Mammalia By: Marteyjah Beard

Evolution of Phylum Mammals are distinguished from all other classes of vertebrates by two fundamental characteristics - hair and mammary glands-and are marked by several other notable features: Hair-All mammals have hair. Even apparently naked whales and dolphins grow sensitive bristles on their snouts. The evolution of fur and the ability to regulate body temperature enabled mammals to invade colder climates that ectothermic reptiles could not inhabit, and the insulation fur provided may have ensured the survival of mammals when the dinosaurs perished. Mammary glands- All female mammals possess mammary glands that secrete milk. Newborn mammals, born without teeth, suckle this milk.

Shared Characteristics Are vertebrates (which means they have a backbone or spine). Are endothermic. Also known as “warm-blooded,” endothermic animals regulate their own body temperate which allows them to live in almost every climate on Earth. Have hair on their bodies. Produce milk to feed their babies. This allows them to spend more time with their young and teach them important skills they need to survive on their own.

Unique characteristics and adaptations Diphyodonty is a pattern of tooth replacement in animals in which the teeth are replaced only once throughout the lifetime. Mammals have a unique arrangement of three bones in the middle ear. These bones—the incus, malleus and stapes, commonly referred to as the hammer, anvil and stirrup—are unique to mammals, no other animal group has them. Teeth are specialized for cutting, shearing or grinding; thick enamel helps prevent teeth from wearing out. Mammals are capable of rapid locomotion. Brain sizes are larger per pound of body weight than most other animals'.

Regulate themselves The skin of the mammals is very important in regulating the temperature. Absorb nutrients Nutrients that the body can use are absorbed into the cells lining the small intestine. The rest of the material that cannot be further digested or used passes onto the large intestine. How they Reproduce All mammals reproduce sexually—sperm from the male fertilizes the female’s egg. How they defend themselves from injury They bite. Or They make threatening movements and noises. Or they use they claws if they have any. How they defend themselves from illness An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens.

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