Class - Mammalia
Mammalia is a small class of animals that are well known. There are about 4500 species of mammals. All mammals have similar characteristics. All mammals are endothermic, meaning they can maintain their body temperature. Mammals lack feathers, but are covered with fur or hairy skin. They usually all have specialized teeth. Mammal bones are solid and filled with either marrow or spongy bone. Mammals lack wings, with the exception of bats.
All female mammals have mammary glands, which produce milk for their young. The mammary gland is the defining feature of the class Mammalia, and is where the term Mammalian came from.
Mammary Glands: They secrete nutritious fluid, called milk, to their young. Male mammals have small inactive mammary glands. Milk is made up of water, protein, fat, and sugar.
Warm looded: All mammals are endotherms. Mammals require a lot of food; the food is broken down and uses the energy to keep their bodies warm. Most of the time mammals keep their body temperature constant; the only time it changes is when they are hibernating, estivating, or running a fever.
Staying Warm: Many use a thick coat (fur) to help insulate them. Some also use a thick layer of fat called blubber, this acts as insulation.
Teeth: They all have different shapes and sizes for different functions. Incisors are used for cutting into food, canines are use used to stab or grab and hold onto food, the molars are used to grind up the food. The different types of teeth reflect what type of diet mammals have.
Respiratory: All mammals need oxygen, they use lungs. They have a large muscle called a diaphragm that helps bring air into their lungs. All mammal have a four chambered heart, this allows blood with oxygen to be separated from blood without oxygen.