WEIGHT OF ANIMALS

Evening Star, Issue 20993, 6 January 1932, Page 12

WEIGHT OF ANIMALS

HEAVINESS AND HABIT Weight, as applied to living creatures, has an all-important influence upon their mode of life. Some of the heaviest animals are largo aquatic, for water at once removes weight and renders it compartaively negligible, says a writer in an English exchange. Thus certain species of whale can attain to 150 tons. The heaviest bird, considering its size, _ is the king penguinj which may weigh just over 401 b, or six times as much as an eagle of the same bulk. The reason for this is that water, through which the penguin literally flies, is vastly harder to displace than air, and to move through it, as does the penguin, _at some fifteen miles an hour, implies tremendous motive force. Apart from the mass of flesh and fat that goes to the penguin make-up, the bones are heavier and more solid than are those of any other bird. The breast muscles are likewise much more developed. A more lightly-built bird would find diving or sustained “flight” beneath the waves difficult, if not impossible. Except for the elephant—the largest terrestrial animal, attaining a weight of over four tons—all the Zoo’s champion heavy-weights_ are aquatic, or very largely so. The hippopotamus, for instance, in proportion to its size, is much heavier than the elephant. The giant squid weighs about three tons whilst the largest jellyfish turns the scale at Bcwt. It should be borne in mind, however that in the latter animal over 90 per cent, of its bulk consists of water. Marine crustaceans such as the giant spider crab of Japan weigh but 501 b, and the largest lobster seldom more than 151 b.

All insects are exceedingly light in proportion to their bulk. The giant of the race, a tropical stick insect, turns the scale at but a few ounces, and is a mere featherweight when compared with some earthworms, or even tapeworms, which may attain to nearly 2£lb. Minimum weight is essential to the life that so many insects lead, and, as a result, many of the terrestrial species of active habit are surprisingly light for their size. A total of 80,000 aver-age-sized fleas, for example, would be required to balance one ounce in the scale pan. Two hundred bees go to the ounce. This relatively great reduction in weight is one of the principal reasons why most insects do not drink in the accepted manner. The surface tension of a sheet of water is an inseparable barrier to most insects, and should one become wet whilst obtaining moisture it is faced with the handicap of lifting many times its own weight. Professor J. B. S. Haldane, writing on this theme, observes: “ An insect going for a drink is in as great danger as a man leaning out over a precipice in search of food. The average insect obtains its moisture by merely sipping it up from a damp or sodden surface.”

Weight is indeed a very mixed blessing. A mouse can fall down a mine shaft and suffer nothing worse than a severe shaking, whereas a man would bo killed outright. It is also the greatest hindrance in all matters appertaining to aero-dynamics, and sets a limit on the size to which such “ animal flying machines ” as cockchafers and mosquitoes can attain.

Weight, it will be seen, accounts for a groat deal, but not perhaps as regards that little-understood organ, the brain. The brains of most creatures known to science have been weighed, measured, and otherwise subjected to an exhaustive examination. Tho findings generally seem to prove that mental capacity, which makes or mars many activities, is not so much a matter of brain weight as of brain area.