WEIGHT" OF ANIMALS

Evening Post, Volume CXIII, Issue 1, 2 January 1932, Page 18

WEIGHT" OF ANIMALS

Weight, as applied to living creatures, has an all-important influence upon their modo of life. Some of the heaviest animals are largely aquatic, for water at once removes weight and renders it comparatively 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 penguin, which may weigh just over 401b, or six times as much as an eagle of tho same bulk. The reason for this is that water, through which the penguin literally fljes, 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 thoso of any other bird. Tho 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 tho elephant—the largest terrestrial animal, attaining a weight of over four tons—all the Zoo's champion heavyweights are aquatic, or very largely so. The hippopotamus, for instance, in proportion to its size, is much heavier than the elephant.

Tho giant squid weighs about three tons, whilst tho largest jellyfish turns the scale at Scwt. It should be borne iv 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 501b, and the largest lobster seldom more than 151b:

All insects are exceedingly light in proportion to their bulk. The giant of tho race, a tropical stick insect, turns the scale at but a few ounces, and is a mere featherweight when compared

HEAVINESS AND HABIT

with some earthworms, or even tapeworms, which may attain to nearly 2ilb. 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 SO,OOO average-sized fleas, for example, would bo required to balance ono ounce in the scale pan. Two hundred bee,3 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. Tho average insect obtains its mositure by merely sipping it up from a damp or sodden surface."

Weight is indeed a very mixed blessing. A mouse can fall down a mineshaft and suffer nothing worse than a severe shaking, whereas a man would be killed outright. It is also tho greatest hindrance in ;;11 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 bo seen, accounts for a great deal, but not perhaps as regards that little-understood organ, the brain. Tlio brains of most creatures known to science have been weighed, measured, and otherwise subjected to au exhaustive examination. The findings generally seem to prove that montalßapacity, which makes or mars many activities, is not so much a matter of brain weight as of brain area.