Mammals

Test #5

Class Mammalia

• Have hair

• Most have an active metabolism

• Endothermic

• Efficient respiratory and circulatory systems (4 chambered heart)

• Diaphragm helps with lungs

• Has mammary glands that produce milk

Reproduction

• Most are born and not hatched

• Internal fertilization

• Embryo develops in the uterus

• Uterus forms a placenta- where nutrients diffuse into the embryo’s blood

Brain

• Usually larger

• Capable of learning

• Care for young longer to teach them skills

• Needed for survival

Feeding

• Teeth come in a variety of shapes and sizes that are adapted to eat different kinds of foods– Incisors and canines-shearing or tearing– Premolars and molars- grinding

• Jaws that are different from reptiles

Major Orders of Mammals

1.Monotremes

2.Marsupials

3.Plancentals

Monotremes

• Comes from the greek word monos (single) trema (hole).

• Have a cloaca• Lack teeth as adults• Have a spur on the legs in the ankle

region that contains venom in a platypus.• Legs are on the sides of their bodies like

reptiles instead of underneath the body like most mammals.

Monotremes

• Platypuses and Echidnas (spiny ant eaters) – Only mammals that lay

eggs• Contain yolk to nourish

young

– Have hair and produce milk– No nipples-glands secrete

milk on stomach and the babies suck milk from fur

– Found in Australia and New Guinea

– Infant echidnas are known as puggles.

Marsupials

• Opossums, Kangaroos, Bandicoots, and Koalas– Born very early in development

and completes embryonic development while nursing

– Young are held in a pouch called a marsupium

• Example: The red kangaroo is the size of a honeybee at birth and is born 33 days after fertilization.

– It then crawls from the exit of the reproductive tract to the pouch

– Front limbs are more developed at the time of birth for climbing.

Marsupials

• Reproduction– Females have 2 vaginas that lead to two

separate uteruses– Females have a third canal that is used for

birth– Males have a pronged penis that is only used

to transfer sperm (not used for urination).– Both sexes have a cloaca

Placentals

• Gets it’s name from the placenta– Organ that transfers nutrients, oxygen, carbon

dioxide, and wastes between mother and embryo

– Allows the embryo to develop for a longer time period inside the mother

• Rats: a few weeks• Elephants: two years

12 Major Orders

• Insectivores (shrews, hedgehogs, moles)– Insect eaters– Have long narrow snouts and sharp claws for

digging

• Sirenians (Manatees, dugongs)– Herbivores– Live in rivers , bays and warm costal waters

scattered throughout most of the world– Slow, large, fully aquatic mammals

12 Major Orders

• Cetaceans ( Whales, dolphins)– Live underwater but must come to the surface to

breathe– Most live and breed in the ocean

• Chiropterans (Bats)– Winged mammals– Only mammals that can fly– 1/5 of all mammalian species– Eat mostly fruit, insects, or nectar but some feed on

the blood of other vertebrates

12 Major Orders

• Rodents (Mice, rats, voles, squirrels, beavers, porcupines, gophers, chipmunks, gerbils, prairie dogs, chinchillas)– Have a single pair of long, curved incisor teeth in

upper and lower jaws– Gnaw wood and other tough plant material

• Perissodactyls (horses, tapirs, rhinoceroses, and zebras)– Hofed animals with an odd number of toes on each

foot

12 Major Orders

• Carnivores (dogs, foxes, bears, racoons, walruses)– Stalk or chase prey by running or pouncing, then kill

with their sharp teeth or claws– Some eat plants and meat

• Artiodactyls (Cattle, sheep, goats, pigs, ibex, giraffes, hippopotami, camels, antelope, deer, gazelles)– Hoofed mammals have an even number of toes on

each foot– Mostly large grazing animals

12 Major Orders

• Lagomorphs (hares and rabbits)– Herbivores– Only have a pair of incisors in the upper jaw– Most have hind legs adapted for leaping

• Xentharthrans (sloths, anteaters and armadillos)– Have simple teeth without enamel– Some have no teeth at all

12 Major Orders

• Proboscideans (elephants)– Animals with trunks– Used to include mastodons and mammoths,

but today we only have African and Asian elephants

• Primates (lemurs, tarsiers, apes, gibbons, macques, humans)– Have a highly developed cerebrum and

complex behavior

Primates

• Early primates– Insectivores– Cretaceous period– Probably small and tree dwelling because they had

limber shoulders to swing on trees and hands to hang on branches

– Claws were replaced with nails– Sensitive, long fingers and toes– Eyes are close together in front of their face

(binocular vision)– Have depth perception that helps with swinging– Increased parental care

Primates

• 2 Sub orders– Prosimians “pre-

monkeys”• Lemurs, lorises, pottos,

and tarsiers• More like early primates

– Anthropoids• Monkeys, apes, and

humans• Fossils indicated they

were already established in Africa and Asia 40 mya

Prosimians

• Small

• Nocturnal primates with large eyes adapted to see in the dark

• Many have dog-like snouts

Anthropoids

• Anthropoid means “human-like primates”

• Branched into two based on evolutionary history

• New World monkeys and Old World monkeys

Monkeys

• Came to South America by raft (continents were closer together then) or by migration

New World Monkeys

• Arboreal-live and swing on trees– Have long prehensile

tails that coil around branches

– nostrils that open to the side

Old World Monkeys

• Ground dwelling and arboreal– Tail is not for swinging

and the nostrils open downward

– They also have tough seat pads on their behinds

– Most are diurnal (active during the day)

– Usually live in bands– Hominids are larger

Hominids (or “Great Apes”)

• Have 4 Genera

1. Hylobates (gibbons)

2. Pongo (orangutans)

3. Gorilla (gorillas)

4. Pan (chimpanzees) 5. Humans

Hominids• Are larger than monkeys• Long arms, short legs, and no

tails• All apes can swing from

branches– Only gibbons and orangutans

are arboreal• Gorillas and chimpanzees are

very social• Apes have proportionally

larger brains than monkeys• Apes behavior is more

adaptable• Can walk upright and grasp

with thumbs