Monotremes of Australia

An Egg-Laying Mammal

Like the platypus, the echidna is a monotreme. Monotremes are egg-laying mammals and the echidna and platypus are the only two remaining examples of the order. There are two species of echidna - the Tachyglossus (fast tongue) aculeatus (prickled) or short-beaked echidna and the long-beaked echidna. Because of its liking for ants, the echidna is often referred to as the 'spiny anteater'.

The Echidna - A Monotreme(52289)

Monotremes are a primitive form of mammal. They have a cloaca or single hole for both reproduction and the elimination of wastes. Like reptiles, they lay eggs, have legs which extend outwards from the body and have a lower body temperature than most mammals. However, the shells of the eggs are rubbery like a reptile's.

Range
The short-beaked echidna is found through much of temperate Australia and lowland New Guinea. The long-beaked echidna is restricted to the highlands of New Guinea. The short-beaked is the smaller of the two species. The short-beaked echidnas in Tasmania are larger than those on the mainland.

Habitat
Echidnas frequent rocks, hollow logs and holes among tree roots.

Description
Echidnas vary from 35 to 53 cm in length. Males weigh around 6 kgs and females 4.5 kgs.

The body is short and stocky and, apart from the face, underside and legs, covered with sharp, creamy coloured spines. The spines are bout 50mm long. Fur between the spines gives good insulation.

The colour of the echidna varies according to its location. In hotter regions, the animals are honey-coloured and the fur is not so thick. Further south, they become darker in colour and in Tasmania, the echidna is black.

The limbs are strong and short. The front feet are equipped with five flattened claws which are well suited for scratching and digging. The hind feet point backwards and are used to shift soil away when the animal is burrowing. Grooming is carried out with the aid of two of the claws on the back feet. The tail is short and stubby. There is no hair on the underside of the tail. The echidna hosts the Bradiopsylla echidnae flea. At 4mm long this is one of the world's largest fleas.

The elongated snout is stiff, long and hairless. At 7 to 8cm long, it is capable of breaking up logs and termite mounds. The mouth is at the end of the snout and on the underside. Like the platypus, sensors in the snout detect vibrations though this faculty is not as developed as it is in the platypus.

Also like the platypus, the echidna has a hollow spur on the back leg. However it is unable to inject venom into its rival as the platypus can.

Behaviour
Echidnas are solitary although their territories may overlap. During bad weather they may burrow under bushes or grass tussocks. When threatened, it will curl into a ball, presenting the sharp spines to its enemy. It may wedge itself between rocks or, if the soil is soft , it will burrow down into the dirt.

Echidna in protective mode

The echidna uses its sense of smell to locate others of its kind, and to detect danger and find food. Echidnas often rest during the heat of the day, foraging during the cooler periods of early morning and late afternoon.

Nutrition
Echidnas locate food by its sense of smell. It will trap its prey with its long, sticky tongue. Food is ground between the tongue and the base of the mouth. Echidnas are insectivorous and use their strong front paws to rip open termite nests or overturn rotting timber. The mucous-covered tongue darts back and forth trapping ants and transferring them to the mouth. Grubs, larvae and earthworms are also eaten. As there are no teeth, food is ground between the tongue and hard pads on the roof of the mouth.

Reproduction
The female develops a pouch during the breeding season and carries a single egg in it for about ten days. The baby is about the size of a jellybean and weighs as little as 380 milligrams. The baby stays in the pouch for around three months. As the spines start to develop, it continues to suckle from specialised pores inside the pouch. The young are not fully weaned until several months old. The life span is estimated at under ten years although some have lived to 16 in the wild.

Threats
As their main food is ants, habitat loss is not quite the issue it is for some wildlife. Eagles and Tasmanian devils account for some losses as do dogs and cars. Use thick gloves if you must handle them and try not to drop them as their snouts are often broken by being dropped. Pricks from the spines can become infected.

Other articles on Australian animals that you might enjoy:
The Emu - Characteristics
Embryonic Diapause - an Overview
The Kangaroo - An Overview
The Koala - An Australian Marsupial
The Platypus - A Monotreme

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