The otherwise excellent if not quite true-to-life movie Finding Nemo perfectly illustrates the law of unintended consequences messages. Or at least the rule that the pester power of kids with no clue wins over the better sense of parents who should otherwise rule. So for a while, countless juvenile clownfish were condemned by their own celebrity and most probably made their final journey down a porcelain throne into a copper chute. The craze may be over, but clownfishes, also known as anemonefishes, are now irredeemably (is not exactly inappropriately) linked to a vision 20,000 leagues beneath the sea. Members of the feisty damselfish family (Pomacentridae), clownfishes are behaviourically distinct enough to warrant their own subfamily: Amphiprioninae. There are about 28 known species in the genus Amphiprion and they are found only in the tropical Indo-West Pacific.
To general surprise, clownfish are not overly uncommon (which is to say, they are neither abundant nor unremittingly rare) in Singapore waters. Even in the inter-tidal zone, the presence of suitable host anemone species is sufficient to suggest a probably sighting, unless predators or, more likely, poachers, had already made away with the inhabitants. In some places, the thieves go lock stock and barrel, carting off entire populations of anemones in pursuit of pleasure or profit. But this is still nothing compared to the wholesale destruction of habitats where ancient colonies of corals and generations of anemones and their commensal clownfish have at last no more cards to play and must dice with the dredge or head for deeper dives. Unfortunately, while larval clownfish can find their way to new reefs using olfactory cues, adult fish are (unlike their fictional counterparts) ill-suited for long distance travel, easily becoming sashimi when separated from the protective tentacles of their host.
Another far-fetched detour from fact to fiction was Marlin's avowed dedication to single parenthood. Fleshly clownfish prefer the pleasure of harems, with each colony comprising a dominant female and her entourage. Eggs are laid in the shelter of the anemone and the hatchlings disperse with the current to find their way home or colonise new reefs. Should the lady boss be devoured or lured away by amnesiac lesbian blue tangs, the largest of her former toyboys will start to lose his balls and take over the hive (this form of sequential hermophroditisim is known as protandry). As all clownfish are born male, it's probably true to say that the dream of every Nemo is to be a queen some day....
The species made famous by a foray to Sydney is Amphiprion percula, the Percula clownfish, which is restricted to the waters of Queensland and Melanesia. For some unfathomable reason, the similar-looking clownfish (pictured left) that ranges from Japan to Australia's northern coast is called the false clownfish (Amphiprion ocellaris). Besides biogeographical separation, differences in dorsal and pectoral ray counts separate the two species, although hybridisation facilitated by undiscerning or unscrupulous aquarists is not unheard of. A. ocellaris can be found in the anemones Stoichactis kenti, Stichodactyla gigantea, S.mertensii and Heteractis magnifica (see this site for a good review of commensal anemones). Local shores also harbour the tomato clownfish (A. frenatus), which is fruity red with a single white vertical stripe. This species prefers to live with Entacmaea quadricolor, the bubble or bulb-tentacle anemone.
The southern islands, including Sentosa until lately, still offer a refuge for large anemones and their associated clownfish. The reef flats that ring Pulau Hantu, for instance, are still robust and remote enough to elude casual collectors and near-shore dredging. Amidst a multicolour array of corals hard and soft, anemones find shelter and sustenance. Minute mysid shrimp dash about like Brownian particles and schools of generic small, silvery fish abound in the nutrient-rich waters. As the tide rises and recedes, the pelagics move in and out to feed, paying a toll of victims to the resident anemones and other sessile predators. Visitors hoping to capture their visage require glutes of steel to withstand the woes of waiting for shy Nemos who prefer to plunge themselves under a blanket of nematocysts than welcome lumbering guests. In the safety of their cnidarian condominiums, the clownfish cavort and claim the rewards of their specialisation and wager their lives on a future where reefs face no threat of reclamation...
The little nemos of Sentosa are probably now buried alive under a cascade of concrete, but you can still see sea anemones, clownfish and other gaudy reef creatures beyond the reach of waders by joining the Hantu Bloggers for their monthly dive.
Non-aquatic ducks can opt for the regular guided ReefWalks organised by the BlueWaterVolunteers at Kusu Island, or book a lengthier crawl through the seagrass beds of Pulau Semakau (with a free tour of pristine waste landfills) by the Raffles Museum of Biodiversity Research. Nemo sightings are not guaranteed (they might not be at home, or they might be in the homes of petty poachers) but new discoveries are sure to be made.
Plus, other places to explore that dispel the idea that there is nothing natural left worth preserving (click to download an article in Word format) in Singapore on the Wild Singapore site.
Further reading:
Daphne G. Fautin & Gerald R. Allen, A field guide to anemone fishes and their host sea anemones, ebook. Western Australian Museum, 1992.
Ohh the last time I went to Pulau Hantu, I saw batfish. Not much else. Thanks for the very educational bit on clownfish (I never knew they were born male, nor that the female dominates the harem!)
Posted by: Camemberu | 02 July 2007 at 06:49 PM
Shucks, your tomato clownfish shots were SUPER. Sigh... mine were really miserable :(
Posted by: Tide Chaser | 02 July 2007 at 10:37 PM