Museum Notes GIANT IGUANAS

Southland Times, Issue 24056, 21 February 1940, Page 4

Museum Notes GIANT IGUANAS

Survivors Of A Lost World. LIMITED DISTRIBUTION The largest lizards in the world are the monitors, with the great dragons of komodo at the head of their family.’ There are, however, no monitors in the New World and their place there is, to a great extent, taken by the iguanas, a family essentially American, since, of all the numerous species composing it only two or three are found in the Old World, in Fiji, and, curiously enough, in a spot so far from America as Madagascar. The family, being large, is very varied and it includes many extremes: species which show the utmost beauty of colouring and. grace of form contrast with those which emphasize the drab and the grotesque; some of the smallest lizard forms and some of the largest. ■ . , The impressiveness of the larger iguanas does not, however, depend entirely on mere weight and measurement but on something more subtle; it is, perhaps, their general appearance and the way in which they recall all that one has imagined of the great and terrible reptiles of the remote past—the "dragons’" of the primeval world. They are, in fact, more dragon-like in form than the monitors and in this respect three or four species stand out from the others. Unlike the monitors which are carnivorous, the larger iguanas have chosen the most undragonly diet of leaves and fruit, though some of them are not averse to varying it at times with any odd insects, eggs, or small animals that may come their way. In the Galapagos Islands, where the youth of the world seems to have lingered and the dominant animal forms are reptilian, is the home of the first of these iguanas, one of the most remarkable of living lizards. It has the distinction of being the largest member of its family and the largest of American lizards. It has. moreover, a more outstanding character, for it is, so far as is known, the only lizard in the world which has taken to the sea for its living, and spends much of its life and finds all its food there. It is therefore most aptly called the marine iguana. DARWIN’S DESCRIPTION It was Darwin who, in “A Naturalist’s Voyage Round the World,” first described at length the appearance and habits of the sea iguana, and recently Dr William Beebe, Director of the New York Zoological Society’s Tropical Research Department, has added to the earlier information not only very much vivid and picturesque detail but also a wonderful series of photographs of this 'lizard at home. The marine iguana attains a length of upwards of four feet. Mere length is, however, no criterion of a lizards size; for example, the tuberculatea iguana grows to six feet long, though more than two-thirds of that is tail, and it is slender and not to be compared in bulk with its marine relation which is of heavy and massive build. As might be expected in a lizard which spends much time in the water, the tail is flattened sideways for swimming and the lizards swim with ease and speed by the movement of the tail, after the manner of an eel. The seaweeds which they eat grow in fairly deep water and although, when they can do so, the iguanas get as much of their food as possible when the tide is low, they must often have to go beneath the surface to feed. It is to be expected, therefore, that this lizard can remain under tvater for a fairly long period without coming up for air, but its capacity in that matter rather exceeds expectation. Darwin mentions that one of the seamen of the “Beagle” wishing to kill one of these lizards that he had captured, and thinking drowning the readiest method, tied a heavy weight to it and sank it in deep water. He let it remain there for an hour, but when at the end of that time he pulled it up the lizard was as lively as ever, a toleration of submergence which one exposed to the risks of the sea might well envy. SHORE LIFE It is when it is ashore that the marine iguana is most impressive. “As black and rugged as the lava boulders themselves,” says Dr Beebe, “these splendid saurians crept about like great prehistoric monsters. No other living inhabitant of these islands seemed so thoroughly a part of its environment. In colour, in rough contour, in the scales of its head standing up like volcanic cones, in its intimacy with lava and surf, it seemed an organic embodiment of the shores of these desolate islands.” It lies ashore sunning itself by day, and at night or when alarmed, takes refuse in crevices or holes in the rocks. If the hole should be too small to accommodate the entire lizard and a hold can be got on its tail, it may be pulled out, but only after a great struggle, for it not only clings to its refuge with its strong claws but also puffs out its body so that the rough scales help to grip the sides of the crevice. One might expect that when an iguana was so pulled out it would emerge in a particularly nasty temper, and that having such powerful jaws and claws it would use them with due effect. On the contrary, it is a most gentle and docile animal and cannot be induced, either by sudden fright or by prolonged teasing, to bite. While this marine iguana is still very numerous, Dr Beebe states that the vast hordes which might have been seen 25 years ago no longer exist, and he is of the opinon that they are slowly but certainly decreasing.