Mammals Coulter Characteristics of mammals All mammal are

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 twoloop 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?