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Rare fish of the coral seas
Deadly Stone-Fish. If you sit quietly beside a coral pool, or drift over a reef in a glass-bottomed boat, you may find yourself gazing in enchantment at a world , of fishes, diverse of form, bizarre of pattern and gaudy of color. No fish are move colorful. But in this region of extremes not all the fish are beautiful; for the Barrier Reef includes am ongst its fishes the inf am ous stone-fish which must be ranked as one of the ugliest in the world. It is also extremely venomous. Growing to a length of about a foot, the stone-fish, covered with warty tubercles, burrows in the sand and is easily mistaken for an eroded piece of coral. It rarely hunts its prey, but just squats and waits for it to come its way. -Along its back are thirteen spines which normally lie depressed; but the moment the fish is touched they stand up, erect and rigid, and woe betide any animal pricked by them. Each is provided with two venom glands, each is as sharp as a needle, and each is provided with grooves in its side which carry the venom into the punctured wound.
The stone-fish has been responsible for the death of human beings who may have handled it unaware of its poisonous spines, or who may have inadvertantly trodden on it; but casualties are very rare, and with heavy soles on one's shoes there is little real danger.
The Butterfly Cod. The butterfly cod, a close relative of the stone-fish, is as beautiful as the latter is ugly. There are few fish so well adorned; there are few fish so graceful in their movements. Its body 'is covered with vertical scarlet stripes of irregular width on a cre am y background; its great expansive dorsal and pectoral fins, richly decorated with similar stripes, open like fans, the individual rays having feather-like trailing edges; the tail and anal fin are beautifully spotted; while the huge ventral fins are a rich greenish-purple con spicuously splashed with white.
Mud-Skippers. We have already seen that some of the coral islands of the more northerly portion of the reef em-brace mud. flats that lie bare at low tide. If you approach one of these when the tide is out, you will probably see numbers of small fish basking in the sun or squatting on the sloping trunks or aerial roots of the mangroves. You have come across the renowned mud-skippers. Frighten them and they will skip over the surface of the mud with the agility of a lizard, to disappear into a nearby pool or down a crab's burrow. But don't expect to find them in the pool, for they quickly burrow in the soft, oozy mud, and further pursuit is hopeless.
Here is a fish that is fast becoming a land animal, and even at this stage of its evolution it will drown if kept permanently under water. How is it that this fish can live for so long out of water when other fishes would quickly. perish? The explanation lies in the enlarged cavity of the gill-covers which contain air as well as water. The surrounding tissue is able to absorb oxygen from the air and thus carry out the function of a primitive lung. But this curious fish also breathes in another way. It is frequently seen lying on the edge of a pool with its tail in the water. Now, the tail is very thin-walled, and oxygen dissolved in the water can pass through to reach the minute blood ves sels that are abundantly distributed just beneath the skin surface. In other words, the. wonderful mud-skipper can actually breathe through its tail.
The Sucker-Fish. Another commonish of the Barrier Reef is the sucker-fish, an inveterate hitch-hiker. Although quite an active swimmer, if a turtle or a large fish such as a shark comes its way, the sucker-fish attaches itself to it and is carried about the sea, feeding on the scraps that its bigger host overlooks. For sheer laziness this fish has no equal. It attaches itself by means of an oval disc situated on the top of its head. This disc: consists of a series of plates arranged as in a Venetian blind, all pointing backwards. When a sucker-fish se-cures itself to a larger animal, it de-presses the base of the disc and so creates a partial vacuum which forms an extremely powerful attachment. If the fish wishes to swim forwards it can free itself with ease, but if you attempt to remove it by pulling it from behind, great strength is required, and it is possible that the flesh of the fish will tear before it can be detached. Turtles up to forty pounds in weight have been lifted off the ground by gripping sucker-fish attached to them.
The Australian aborigines literally hunt turtles with sucker-fish. With a line woven from bark fibres and a hook made from bone or pearl shell they fish for sucker-fish. Having captured one, they tie a line securely round its tail and, sighting a turtle in the distance as it comes to the surface to breathe, they throw the sucker-fish overboard, splashing the water with their paddles to frighten the fish away from the canoe. As the fish swims away from the boat, the blacks pull the line taut every now and again to determine whether the fish has located the turtle; and as soon as a weight is felt they haul the line in vigorously in order to prevent the sucker-fish from detaching itself. As soon as the turtle approaches the canoe and comes to the surface to breathe, a harpoon is thrust deep into its shoulder and it is quickly hauled on board. Turtles up to a hundred pounds in weight have been captured by the aborigines in this way.
The Devil Ray. Occasionally, as you sail over the crystal-clear waters of the Great Barrier Reef , you may see two triangular fins breaking the surface simultaneously, and your first thoughts will be of sharks. The fins you have seen are the tips of the great pectoral fins or “wings” of a devil ray, which swims by an undulating movement of its pectoral fins, the extremities of which frequently break through the surface of the water in unison. Devil rays around the Barrier Reef may grow to a weight of upwards of a ton and, if harpooned, they may tow a boat over the sea for hours. In spite of their formidable appearance they are quite harmless, but the ancients had a great dread of them for they were convinced that they could wrap their fins round a man and quickly and easily squeeze him to death.
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