Presentation on theme: "Class: Mammalia. All mammals : Mammary glands Hair A middle ear with 3 bones A jaw that lets them chew food."— Presentation transcript:
All mammals : Mammary glands Hair A middle ear with 3 bones A jaw that lets them chew food
3 Main groups: 1.Monotremes – Mammals that lay eggs Example: Platypus 2. Marsupials – Give birth to immature, underdeveloped live young. Grow to maturity inside a pouch called the marsupium
Only marsupial in the USA Opossum babies in pouch
3. Eutherian mammals – Give live birth to live young that have completed fetal development.
Body temperature control: Endotherms Hair, subcutaneous fat (under the skin) help to conserve body fat. Many have sweat glands that help to cool the body during warm periods. Mammals without sweat glands will pant to get rid of excess heat. (Example of homeostasis)
Feeding: High metabolic rate – must eat about 10x the amount of food as a reptile of the same size to maintain homeostasis. Specialized teeth and jaws to eat different diets. Carnivore Herbivore Piercing, cutting, Tearing. Works like blades of scissors to crush and grind food Flattened for grinding tough plants Cutting, gnawing, grooming
Carnivores have a shorter digestive tract than herbivores. Cows have a rumen where food is stored and processed.
The teeth of whales have been replaced by stiffened plates called baleen. These strain out plankton from the water it takes in.
Respiration: Use lungs Circulation: 4 Chambered heart
Excretion: Well developed kidneys that extract nitrogenous wastes from the blood to form urine. Response: Most highly developed brain of any animals. Well developed sense of smell Ears – 3 small bones in the middle ear. Well developed eyes – many have color-sensing Structures in their eyes.
Movement: Many adaptations of limb bones and muscles to allow mammals to run, walk, climb, burrow, hop, pounce, swing, fly, leap, swim.
Reproduction: Internal fertilization Monotremes lay eggs outside the female’s body and nourishes that young with milk from mammary glands. Marsupials – give live birth to immature young, develop further in pouch and drink milk from mother. Eutherian mammals – have placenta. Get nutrients and oxygen from mother, give off wastes during development Have varied gestation periods (mouse = few weeks, Elephants = 22 months!) Parental care of young (varies among different species)