An animal is classed as a vertebrate when it has a backbone to provide support for the muscles and protection for the spinal cord. Vertebrates include fish, amphibians, reptiles, birds and mammals. The backbone is actually a series of small bones called vertebrate. They are joined together and locked with rope-like ligaments to provide a flexible but extremely strong anchor for the back muscles. The spinal cord runs down a channel inside the vertebrate, providing protection from damage. Some primitive fish, such as sharks and rays, have a spine made of a rough rubbery material called cartilage. There are approximately 45,000 living species of vertebrates. In size, they range from minute fishes to elephants and whales (of up to 100 tons), the largest animals ever to have existed. They are adapted to life underground, on the surface, and in the air.
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Fact File: The duck-billed platypus is a very unusual, small, semi aquatic mammal. It lives in lakes and streams of eastern Australia and Tasmania. It is notable in having abroad, flat, rubbery snout, webbed feet, and in that it lays eggs. |
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