Living creatures on Earth need three basic things in order to survive: the ability to
eat, breath, and reproduce. All animals are able to do so. Animals are divided into species,
among these species are: Mammals, Reptiles, Arthropods, and Aves.
Mammals, also known as Mammalia, come from Latin meaning mamma breast. They
are called this due to the fact that Mammals are the only animals which have mammary
glands, which enable them to nourish their young solely on milk secreted from these glands.
Mammals are warm blooded, and all, except for marine mammals, are mostly or completely
covered with hair. Mammals give birth to live young, however, there are a few rare
exceptions to this rule. A few mammals, such as the platypus, lay eggs instead of having
live young. Yet once the eggs are hatched the females do have mammary glands, and
produce milk for their young. Another feature of mammals is that their heart has four
chambers and a muscular diaphragm that separates their chest and abdominal cavity. The
mammal class includes: Dogs, cats, horses, beavers, dolphins, bats and humans.
Another animal species are Reptiles, also known as Reptil which is Latin for Reptus,
meaning to crawl. Reptiles are usually hairless with dry, scaly skin. They are cold-blooded,
which means in order for them to maintain a stable body temperature, they must be
exposed to some heat source, such as the sun, or a rock warmed by the heat of the day.
Due to the need for warmth, Reptiles are naturally found in warm, dry climates. All
reptiles, except for snakes, have low slung bodies with long tails, balanced on four
awkwardly small limbs. Although there are a few aquatic Reptiles (Reptiles who live mainly
in water), they all must come up to the surface for oxygen. Reptiles do not give birth to
live young. Instead, they lay eggs on land. The female usually buries t
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