Mammals Coulter

Characteristics of mammals All mammal are endothermic vertebrates that have a four-chamber heart and skin covered with fur or hair. Most mammals are born alive, and every young mammal is fed with milk produced by organs in its mother’s body. The organ that produces milk is called a mammary gland.

Obtain food Most mammals have teeth. Teeth are adapted for chewing and breaking food into small pieces. Most mammals teeth in four different shapes. Incisors: flat-edged teeth used to bite off and cut food. Canines: pointed teeth that stab and tear into it. Premolars: flat upper surfaces; grinding and shredding food. Molars: flat upper surfaces; grinding and shredding food.

Obtaining oxygen All mammals breath with lungs. Mammals breath in and out because of the combined action of rib muscles and a large muscle called a diaphragm. Diaphragm is located at the bottom of the ribs. Mammals have a four-chamber heart and a two- loop circulatory system.

Keeping conditions stable Mammals are endothermic. They need energy in food to keep a steady internal temperature. Mammals have fur or hair to help keep internal conditions stable. In general, mammals that live in a colder climate have more fur than animals form a warmer environment. Mammals also have layers of fat beneath their skin. Fat is an insulator.

Movement Mammals have adaptations that allow them to move in more ways than members of any other groups of vertebrates. Most walk or run on four limbs. Some are adapted for swimming (dolphins), flying (bats), gliding (squirrels), swinging (orangutans), and hopping (kangaroos).

Nervous system Mammal’s nervous system coordinates its movement. The brains of animals enable mammals to learn, remember, and behave in complex ways. mammals senses are highly adapted and developed for each species to live.

Diversity of mammals There are three main groups of mammals: Monotremes Marsupials Placental The groups differ in how their young develop.

Montremes Egg-laying mammals There are only three species of montremes; two species of spiny anteaters and the duck-billed platypus.

Marsupials Are mammals whose young are born at an early stage of development, and they usually continue to develop in a pouch on their mother’s body. Gestation period, the length of time between fertilization and birth. Newborn marsupials are tiny. When they are born they are blind, hairless, and pink. They crawl along the wet fur of their mother’s belly until they reach her pouch. Once inside, they find one of her nipples and attach.

Placental mammals Placental mammal develops inside the mother’s body until its body system can function independently. Placenta is an organ in pregnant females that passes materials between the mother and the developing embryo. Most mammals, including humans, are placental mammals Placental mammals are classified into groups on the basis of characteristics such as how they eat and how their bodies move.

Caring for young Young mammals are usually quite helpless for a long time after being born. Many are born without fur. Their eyes are often sealed and may not open for weeks. Young mammals usually stay with their mother or both parents for an extended time. They learn important survival skills from their parents.

Review What characteristics do mammals share? What are the main groups of mammals? How do monotremes, marsupials, and placental mammals differ?