Platypus-The mammal that lays eggs

 

Strange mammals that lay eggs

1.      Platypus

Platypus has little-tiny eyes, a flat head and silky-smooth looking short hair. It belongs to the great class of mammals, the furry or hairy animals. These  strange mammals that do not give birth to young, but lay eggs! All animals (or almost all) begin life the same way, as an egg-cell formed by the union of cells from two parents. This egg-cell may develop in the mother's body, nourished and protected by her, as in most mammals, or it may be made up into a package with all the food material it will need to develop and pass out of the mother's body as an egg. In this case it is hatched by the heat of the sun or kept warm by the mother. Some members of egg-laying classes, many sharks and some snakes, retain their eggs inside the mother's body until the young hatch and are born.

Of all the mammals living in this world today, only those of one order, the Monotremata (found in Australia, Tasmania and New Guinea), lay eggs. When this fact of egg-laying mammals was first reported, it was not believed by the scientists. So many strange tales turned out to be false that it is best to accept stories only after careful study of the evidence.

 

In 1884, however, a scientist named Caldwell went to Australia from England, especially to gather full and reliable information about the duckbill and echidna, or spiny ant eater, two types that belong in this strange order. He discovered beyond shadow of doubt that both really do lay eggs and after the eggs have hatched, the mother feeds her babies with milk, as other mammal mothers do.

 

Platypus is a delicate animal and very hard to keep in captivity out of its natural surroundings. However, a number of duckbills have been kept alive and watched carefully by many people.

 

These animals lay eggs and after the eggs hatch, nourish the young with milk. They are of two distinct kinds: the velvet-coated duckbill, or platypus; and the spiny an eater or echidna.

 

When the first stuffed specimens of the duckbill, or platypus, were brought to Europe they were thought to be frauds, like the "mermaids,"

Velvety fur like a mole: short, flattened tail like that of a beaver, all four feet webbed; a bill like a duck and no teeth – no wonder people found the duckbill hard to believe!

 

And when the collectors reported that the Australian men said this astonishing creature laid eggs like a lizard or turtle, that was going too far!

The scientific names the duck bill was given indicate how people felt-it was first called Platypus, or duck-like flat-foot," and then Ornithorhynchus paradoxus, which means puzzling bird-snout." And a curious puzzle he is.

 

Duckbills feed on snails, crayfish, earth-worms, water-living insects and insect larvae. Most of this food they capture by probing about in the mud at the bottom of the ponds in which they live. To assist in keeping the food caught under water, there are large cheek pouches, in which the prey may be stored. Duckbills can remain under water for six or seven minutes at a time.

Duckbills are found only in southern and eastern Australia and in Tasmania, where they live in the small rivers, streams and ponds. They cannot build dams as the beaver does, so they have to choose water that never goes dry. Even in places where they are common, duckbills are not often seen, for they come out of their burrows only rarely during the daylight hours. They are shy animals, especially the old males.

The duckbill is a thick, heavy-bodied mammal; the males reach more than twenty inches in length and may weigh nearly four pounds, while the females are several inches shorter and a pound lighter in weight. In color platypuses are deep, rich brown above, grayish or white below. The limbs are short. Unlike those of most mammals, the upper arm and thigh project  at right angles to the body, parallel to the ground, like the limbs of a reptile. The feet have broad webs which aid in swimming. The webs of the forefeet are especially large, extending far beyond the claws. Duck bills, at home in the water, swim very well indeed, but walk on land clumsily. Males have a long, sharp, horny spur on the heel; this spur is hollow and connects with poison glands in the leg. The duck like bill is covered with blackish, naked skin and, although the young platypus has several teeth, these are lost before the animal becomes adult. In their place are developed horny plates or ridges on the jaws and across the palate.  The eyes are small and bright, while the external ear is only a hole. No ear-shell, such as mammalian ears usually have, is developed in duck bills. If one is alarmed it makes a warning "splash-plunge" in the water and all other duckbills hearing the noise sink below the surface and swim to their burrows or to some distance from the threatened danger.

 

The home burrows are quite ambitious projects. A long tunnel is dug into the bank of a pond or stream from below the water level, sloping gently upward. This tunnel may extend for as much as fifty feet. It ends in a rounded chamber. Sometimes several tunnels are dug to other chambers,

and the entrance to one of the tunnels is usually on the bank above the water, hidden among bushes or by grass.

The duckbill is an expert digger, even though the webs on the forefeet project beyond the claws. There is a beautiful adaptation here, for the web folds back like a small umbrella into the palm, leaving the sharp claws exposed and ready for the work of digging.

The home of the platypus is a burrow dug far into the bank of a stream, from under the water. There is a very long, upward sloping tunnel, which leads to the "living-room." Here is a bed of moist leaves and the water plants, in which the mother lays her eggs. While the young are in this nest, their mother blocks the entrance with a ball of leaves and earth, so no other animal can enter. Even the father platypus does not enter the home during this period. When the babies are a little older, the ball is broken up and pushed aside, to leave the entrance clear. The duckbills, as they are also called, are very shy, and swim away, or to their burrows, at any warning of danger.

Fig. The burrow of Platypus

 

Despite their large quantity, little is known about the life cycle of the platypus in the wild, and few of them have been kept successfully in captivity. The sexes avoid each other except to mate, and they do not mate until they are at least four years old. Males often fight during the breeding season, inflicting wounds on each other with their sharp ankle spurs. Courtship and mating take place in the water from late winter through spring. Mating is a laborious affair; in one recorded session the male was seen tightly grasping the tail of the female with his bill as she led him on an exhaustive chase.

Duckbill eggs are about the size of sparrow eggs and have thin, flexible shells, like the skin on the inside of a hen’s egg, but tougher. The nest material is kept damp, which makes certain that the eggs will be kept moist, for otherwise they might easily dry up. Pregnancy is at least two weeks (possibly up to a month), and incubation of the eggs takes perhaps another 6 to 10 days. The eggs hatch after being incubated for a week to ten days. The young ones are very small at first, naked and with a short, fleshy beak. Baby duckbills do not for the first few days; then they begin e nourished by the mother's milk. There are no nipples, but the babies suck milk from the special mammary hairs and remain protected in the burrow, suckling for three to four months before becoming independent. Hatchlings, whose weight often increases by a factor of 20 during their first 14 weeks of life, possess vestigial teeth that are shed shortly after the young platypus leaves the burrow to feed on its own. Males take no part in rearing the young. Females construct specially built nursery burrows, where they usually lay two small leathery eggs.  The female incubates the eggs by curling around them with her tail touching her bill.