Like the sedentary worms, and most of the mollusks the brachiopod starts life as a minute, free-swimming, wormlike larva, top-shaped and extremely active. During this period the mortality of the tiny unprotected creatures is very great, but once the mud-dwelling phase of existence has started, the race is secure from most enemies.
Feathers on Birds Adapt to the Seasons
There is a definite seasonal variation in the number of feathers on most birds. It amounts to a “natural adjustment in dress to the needs of the season”. This fact has been determined through the laborious process of actually counting the feathers of birds of the same species at different seasons.
The number of feathers declines steadily from early spring until the end of summer when the so-called “post-nuptial” moult takes place, after which the bird gets a new coat to last it a year. The bulk of the new feathers are acquired at the same time, but some are added progressively as the weather gets colder. An exception to this is found, however, among those birds which migrate south early. These apparently get a complete new outfit for their journey, since they will not be obliged to experience any noteworthy change of climate.
Why the Dodo Became Extinct
Smithsonian ornithologists have “rebuilt” a dodo. The dodo was a large, pigeon-like, flightless bird which was abundant on Mauritius and neighboring islands in the Indian ocean during the seventeenth century. It became a symbol—first of stupidity and later of extinction.
In its restricted environment it apparently had known no serious enemies prior to the coming of man. It had grown heavy, taken to a ground existence, and lost the ability to fly. It showed no fear of man and, because of its clumsy movements, was easy to catch and slaughter, but its flesh was tough and tasteless, even for sailors who had gone for months without fresh meat. Dutch navigators called it “the nauseating fowl”.
Dogs brought by the sailors killed great numbers of the stupid birds. They might have survived despite their slowness and stupidity, however, had it not been for the pigs and Ceylonese monkeys which came to Mauritius with the first settlers. The rooting swine destroyed the bird’s eggs and the monkeys devoured its young. It was entirely extinct at the start of the eighteenth century.
The Shark of the Soil
There is a protozoan, wormlike monster of the microscopic world, seen only about forty times in two centuries, which gobbles up its fellow one-celled creatures a hundred at a time, walks backwards and forwards at once, and hunts in packs.