platypus

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Platypus

Physical characteristics

Feeding

Burrows and breeding

Resources

The platypus is an egg laying mammal that is well adapted to the water. Physically, it looks like a mole or otter, with a beavers flattened tail and a ducks bill. It also has short, powerful legs and webbed feet. While the fur on its back is dense, bristly, and reddish or blackish brown, the fur on its underbelly is soft and gray. Its eyes are very small, and it does not have external ears. The platypus measures around 17.7 in (45 cm) in length, with its tail adding an additional 5.9 in (15 cm). Commonly referred to as the duck-billed platypus, it spends several hours each day in the creeks and rivers of eastern Australia and Tasmania. The rest of its time is spent in burrows, which it digs in the river banks.

The platypus is classified in the order Monotremata (meaning single hole), consisting of two families and three genera. The families are Tachyglossidae (the spiny anteaters or echidnas) and Ornithorhynchidae (the platypus). There is only one species of platypus, Ornithorhynchus anatinus, which is comprised of four subspecies. All three species in the order Monotremata are considered primitive, combining mammalian features with those of lower orders of vertebrates such as reptiles. For example, monotremes are the only egg-laying mammals. In other mammals, the young are conceived within the females body and are born alive. In monotremes, the eggs are fertilized internally, but are incubated and hatched outside the body. Monotremes, like all reptiles, also have a cloaca, a single opening through which feces, urine, and sperm or eggs pass. In other mammals, the cloaca is divided into an anus and genitourinary passages. Like other mammals, monotremes have fur, nurse their young with milk, and are warm-blooded.

Physical characteristics

The platypuss flat tail, duck-bill, short legs, and webbed feet are all characteristics enabling it to hunt in aquatic environments. However, since it spends most of its time on land, it has a few physical traits that can be modified depending on its particular location. For instance, on its webbed feet, the five individual digits end in claws. When the platypus is in the water, the skin of its webbed forefeet extends beyond these claws, so that it can better use its forefeet to paddle. On land, however, this skin folds back, revealing the claws, thus enabling the animal to dig.

The platypuss eyes and ears have similar modifications. Both are surrounded by deep folds of skin. Underwater, the platypus can use this skin to close its eyes and ears tightly; on land, it is able to see and hear quite well. Interestingly, the platypuss nostrils, which are located at the end of its bill, can only function when its head is above water as well. Thus, when the platypus is submerged with its eyes and ears covered and its nose inoperable it relies heavily on its sense of touch. Fortunately for the platypus, its leathery bill is very sensitive and, therefore, is its primary tool in locating prey while underwater.

Like all male members in the order Monotremata, the male platypus has spurs on each ankle connected to poison glands in its thighs. Rather than using these poisonous spurs to attack prey, the platypus only uses them against other platypuses or predators.

Feeding

The duck-billed platypus feeds on insect larvae, snails, worms, small fish, and crustaceans; it is most active at dawn and dusk. Typically, before feeding, the creature floats serenely on the surface of the water, resembling a log. When it decides to dive for food, it can do so quickly, with one swipe of its tail.

The platypus generally feeds near the bottom of freshwater creeks and rivers. It probes the muddy bottoms with its supersensitive bill to locate its prey. Until recently, it was thought that the platypus only located its prey by touch, but it now appears that the platypuss bill is also electroreceptive, allowing the animal to detect muscle activity in prey animals. Sometimes, the platypus stores small prey temporarily in its cheek pouches. Commonly, it stays submerged for about one minute, but, if threatened, it can stay underwater for up to five minutes.

Burrows and breeding

Platypuses construct two kinds of burrows in the banks of rivers and streams. A very simple burrow provides shelter for both males and females outside the breeding season, and is retained by males during the breeding season. At this time, the female constructs a deeper, more elaborate nesting burrow. Commonly, this burrow opens about 1 ft (0.3 m) above the water level and goes back into the bank as far as 59 ft (18 m). The female usually softens a portion of the nest with folded wet leaves. Whenever the female leaves young in her nesting burrow, she plugs the exit with soil.

The female usually lays two eggs, although sometimes she lays one or three. Typically, the eggs are about 0.7 in (1.7 cm) in diameter, are a bit rounder than most bird eggs, and are soft and compressible with a pliant shell. After she lays her eggs, the female curls around them, incubating them for seven to 10 days. During this time, she only leaves her nest to wet her fur and to defecate. Measuring about 1 in (2.5 cm) long, a newly hatched platypus is blind and nude. The female platypus has no nipples, therefore, she feeds her young on milk secreted through skin pores on her abdomen. The milk flows into two milk grooves on the abdomen and the young lap up the pools of milk. When the young platypus is about four months old, it leaves the burrow.

When the first platypus was sent to England, scientists thought it was a fake. Years passed before the existence of the animal was proven. Although platypus populations were formerly reduced by hunting for the fur trade, effective government conservation efforts have resulted in a successful comeback. Under the Australian Endangered Species Act of 1992 guidelines, today the platypus is neither on the endangered list nor officially on the list of vulnerable species. However, serious concern is raised because the platypus range closely follows densely populated regions of Australia where human activity greatly affects waterways. The species habitat may be disrupted by dams, irrigation projects, or pollution.

See also Spiny anteaters.

Resources

BOOKS

Augee, Michael L. Platypus and Echidnas. Mosman, Australia: The Royal Zoological Society of New South Wales, 1992.

Grant, Tom. The Platypus: A Unique Mammal. Sydney: University of New South Wales Press, 1995.

Moffat, Averil, ed. Handbook of Australian Animals. London: Bay Books, 1985.

Moyal, Ann. Platypus: The Extraordinary Story of How a Curous Creature Baffled the World. Washington, DC: Smithsonian Institution Press, 2001.

Nowak, Ronald M., ed. Walkers Mammals of the World. 6th ed. Baltimore: Johns Hopkins University Press, 1999.

Whitfield, Phillip, ed. Macmillan Illustrated Animal Encyclopedia. New York: Macmillan Publishing Company, 1984.

Kathryn Snavely

views updated

Platypus

The platypus is an egg laying mammal that is well adapted to the water . Physically, it looks like a mole or otter, with a beaver's flattened tail and a duck's bill. It also has short, powerful legs and webbed feet. While the fur on its back is dense, bristly, and reddish or blackish brown, the fur on its underbelly is soft and gray. Its eyes are very small, and it does not have external ears. The platypus measures around 17.7 in (45 cm) in length, with its tail adding an additional 5.9 in (15 cm). Commonly referred to as the duck-billed platypus, it spends several hours each day in the creeks and rivers of eastern Australia and Tasmania. The rest of its time is spent in burrows, which it digs in the river banks.

The platypus is classified in the order Monotremata (meaning single hole), consisting of two families and three genera; the families are Tachyglossidae (spiny anteater family) and Ornithorhynchidae (platypus family). There is only one species of platypus, Ornithorhynchus anatinus, which is comprised of four subspecies. All three species in the order Monotremata are considered primitive, combining mammalian features with those of lower orders of vertebrates such as reptiles . For example, monotremes are the only egg-laying mammals . In other mammals, the young are conceived within the female's body and are born alive. In monotremes, the eggs are fertilized internally, but are incubated and hatched outside the body. Monotremes, like all reptiles, also have a cloaca, a single opening through which feces, urine, and sperm or eggs pass. In other mammals, the cloaca is divided into an anus and genitourinary passages. Like other mammals, monotremes have fur, nurse their young with milk, and are warm-blooded.


Physical characteristics

The platypus' flat tail, duck-bill, short legs, and webbed feet are all characteristics enabling it to hunt in aquatic environments. However, since it spends most of its time on land, it has a few physical traits that can be modified depending on its particular location. For instance, on its webbed feet, the five individual digits end in claws. When the platypus is in the water, the skin of its webbed forefeet extends beyond these claws, so that it can better use its forefeet to paddle. On land, however, this skin folds back, revealing the claws, thus enabling the animal to dig.

The platypus' eyes and ears have similar modifications. Both are surrounded by deep folds of skin. Underwater, the platypus can use this skin to close its eyes and ears tightly; on land, it is able to see and hear quite well. Interestingly, the platypus' nostrils, which are located at the end of its bill, can only function when its head is above water as well. Thus, when the platypus is submerged with its eyes and ears covered and its nose inoperable it relies heavily on its sense of touch . Fortunately for the platypus, its leathery bill is very sensitive and, therefore, is its primary tool in locating prey while underwater.

Like all male members in the order Monotremata, the male platypus has spurs on each ankle connected to poison glands in its thighs. Rather than using these poisonous spurs to attack prey, the platypus only uses them against other platypus or predators.


Feeding

The duck-billed platypus feeds on insect larvae, snails , worms, small fish , and crustaceans; it is most active at dawn and dusk. Typically, before feeding, the creature floats serenely on the surface of the water, resembling a log. When it decides to dive for food, it can do so quickly, with one swipe of its tail.

The platypus generally feeds near the bottom of freshwater creeks and rivers. It probes the muddy bottoms with its supersensitive bill to locate its prey. Until recently, it was thought that the platypus only located its prey by touch, but it now appears that the platypus' bill is also electroreceptive, allowing the animal to detect muscle activity in prey animals. Sometimes, the platypus stores small prey temporarily in its cheek pouches. Commonly, it stays submerged for about one minute, but, if threatened, it can stay underwater for up to five minutes.


Burrows and breeding

Platypuses construct two kinds of burrows in the banks of rivers and streams. A very simple burrow provides shelter for both males and females outside the breeding season, and is retained by males during the breeding season. At this time, the female constructs a deeper, more elaborate nesting burrow. Commonly, this burrow opens about 1 ft (0.3 m) above the water level and goes back into the bank as far as 59 ft (18 m). The female usually softens a portion of the nest with folded wet leaves. Whenever the female leaves young in her nesting burrow, she plugs the exit with soil .

The female usually lays two eggs, although sometimes she lays one or three. Typically, the eggs are about 0.7 in (1.7 cm) in diameter, are a bit rounder than most bird eggs, and are soft and compressible with a pliant shell. After she lays her eggs, the female curls around them, incubating them for seven to 10 days. During this time, she only leaves her nest to wet her fur and to defecate. Measuring about 1 in (2.5 cm) long, a newly hatched platypus is blind and nude. The female platypus has no teats, therefore, she feeds her young on milk secreted through skin pores on her abdomen. The milk flows into two milk grooves on the abdomen and the young lap up the pools of milk. When the young platypus is about four months old, it leaves the burrow.

When the first platypus was sent to England, scientists thought it was a fake. Years passed before the existence of the animal was proven. Although platypus populations were formerly reduced by hunting for the fur trade, effective government conservation efforts have resulted in a successful comeback. Under the Australian Endangered Species Act of 1992 guidelines, today the platypus is neither on the endangered list nor officially on the list of vulnerable species. However, serious concern is raised because the platypus range closely follows densely populated regions of Australia where human activity greatly affects waterways. The species habitat may be disrupted by dams , irrigation projects, or pollution .

See also Spiny anteaters.

Resources

books

grzimek, h.c. bernard, ed. grzimek's animal life encyclopedia. new york: van nostrand reinhold company, 1995.

moffat, averil, ed. handbook of australian animals. london:bay books, 1985.

nowak, ronald m., ed. walker's mammals of the world. 5th ed. baltimore: johns hopkins university press, 1991.

whitfield, phillip, ed. macmillan illustrated animal encyclopedia. new york: macmillan publishing company, 1984.


Kathryn Snavely

views updated

plat·y·pus / ˈplatəpəs; -ˌpoŏs/ • n. (pl. platypuses ) a semiaquatic egg-laying mammal (Ornithorhynchus anatinus, family Ornithorhynchidae) that frequents lakes and streams in eastern Australia. It has a sensitive pliable bill shaped like that of a duck, webbed feet with venomous spurs, and dense fur. ORIGIN: late 18th cent.: modern Latin, from Greek platupous ‘flatfooted,’ from platus ‘flat’ + pous ‘foot.’

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platypusChiapas, tapas •campus, grampus, hippocampus, pampas •metacarpus, streptocarpus •trespass • Priapus • Lepus •Aristippus, Lysippus •Olympus • Oedipus • platypus •pompous •corpus, porpoise •Canopus, opus •lupus, upas •compass, encompass, rumpus •octopus •multipurpose, purpose

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platypus Monotreme mammal of Australia and Tasmania. It is amphibious, lays eggs and has webbed feet, a broad tail and a soft duck-like bill. The male has a poison spur on the hind foot. It is 60cm (24in) long and eats small invertebrates. Family Ornithorhynchidae; species Ornithorhynchus anatinus.

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platypus (Ornithorhynchus anatinus) See ORNITHORHYNCHIDAE.