Class Mammalia Phylum Chordata Mammals Class Mammalia Phylum Chordata

General Characteristics 1. Hair or fur: a. keratinized derivative of the skin b. uniquely mammalian c. hair coat also called a pelage. kinds of hair: guard hairs ,function: protects the wooly hair wooly hairs function: insulation

Glands 2. sweat: evaporation of salt, urea and water. 1. sebaceous: secretes oil that lubricates and waterproofs the skin and hair. 2. sweat: evaporation of salt, urea and water. 3. scent: secrete pheromones which may be used for defense, species and sex recognition and territorial behavior. 4. mammary: secretes milk.

Teeth a. homodont: teeth are uniformly conical (reptiles) b. heterodont: teeth are specialized for different functions (mammals) 1. incisors: for gnawing and nipping 2. canines: catching, gripping and tearing 3. premolars: for shearing and slicing 4. molars (bicuspids and tricuspids): for grinding

Structure of Tooth enamel- hard outer covering 2. dentin- largest portion of the tooth 3. cement- covers part in the jaw 4. pulp- nerves, blood vessels, and connective tissue 5. crown- top of the tooth 6. Neck 7. root(s)

Tooth

Numbers of Teeth 8 incisors, 4 canines, 8 premolars, 8 molars, 4 wisdom teeth (molars) mammals without teeth: whalebone whales, monotremes and anteaters

Development 1. Monotremes: oviparous (egg laying). 2. Marsupials: young develop in a pouch, young are nourished by “uterine milk”. 3. Placentals: young are nourished by the mother’s blood through a placenta. a. altricial- born without hair b. precocial- born with hair

Internal Anatomy seven neck vertebrae Skeleton seven neck vertebrae b. two occipital condyles (synapsid skull) c. trunk divided into thoracic and lumbar regions d. four limbs (except whales and dolphins) e. skeleton a combination of bone and cartilage

Respiratory and Circulatory Systems a.Lungs b. Diaphram Temperature regulation a. endothermic Circulatory 4-chambered heart b. systemic (whole body)and pulmonary loops (lungs)

Excretory System metanephric kidneys- produce urea b. Ureters c. urinary bladder d. urethra

Nervous System enlargement of the cerebral hemispheres b. enlargement of the cerebellum c. well developed sense of touch, associated with the hair follicles d. well developed senses of smell, sight, and hearing

Reproductive System internal fertilzation most are viviparous (live birth) No eggs! c. female mammals undergo an estrus cycle (cycle where the ova (egg)matures and is released) monoestrus: single yearly estrus cycle 2. diestrus: twice yearly estrus cycle 3. polyestrus: estrus cycles repeat often d. varied gestation period-length of time young develop within the female reproductive tract.

Lactation (only mammals have the ability to nurse young) a. two hormones control milk production estrogen is released by the pituitary gland during labor and causes milk production in alveoli. 2. progesterone is released by the pituitary gland during labor and causes milk production in laciferous ducts. b. nursing stimulates the pituitary which in turn continues to stimulate the release of both hormones