What are some adaptations of monotremes?

Answer 1

The two types of monotremes are platypuses and echidnas, and there are two species of echidna. Monotremes are egg-laying mammals, but like all mammals, they feed their young on mothers' milk.

The platypus has unique adaptations which enable it to live in a semi-aquatic environment. It has:

• Webbed feet with a retracting webbed membrane which can expose the claws, enabling the platypus to effectively dig burrows. Its claws are used for digging burrows into riverbanks for shelter, and the webbing membrane retracts for that purpose, but spreads between its toes when it needs to swim - which it needs to do to get its food.
• The platypus can remain underwater for between one and five minutes. Its bill has sensitive electroreceptors which pick up tiny nerve and electrical impulses generated by crustaceans and other animals that inhabit the bottom of the creek or river. The platypus then uses its bill to shovel away the dirt, and find the food. It does not have teeth, but hard bony plates which it uses to grind the food.
• The platypus lays eggs (as does the echidna), unlike other mammals. However, it secretes mothers' milk through glands, rather than teats, on which the young feed after hatching.
• The platypus is a semi-aquatic animal, with thick, waterproof fur.
• It has a flat, beaver-like tail which acts as a rudder
• 2 eye lids for protection
• Males have venomous spurs on their hind legs to harm or kill predators
• The liver gets rid of water but stores fat
• During mating season, the female platypus digs a separate chamber at the end of her burrow. The eggs are laid here, and once hatched, the mother "closes off" the chamber with a wall of leaves when she leaves, to protect the young. The wall of leaves is also designed in such a way that it helps remove excess water from the platypus when she returns, thus keeping the chamber as dry as possible.

Adaptations of the echidna include:

• A long tongue with sticky saliva, with which it eats termites and ants.
• A long snout which makes it easy for the echidna to burrow for ants, termites and worms.
• During breeding season, the female echidna develops a pouch, where she lays and incubates her egg. Although the pouch is little more than a fold of skin, it protects the egg from would-be predators such as goannas.
• The echidna has sharp claws for digging, and this ability to dig effectively is helped by its compact, muscular body shape and strong forelegs. When threatened, they can dig very, very quickly into the earth, disappearing horizontally, leaving only their quills exposed while they burrow.
• The echidna is very adaptable, living in a wide variety of climates and environments, from sub-alpine regions to arid semi-desert - wherever there are termites and ants.
• Echidnas burrow as a protective defence, leaving only the spines exposed to the potential predator.
• Echidnas are able to tolerate high levels of carbon dioxide, a necessity for an animal which burrows for protection (and sometimes for food). Because of this, they can also tolerate lower oxygen levels, and this is useful when bushfires occur.
• When flash floods occur, echidnas can dive underwater, and as they do so, their heart rate drops, which saves oxygen needed by the brain and the heart.