more likely a common sea fan (G. ventalina). I would have had to examine details of the stem structure to be sure, and I didn't. The bushy dark brown candelabras in the background are soft corals too, some sort of sea whip (but I have no idea which one).

Fishwatching on a coral reef is the underwater equivalent of birding, except that you can't use binoculars and the field guides tend to get soggy. However, photographing reef fishes with a plastic flashless disposable camera can be a bit trying, and I won't bore you with most of my hapless efforts. This supermale stoplight parrotfish (Sparisoma viride), however, makes for a good segue from my coral photographs, because parrotfishes eat coral. Notice the yellow "stoplights" on his tail.

The term "supermale" refers to the rather weird life history strategy of parrotfishes and at least some of their close cousins, the wrasses, in which females and, sometimes, young males can change into a new form, the supermale, differing in size, colour and often shape from its underlings. Supermales get to do most of the mating, and in some species take over "harems". If anything happens to the supermale, the dominant female in the harem turns into a supermale herself, and takes over.

Away from the coral, on the sandy bottom, we found a few southern stingrays (Dasyatis americana). With a few unfortunate exceptions (the late Steve Irwin, for one), there are very few cases of stingrays injuring swimmers; as long as you don't actually step on them, rays won't normally bother you (in fact, in some places in the Caribbean stingray-petting sessions have become major tourist attractions). It never hurts, though, to keep a respectful distance.

My one regret after our morning's snorkeling is that we only got a distant look at this little islet. It is apparently one of the homes of the Turks and Caicos Rock Iguana (Cyclura carinata carinata), a reare and eclining species confined to small islets fee of introduced mammals. There may be some 30,000 of them, but they are confined to a total land area of only 28 square kilometres, and a number of colonies have disappeared over the past few decades. They are a potent symbol of the islands (see here), and I would have loved to have seen one.