Characteristics of Mammals

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

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

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

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

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

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

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.

Order Edentata

• Includes: anteaters, armadillos, & sloths

• Name of the order means “toothless” but only anteaters are completely toothless

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

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

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

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

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

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

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

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

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

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)