AMPHIBIOUS FISHES.

Star (Christchurch), Issue 6131, 18 March 1898, Page 2

AMPHIBIOUS FISHES.

[By C. F. Holder.] (Scienfi/io American.) Recently, in collecting below the high tide mark on one of the Pacific coast islands, the -writer found beneath almoßt every stone overturned a little fish, literally out of water and in no way inconvenienced by the lack of its native element. In the majority of instances the fishes were clinging to a stone by a singular s acker formed by the anal fins. They had been left by the retreating water, but had apparently preferred the ohange, and were now for Beyeral hours breathing air dire#ly instead of taking it rrom the water" tffe* the manner- of fishes in general. This peculiar habit has been observed in the European blennjf ( BmmH photisj. ft specimens kepU* ** aquarium iit was found that they became TeivlS^ when the tide WftM out. The observer* now placed a stone 11X the water, and the little fish at onoe crawled upon it and rested there, after thd manner oi a frog, for over an hour, then returning to ite native element. Such fishes are almost as truly amphibious as the frogs and other animals which appear to be equally at home on land or in the water. The case of the btetffcy. would seem to be remark* able, buff Cbere are a number of fishes which tfft'not only able to breathe out of water, but . HABITUALLY SEEK THEIE FOOD ON LAND. The most interesting examples are found among the Gobies of the tropics. The head in this fish is large, the eyes con- | spicuous and protruding, the pectoral finß powerful, resembling legs more than fins, and capable of lifting the fish and enabling it to jump along the sands or muddy shores of certain tropical islands. Two • genera are known, Periophthalmns and Boleophthalmus, both equally remarkable for their amphibious habits. They are particularly fond of a shelless mollusc known as Onchidium, which is often left stranded on the shore, to obtain which the fishes crawl out upon the muddy flats and hop along like frogs. They are so active that it is difficult to catch, them. Colonel Nicolas Pike informed the writer that he secured his specimens by shooting them with a shot gun. This was at Mauritius, at Matuku Island. Professor Moseley, the naturalist of the Challenger expedition, found them in great numbers also at Ceylon. They were hopping about on the mud flats beneath the mangrove trees,- and -Professor Moseley states that when pursued they prepared to escape by taking to the land rather than, to the water. At each iump they would clear a | foot. He says : " I have chased one at Trincoinali Harbour, which skipped along before me until it reached a rook, where it sat on a ledge out of the water in the Bun, and waited till I came up, when it skipped along to another rock." The speoies at the Fijian Islands is P. Koelreuteri, and it is usually found sitting or resting upon the dry roots of the mangrove trees, PERFECTLY AT HOME OUT OP WATER. The first fish ever observed to leave thewater, by a European naturalißt> was the now famous climbing perch (Anabas). Daldorf in visiting India heard the story as told by natives, to the effect that thebe fishes left their native element and walked overland, using their fins as limbs, but did not believe it. One day a native came to his camp and offered to take him to a spot where the emigrating fishes could be seen. Following the man through the forest, they finally came to & pool, or s watrvp that . was rapidly drying up, and from the mud proceeded a line or procession of fißhes, making their way up througn the grasß by • • the aid of their fins, presentingareinarkable spectacle. The fishes were emigrating, overland ; the water of their pool had dried up, and they were deliberately marching away in search of a locality better suited to a water-loving community. Daldorf later saw these fishes climbing small palms, presumably in search of food, though regarding this there is much doubt. In certain parts of India this migratory habit of fishes is so well known that the natives anticipate and repair to the localities with baskets and capture them by hundreds. Mr E. A. Legard states that on the Singalese Eiver also this habit is so Well known that all the inclosures in which the Anabas are kept are provided with covers, TO PREVENT THE FISHES FROM CLIMBING; OUT. A little fish (Gohius soporator), common on the coast of Texas, is almost equally femftrkabl©. A' naturalist, in collecting specimens, placed them in a pail, but was astonished, upon returning, to find that the fishes had all crawled up the sides, and were slowly but surely making their way to the water, and were apparently not inconvenienced by the change of element. In Gambia the fish Protopterus has a similar habit. At the first suggestion of the dry season it begins to explore the mud in the bottom of the stream in which it is living, and there forms a burrow in which it spends the weeks and months with not a drop of water until the rainy \ season begins again and it is released. The natives of Kottiar repair every year to the dry. banks of the Vergel Eiver and dig out certain fishes by hundreds as they would potatoes. They perform the work with piok and shovel, the fish in its case being dropped heavily, breaking open, displaying the animal eight or ten inches in length, and often as lively as though tak«jn directly from the water. It is evident that these fishes, which can so ! READILY CHANGE THEIR METHOD OF LIFE, must in some way differ from their companions which find water an essential. An examination of the fishes shows that they have gills over which water flows, and by which air is taken and made to serve its peculiar purpose. In other words j they have true gills, but in Periophthalmus and Boleophthalinus the gill cavity is much larger than in many fishes, and the gills do not fill it, leaving a space which might be filled with air or water. •• In other fishes which habitually leave the water, as Anabas already referred to, the gill cavity reaches upward, the mucous membrane forming a complicated foliated labyrinthine structure, so that the gills really present more of a surface than those of ordinary fishes, which spend all their time in the water. This labyrinthine structure long ago attracted the attention of naturalists, and it was supposed to be a provision for the storage of water when the fish was travelling overland; but investigation does not carry out this idea, and it has been shown that the cavities never contain water and are in no sense reservoirs. The theory held to-day is that the complicated organs are so adapted that they permit the animal to breathe either in the water or directly from the atmosphere. In other words, the labyrinthine organs are lungs, formed, according to Semper, " by modification of a portion of the water-breathing gill-cavity ; the fishes that have them are, therefore, to be regarded as aniphibioiiß with quite as much reasou as toads and frogs, or even better, since they are capable of changing the nature of their respiration —of air, that is, or of water— at will and suddenly, without auy interruption ; nay, are actually accustomed so to change it." * _