Monday, 21 November 2011

Mammals



Mammals are one of the 6 main classes of animals.  Animal classes are groups of animals that scientists consider to be alike in some important ways.  Mammals are the animal class that people belong to.  


There are only about 4,000 kinds of mammals.  This sounds like a lot, but when you consider there are 21,000 kinds of fish and a whopping 800,000 kinds of insects you’ll realize mammals are a pretty small class!

Here are some of the ways that mammals are alike!

Mammals are warm blooded.
but mammals’ bodies are built to maintain just about the same temperature all the time.  Warm blood lets the mammals be very active and live in a wide variety of places.  
Mammals are everywhere.  Polar bears live in very cold areas.  Camels live in hot areas.  Moles live under the ground.  Bats live in caves and fly in the air. Dolphins live in the oceans.  Fur and fat help protect mammals who live in the cold.  Mammals sweat or pant to release extra heat if they live somewhere toasty.


Mammal Babies:  We all drink Milk!
Most mammal babies live inside their mothers before they are born, just like humans.
When the baby is big enough, it comes out of its mother’s body.  Many people mistakenly think that being born alive is something all mammals have in common.  There are, however, a few mammals (like the duckbilled platypus) who lay eggs like a bird!


Mammals aren't spineless
Mammals are vertebrates, which means that they all have backbones (spines).  Believe it or not, most animals don't have backbones -- mammals are one of the few groups that do.  
All mammals, except some sea cows and sloths have seven bones in their necks.  This includes giraffes who have VERY long spines!  Their necks can be 6 1/2 feet long, but they're still made up of just seven bones.



Tetrapods
All mammals have four limbs. Some mammals walk on all four limbs, others walk on two and others can do both.


Hair
Mammals have hair which grows from follicles found in the skin. Functions of the hair include warmth, protection and to act as a sensor.


Respiration
Mammals breathe using a pair of lungs composed of spongy like material. The breathing rate of mammals varies - a whale might only breathe once every two hours while smaller rodents breathe 150+ times a minute.


Reproduction
Most mammals give birth to live young but a few lay eggs.
E.g. Platypus lay eggs.
Platypus lay eggs.


Cat gives birth.



Let us see what is mammals together!



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