Diving Indonesia Periplus Adventure Guid. David Pickell
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within range, it is engulfed by the animal's formidable mouth.
Groupers. The groupers (family Serranidae), are a common family on Indonesian reefs, ranging in size from more than a meter to the tiny dottybacks or pseudochromids, colorful plank-tivores no larger than a man's little finger.
Most of the larger groupers are plainly marked, but some, most notably the bright red and blue-spotted coral grouper (Cephalopholis miniata) and the flagtail grouper (C. urodeta) dire exceptions. One of the largest fish on the reef is the giant grouper (Ephinephelus lanceolatus), which can reach 2 meters and weigh 400 kilos.
The fairy basselets or anthias (subfamily Anthiinae) are also groupers. Anthias, which hover in large schools around coral heads and soft coral colonies, picking plankton from the water, are very beautiful, and staples of underwater photography. Their names—the peach fairy basslet (Pseudanthias diaspar), the purple queen (P. pascalus and P. tuka) and the square spot anthias (P. pleurotaenia)—hint at their lovely colors.
Anthias are protogynous hermaphrodites, meaning that the fish all mature as females, and then a few undergo a terminal sex-change to male. These terminal males exhibit distinct, and very striking colors.
The dottybacks (Pseudochromidae), also among the real jewels of the reef, are small, secretive fishes that hide in caves and under ledges.
Another unique member of the grouper family is the comet (Calloplesiops altivelis). This small fish has long, black fins covered with a multitude of white spots. Because of the ocelli on the fins, and the fish's movements, it is thought to be a Batesian mimic of the juvenile spotted moray eel (Gymnothorax meleagris). A Batesian mimic uses its resemblence to a known dangerous animal to discourage predation.
Ciguatera Poisoning
Ciguatera is a toxin produced by a tiny dinoflagellate alga, Gambierdiscus toxicus. The alga itself is harmless enough, living around rocks, sea-grass and filamentatious algae. The quantities of poison in each organism are minute.
But the dinoflagellates are eaten along with the algae in which they live by herbivorous fish and invertebrates. These herbivores are then eaten by larger, carnivorous fishes, and these are in turn are eaten by even larger, and more voracious predators. Since the ciguatera is not broken down, it concentrates in the tissues of these higher order predators.
A human being who eats a ciguatoxicfishwill experience numbness in hands and feet, disorientation, weakness, vomiting, diarrhea, shortness of breath and even cardiac arrest. The poison is very serious. People have died from ciguatera and there is no available cure.
The greatest danger comes from fish at the highest levels of the food chain: snappers, groupers, large jacks, barracuda, some trigger-fish and moray eels. For reasons not well understood, certain species are morefrequentlyciguatoxic than others: particularly the red snapper (Lutjanus bohar), and also the giant moray (Gymnothorax javanicus), the saddleback grouper (Plectropomus laevis) and the giant grouper (Epinephelus lanceolatus).
Open-water fish (tuna, mackerel, etc.) are not part of the same food chain and are not affected, but any large, predatory reef fish is a candidate.
— David Pickell
Hawkfish. Hawkfishes (family Cirrhitidae) get their name from their predatory habits. These small fish (6-10 cm.) perch on coral heads or sponges—anything that gives them a good lookout—and when a small crustacean or fish comes within range, they swoop down on it like a hawk. Because they are so sedentary, they make very easy photo subjects. Some species are also quite colorful— particularly the large Forster's hawkfish (Paracirrhites forsteri)— and the long-nosed hawkfish (Oxycirrhitus typus) has an interesting, pointed "beak."
Jacks. The jacks or trevallies (family Carangidae) are often seen patrolling the upper reef slope in small groups. They are among the most active predators on the reef. Jacks are always on the lookout for a meal, and groups regularly interrupt their steady cruising with powerful bursts of speed as they chase unwary smaller reef fish. Sometimes a few jacks will make a sortie into a lagoon in search of prey. If they find and attack a school of fish the sea surface erupts as the hunted fish desperately try to escape, sometimes throwing themselves onto the beach in the attempt.
Snappers and sweetlips. Snappers (Lutjanus) are common predatory fish around deeper reefs, and are an important food fish. The red snapper (Lutjanus bohar), although delicious, is in some areas one of the most frequently ciguatoxic fishes (see "Ciguatera Poisoning," at left.)
Perhaps the most commonly seen reef fish in Indonesia is the yellow-backed fusilier (Caesio teres), a streamlined, 20-30 centimeter fish marked with bright blue and yellow. These planktivores, related to snappers, travel in large aggregations that provide a measure of protection against predators such as jacks.
Sweetlips (Plectorhinchus) are medium-sized, strikingly marked fish related to the snappers. They are common in Indonesia, where they can often be seen in mixed schools. The juveniles are especially attractive, with bold stripes and dots of white against a brown or black background.
Batfishes. The batfishes (Platax) are common inhabitants of Indonesian reefs, As adults, these animals take the shape of a large, silvery platter, as much as half a meter in length, with two or three broad black vertical bands. Traveling about the reef in small groups, they have a reputation for being very "intelligent," and seem to regard divers with curiosity.
There are three species commonly seen in Indonesia, the orbiculate (Platax orbicularis), the round-faced (P. Hera) and the pinnate (P. pinnatus). As adults, orbiculate and round-faced bat-fish are almost impossible to distinguish. The pinnate batfish can be recognized by its long snout.
As juveniles, the fish are very different in shape, with greatly elongated dorsal and ventral fins. Juvenile orbiculate batfish are mottled brown and have a transparent tail, which—together with their habit of floating on their sides in the shallows—allows them to match a dead leaf. Juvenile round-faced batfish are black and white and have long fins.
The most beautiful as a juvenile is P. pinnatus, which has a band of electric orange all around its body and fins. This juvenile, sometimes called the orange-rimmed batfish, is thought to mimic a toxic flatworm.
Butterflyfishes. The butterflyfishes (family Chaetodontidae) are beautiful, delicate looking fish that feed on small benthic animals. Some species feed heavily on coral polyps. They have laterally compressed bodies, and snouts and teeth adapted to their particular feeding habits, enabling them to pick up their preferred prey deftly. In particularly, the long-nosed butterflyfishes (Forcipiger) have long, thin mouths perfect for snatching small animals from cracks and crevices in the reef. These bright yellow fish will be seen hovering under overhangs in the reef, sometimes even upside down.
Some species, occur singly or in pairs, e.g. Forcipiger. Others are schooling fish. The black, white, and yellow pyramid butterfly fish (Hemitaurichthys polylepsis), for example, occurs in massive aggregations along the walls in Manado and other parts of eastern Indonesia, Common schooling butterflyfish include the bannerfish (Heniochus), the most distinctive of which is the pennant bannerfish (Heniochus diphreutes), which has a very elongated dorsal fin and bright yellow, white and black markings,
Angelfish. The angelfishes (family Pomacanthidae) probably make it onto more postcards than any fish other than the Moorish idol. They browse the reef for sponges, algae and occasional small crustaceans. Adult angelfish, some of which can reach 30 centimeters, are truly magnificent animals.
The twinspot lionfish, Dendrochirus biocellatus, is one of the most attractive of the dwarf lionfishes. It is much smaller than Pterois sp., growing to just 8 centimeters. Halmahera, Maluku.
In Indonesia, one can often see emperor angelfish (Pomacanthus imperator), with thin, horizontal stripes of blue and yellow; blue-girdled angelfish (P. [Euxiphipops] navarchus), with a deep blue "girdle" against bright orange; and regal angelfish (Pygoplites diacanthus), the most shy of the bunch, with vertical stripes of yellow, white and blue.
All Pomacanthus species have very