Page 69 - Atlas Of The World's Strangest Animals

DUCK-BILLED PLATYPUS 69

Comparisons

These wonderfully odd mammals belong to a group known as
monotremes. Unlike most mammals and marsupials, monotremes lay
eggs rather than give birth to live young. Membership of this elite
clique is limited to just two groups –the platypuses and the echidnas.
Although they share common ancestors, echidnas diverged from
platypuses 19–48 million years ago, when they returned to a Long-beaked echidna
completely land-based life.

Short-beaked echidna

Duck-billed platypus

are the echidnas, which are monotremes like the platypus. and feed them on milk from mammary glands, which is
Generally egg-laying is something that’s associated with where the word mammal originates. So, although
reptiles – although in this volume you’ll find exceptions to platypuses lay eggs, it’s the fact that the females feed them
that rule too! (See the entry for Jackson’s chameleon on on milk – produced by mammary glands – that makes
pages 26–29.) them a mammal
So if platypuses lay eggs but are still classified as Of course, because platypuses are intrinsically strange,
mammals, then what is it that makes a mammal a there is one slight difference to the usual set-up. Platypuses
mammal? Reptiles are usually described as being cold- don’t have teats, so when the youngsters want to feed, they
blooded ‘vertebrates’ (animals with backbones) whose tap their mother on the flanks, which stimulates her to
bodies are covered in scales or bony plates. Mammals are release milk through the pores in her skin.This milk
typically defined as warm-blooded, air-breathing collects in special grooves, ready to be lapped up by her
vertebrates. Mammals usually give birth to live young – hungry offspring.

This bill is covered in sensitive receptors,which pick up the These receptors are so accurate that the platypus can find
electric fields that are generated by muscle contractions. prey up to 10cm (3.9in) away.

(c) 2011 Marshall Cavendish. All Rights Reserved.