Characteristics of Mammals

1. Characteristics of Mammals

2. Major Characteristics • Endotherms: ability to maintain a fairly constant body temp. • Enables them to live in almost every place on Earth • Hair: made of keratin like feathers & scales • Insulation & waterproofing

3. Major Characteristics • Nurse their young • Gland = organ that secretes substances inside or outside the body • Mammary glands = secretes milk a liquid rich in fats, sugars, proteins, minerals, and vitamins. • Respiration & Circulation: • Diaphragm: sheet of muscle located beneath lungs; aids in breathing • 4-chambered heart • Lungs

4. Mammal teeth • Mammals teeth are differentiate for the type of food they eat • Types: • Incisors: chisel-like modified for gnawing • Canines: puncture & tear flesh • Premolars & molars: used for slicing or shearing, crushing, and grinding • Cud-chewing enables them to break down cellulose of plant cell walls into nutrients that they can use and absorb

5. Mammals can learn • Primates are perhaps the most intelligent animals. • The result of complex nervous system and highly developed brains • Outer layer of brain is folded forming ridges (gyrus) and grooves (sulcus) these increase surface area for brain’s activity

6. Diversity of Mammals • Placental Mammals: • Uterus: hollow, muscular organ in which offspring develop • Nourishment of young inside the uterus occurs through an organ called placenta; which develops during pregnancy • Gestation: time during which embryo develops inside uterus

7. Diversity of Mammals • Marsupial: mammal in which young have a short period of development within mother’s body, followed by second period of development inside a pouch made of skin & hair found on the outside of the mother’s body • Monotremes: mammal that reporduces by laying eggs • Platypus and anteater

8. Mammalian Orders • Order Rodentia: • largest mammalian order • Rodents are found everywhere in the world besides Antarctica • Includes: squirrels, chipmunks, gophers, mice, rats, & porcupines • Have 2 pairs of incisors that continuously grow as the rodent lives so it must continuously gnaw on something.

9. Order Edentata • Includes: anteaters, armadillos, & sloths • Name of the order means “toothless” but only anteaters are completely toothless

10. Order Lagomorpha • Includes: rabbits, hares, and pikas • These animals are found worldwide • Differ from rodents in that have double row of upper incisors, with 2 large front teeth backed by smaller ones. • Herbivores

11. Order Insectivora • Includes: shrews, moles, hedgehogs. • Found in North America, Africa, Europe, & Asia • Most have long pointed noses that enable them to probe in the soil for insects, worms, & other inverbebrates • Have stout limbs for digging, small eyes, and no external ears

12. Order Primates • Include: lemurs, tarsiers, and anthropoids (humans, monkeys, and apes) • Most primates are omnivores and have teeth suited for varied diet • Larger brains, two-forward facing eyes w/ depth perception, grasping hands, some have grasping tails • Live in a variety of environments

13. Order Chiroptera • Include: bats and the only mammals to fly • Modified front limbs w/ skin stretched between extremely long finger bones to hind limb. • Use echolocation for navigation and most have small eyes and large ears

14. Order Carnivora • 274 species including: dogs, cats, raccoons, bears, hyenas, otters, seals, and sea lions • Generally have long canine teeth, strong jaws, & clawed toes • Subphylum Pinnipedia: aquatic carnivores such as sea lions, seals, and walruses, have streamline bodies for efficient swimming

15. Order Artiodactyla • Ungulates = mammals w/ hooves; those with even numbers of toes make up the order Artiodactyla • Include: deer, elk, bison, moose, cows, sheep, goats, pigs, and camels • They are fast runners and use speed as a major defense • Usually herbivores their molars tend to be large and flat, for grinding materials • Have a chamber in stomach called rumen in which bacteria and microorganisms break down cellulose

16. Order Perissodactyla • Ungulates with odd number of toes make up order Perissodactyla • Includes: horses, zebras, rhinoceroses, and tapirs • Also have an adaptation to break down cellulose but instead of a rumen they have a cecum with microorganisms the break down cellulose releasing nutrients for the perissodactyl to absorb

17. Order Cetacea • 90 species of whales, dolphins, & porpoises • Have modified forelimbs = flippers • Breathe through blowholes located on the top of the head • Completely hairless except a few bristles on the snout • Thick blubber for insulation • Use echolocation for navigation and communication • Two groups of whales: toothed and baleen (filter feeders) whales

18. Order Sirenia • 4 species: manatees and dugongs • Inhabit tropical seas, estuaries, & rivers • Modified forelimbs for swimming - flippers • Lack hindlimbs but have a flattened tail for propulsion • Look like whales but are more closely related to elephants

19. Order Proboscidea • Characterized by boneless, trunked nose, or proboscis • Includes: Asian and African Elephant • Modified incisors called tusks for digging up roots and stripping bark from branches • Large jagged molars for grinding up plant material • Elephants have the longest gestation period of all animals (can take up to 22 months)