Mammals

1. Mammals

2. General Characteristics • Endothermic vertebrate with hair • Warm-blooded • Permits high level of activity at night and year-round (regardless of outside temperature) • Females have mammary glands • Function: make/secrete milk for young • About 5000 species • Ex: cats, dogs, humans, dolphins, elephants, kangaroo, whale, bat, rabbit, beaver, wolf, seal, mouse, platypus, chimpanzee, tiger

3. General Characteristics • High degree of parental care • Body covered by hair • In some, hair is reduced in size – like humans • All have an integument (external covering) • Contains: sweat, scent, sebaceous and mammary glands

4. General Characteristics • Breathe using lungs • Excrete using kidneys • Separate sexes • Young nourished by milk (made by the mammary glands) • Many have territories • These are areas from which individuals of the same species will reside • Will often resort to violence to protect these territories

5. classification • Rodents • Ex: mice, squirrels, rats, woodchucks • Have two razor sharp incisors for gnawing • Lagomorpha • Ex: rabbits, hares, pikas • All are herbivores • Hominids • Ex: humans, gorilla, orangutan, chimps • Insectivora • Ex: moles, shrews • Diet consists of insects

6. Classification • Carnivora • Ex: weasels, seals, walruses, dogs, wolves, cats, bears • Highly predatory animals, • Contain teeth for tearing flesh • Proboscidea • Ex: elephants • Largest of living land animals

7. Classification • Perissodactyla • Ex: horses, donkeys, zebras, rhinos • Often referred to as ungulates or the hoofed animals • Cetacea • Ex: dolphins, whales, porpoises • Limbs are modified into flippers • Live in aquatic environments only

8. Movement and response • Skeleton • Skeletal/bone make-up allows for: • High-speed running • Swimming • climbing trees • Movement of digits (fingers/toes) to help grasp objects • Joints allow for a greater range of motion

9. Movement and response • Hair: • Has become a modified sense “organ” • Purpose of hair: • Spines of porcupines—protection • Hair of most animals—insulation • Vibrissae (whiskers)—provide tactile sense • Slightest movement indicates minimal space available (cat/dog)

10. Movement and response • Moveable eyelids • Fleshy external ears • Well-developed brain • The largest brain in animal kingdom • Cerebrum—processes info for thinking and learning • High evolved brain allows for highly developed memory and capacity to learn topics/developmental milestones quicker

11. Movement and response • Highly elaborate sensory organs • Provide mammals with a high level of environmental awareness and responsiveness • Senses: taste, smell, hearing, sight • Most have great eyesight • Many can’t see color • Many will use echolocation to communicate and/or navigate • Ex: Bats, dolphins

12. Digestion and Eating • Teeth • Mammalian teeth are both more complicated and more efficient than in other vertebrates • Mammals are heterodonts (some of our teeth are different) • Specialized for variety of functions: • Includes: grind, stab, scissor, dig, chisel, sieve and lift (elephants tusks)

13. Digestion and Eating • Teeth, cont. • Teeth in mammals come in four different sorts: • Incisors, Canines, Premolars and Molars. • Not all mammals have all • Use this variety to eat a wide variety of food • Most placental mammals have between 20 and 40 teeth, while most marsupials have 30 to 50. • As a general rule animals that feed on insects have more teeth than either herbivores or the larger carnivores.

14. Digestion and Eating • Contain a secondary palate • Separates air passageway from the food passageway • Allows mammals to hold (and partially break down food) in mouths without interrupting breathing

15. Digestion and Eating • Have many feeding adaptations • Insectivores are often small • Herbivores have two groups • Groups: browsers and grazers • Have large molars adapted for grinding • Carnivores have large canines • Adapted for ripping/tearing meat • Other adaptations: • Ruminants (cattle, bison, goats) have a four-chambered stomach

16. Digestion and Eating • Energy and Wastes • Require much energy to keep a constant body temp • Produce a variety of waste products (uric acid, urine, feces, etc) • Digestive tract • If mammals eats only plants, longer digestive tract • Why? takes longer to digest plants/cellulose • If eat only meat, shorter digestive tract

17. respiration • Require a large amount of oxygen for respiration • 2 organ adaptations for this: • Diaphragm: • Muscle that contracts and therefore, allows for more rapid/controlled breathing • Four-chambered heart: • Separates blood into oxygen-rich/oxygen-poor

18. Life cycle • All have internal fertilization • All have mammary glands • 3 groups of Mammal life cycles: • Placental: • Marsupials: • Monotremes:

19. Life cycle • Placental: • Develop inside mother’s body • 95% of mammals are this • Placenta—organ which allows for nutrients, oxygen, carbon dioxide and wastes to be exchanged

20. Life cycle • Placental, cont.: • Gestation period—time that embryo stays in the mother’s body • Humans: 9 months, Elephants: 27 months, Mice: 21 days • Mammary gland—young continue to feed by suckling • Ex: humans, dolphin, elephant, most mammals

21. Life cycle • Marsupials: • Give birth to small, immature young that develop in a mother’s external sac (kangaroo) • Mothers can move around and look for food while baby develops in the pouch • Ex: kangaroo, koala, panda • Monotremes: • Mammals that give birth by laying eggs • Incubate using her heat • Ex: platypus