Monotremes

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Duck-billed platypus

Spiny anteater

The 3 classes of mammals differ strikingly in their modes of reproduction

Prototheria (monotremes) Metatheria (marsupials)

Eutheria (placentals)

Classification of mammals

Class Mammalia Subclass Prototheria

monotremes

Subclass Eutheria Infraclass Metatheria

marsupials Infraclass Eutheria

placentals

MonotremesMonotremes

PlatypusOrnithorhynchus anatinus

Short-beaked echidnaTachyglossus aculeatus

Australia’s most widespread mammal

Monotremes –

1) Lay eggs

2) Have a cloaca

3) No nipples

                         

Physical Description

Platypuses… are about the size of a household cat and weigh about 1 – 2

kilograms. are completely covered with thick, waterproof hair except for

their bills and webbed feet. have a sensitive, leathery blue-gray bill that can detect

electrical currents. have four legs with webbed feet to help them swim. do not have teeth, instead they have grinding plates to chew

food. have a wide, beaver-like tail that helps them swim.

Where Would You Find A Platypus?• The platypus is found in all freshwater

creeks, rivers, and lakes of eastern Australia.

• They like long, slow-flowing, shallow pools with solid angled banks that have plenty of plants and a good quantity of water-dwelling invertebrates to eat.

• The platypus is protected by law throughout Australia. Even though it is common in Australia, it is considered vulnerable and in decline.

• natural habitat being lost due to damming, drainage, and pollution.

• Decline noticed in areas close to Melbourne believed to be due to population growth.

Platypus Habitat

Australia

Status of the Platypus

•The platypus is officially classified as "Common but Vulnerable" in Australia. As a species, it is not currently considered to be endangered. •However, platypus populations are believed to have declined or disappeared in many catchments, particularly in urban and agricultural landscapes. In most cases, the specific underlying reasons for the reduction in numbers remain unknown.

The growth of cities, like Sydney (the capital of

Australia) could lead to the decline of the platypus.

Unusual Facts …

The platypus is the world's only venomous furred animal.  All platypuses are born with spurs on

their hind feet.  The spurs on the female fall off after the first year.  The spurs on males become venomous during the breeding season.

The female platypus lays eggs. When babies hatch, she secretes milk right through her skin to feed her young.

More Unusual Facts …

When European scientists first saw a platypus pelt, they thought it was a hoax! They didn’t think such an animal could exist! One scientist even took scissors to the pelt expecting to find stitches where the bill was attached to the rest of the body!

The platypus’ closest relatives are the two types of echidna (spiny anteater) that also live in Australia. They are the only three egg-laying mammals alive.

What I Think…

What other animal on this planet has traits of reptiles, birds, and mammals? Even though the platypus is not yet endangered, human encroachment is affecting its habitat.

Australia has taken steps to protect the platypus and hopefully ensure the existence of this creature in the future.

Predator and PreyPredator of: Prey of:Cray fish

Small frogsInsects worms

CrocodilesTasmanian devils Sharks

Some features of monotreme reproduction

• Ovaries larger (relative to body size) than with other mammals

• Oviducts open into common urogenital sinus, similar to a reptile’s cloaca (meaning of name “monotreme”)

• Milk is secreted by glands in skin and licked from tufts of fur in depressions where it concentrates near the mammary glands

• Testes are abdominal & the penis is a sac in the floor of the cloaca

• Young have an “egg tooth” like birds to help break out of the egg

• Platypus: 1 or 2 eggs

• Echidna: 1 egg

Typical platypus reproduction:•Platypus egg fertilization occurs within fallopian tubes before entry into the uterus. Eggs are eventually coated with a leathery, mineralized shell before being laid.

•Before getting its shell, the uterine wall produces nutritious secretions which the fertilized egg absorbs. The egg triples its size before getting a shell and being laid.

•Egg at fertilization = 4 mm, when laid = 12 mm.

•Egg retained in uterus about 28 days while development proceeds.

• THEN shell added & egg laid

• 10 more days of external incubation. (Eggs sticky, female cradles between stomach and tail.)

•Lactation about 3-4 months.

The eggsThe eggs

Platypus egg

Echidna eggs

Monotremes• Monotremes are the most primitive mammals. • There are only 3 species of monotreme: duck-billed platypus

and 2 echidnas. • Today, monotremes live only in Australia and New Guinea. • The name monotreme means “one-holed” in reference to the

cloaca, a single hole that is for the urinary tract, anus, and reproduction.

• Monotremes lay eggs that have a leathery shell. The young get their milk from a gland on the mother’s belly.

• The platypus lays her eggs on the bank of a stream, then curls around the eggs to protect them and keep them warm.

• Echidnas lay a single egg in a temporary protective pouch on the mother’s belly.

Duck-billed platypus

• After a platypus egg hatches, the baby (called a puggle), drinks its mother’s milk.

• They have a life span ranging from 10-17 years. • They live in burrows and spend much of their time in

freshwater ponds and streams.

Duck-billed platypus

• The platypus is a carnivore and uses its bill to strain tiny prey.

• It eats things like crayfish, worms, insects, snails, and shrimp from muddy water.

• It can also store food in cheek pouches while it is hunting underwater.

Sprawling, reptile-like Sprawling, reptile-like gait – BUT -gait – BUT -

Electrosensors in snout, detect movement of prey: Ants (echidna)Worms, insect larvae (platypus)

Short stout limbs:Heavy digging claws (echidna)

Webbed paddles (platypus)

Platypus Scientific Name

• Ornithorhynchus anatinus• “Bird-snout; Bird-like

Echidnas

• The echidna is also known as a spiny anteater. • Echidnas are solitary animals and live in burrows. • They have very tough spines that cover the top of the

body. • Echidnas can live over 50 years in captivity. • When attacked, the echidna will quickly burrow into the

ground or curl up into a ball.

Echidna (Spiny Anteater)Tachyglossus aculeatus

• "Echidna" derives from the Latin word for "viper”– Tongue protrudes like a snake

• Nocturnal • Terrestrial burrowers• Females normally have one

egg at a time

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Echidnas:•A single egg is laid in a pouch that sticks to the mother’s belly.

•Hatching occurs after the egg has incubated for 10 days.

•Baby echidnas are born blind and hairless.

•Young suckle in the pouch for about 55 days which is when they start getting too prickly! Lactation goes for several more months.

Only three living Only three living monotremes:monotremes:

Long-beaked echidna (genus Zaglossus)

Three monotreme species confined to Australia & New Guinea Highlands

Echidna

• Echidna spines are very long. • They also have long, sharp claws on the feet and a very

sensitive snout. • There are 2 types of echidna: long nosed and short

nosed. • Most echidnas are 14-39 inches long and have a tail that is

about 4 inches long.

Echidna

• Echidnas are insectivores. • They use their long, sticky tongue to catch ants,

termites, other insects, and earthworms.

Echidna’s Scientific Name• Tachyglossus aculeatus