Mammology

Characteristics

Orders

Reps

Main Characteristics of mammals:

• Endothermy - maintain high, constant body temperature through their metabolism

• Pelage - hair or fur made of protein called keratin covering all or part of the body for insulation & camouflage

• Four chambered heart (two atria & two ventricles) keep oxygenated & deoxygenated blood from mixing; double circulation

• Mammary glands in females are modified sweat glands that make milk containing sugars, proteins, & fats to nourish young

• Single jawbone • Specialized teeth for biting, cutting, & chewing • Highly developed brain (large cerebrum)

                                                                           

                                                                     

Echidna

Platypus

Monotremes

                                                                           

                                                                     

Echidna

Platypus

Mnotremes

Oviparous (egg laying) monotremes

Echidna Platypus• Oviparous • Not completely endothermic (lower body

temperature & it fluctuates) • Have a cloaca where wastes, eggs, & sperm are

emptied • Includes duck-billed platypus & spiny anteaters

or echidna

Monotremes

Viviparous (live birth) marsupials with incomplete uterine development• Found in New Guinea, Australia, & the Americas • Dominate animal in Australia due to lack of

competition from placental mammals • Known as pouched animals • Pouch called marsupium • Viviparous (live birth) • Tiny, immature young must crawl to mother's pouch after

birth • Young attach to mammary gland nipple to nurse until

able to survive outside of pouch • Includes opossum, kangaroo, wombat, & koala

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Placental Mammals

• Young carried in uterus & nourished by placenta

• Gestation periods (time of development within uterus) varies among species

• Adapted for life on land in water, and in air

• Mammal species make up 95 % of all animals

Specializations of the mouth & digestive system:

• Single jawbone • Incisors - specialized, chisel like front teeth for biting & chewing • Canines - pointed teeth or fangs behind incisors to help grip, puncture, &

tear prey • Bicuspids - teeth with two points behind the canines used to shear & shred

food • Molars - flattened back teeth to grind & crush • Baleen - thin plates in the roof of the mouth of some whales that strain food

from water • Microorganisms living in the gut help some mammals digest cellulose

from plants • Hoofed mammals (cows, sheep, giraffes...) have a four-chambered

stomach with bacteria living in the first chamber or rumen • Cud - digested food in the rumen that is regurgitated, swallowed, & then

chewed again to break down plant cellulose • Caecum - stomach chamber in elephants, horses, & rabbits that contains

bacteria to digest cellulose

Adaptations for Endothermy:

• High demand for oxygen • Right & left sides of heart separated by septum so

oxygenated & deoxygenated blood don't mix • Left side of heart pumps blood to lungs & back

(pulmonary circulation) • Right side of blood pumps oxygenated blood to body

cells (systemic circulation) • Diaphragm - sheet of muscle below lungs that moves up

& down in chest to change air pressure so gas moves into & out of the lungs

• Alveoli or air sacs in the lungs are surrounded by capillaries and increase the surface area for the absorption of oxygen

• Hair or fur and a fat layer insulates and prevents heat loss

Nervous System Adaptations:

• Largest vertebrate brain • Cerebrum surface is folded to increase

surface area without increasing volume • Cerebrum controls sensory organs, coordinates

movement, regulates behavior, & is responsible for memory & learning

• Have five major senses --- vision, hearing, olfaction (smell), touch, & taste

• Bats, whales, dolphins, porpoises  use echolocation (bouncing off of high frequency sounds) to navigate & find prey  

Reproductive Adaptations:

Each of the 3 mammal groups --- monotremes, marsupials, & placentals--- has a unique reproductive pattern

1. Monotreme females lay 1-2 leathery-shelled eggs containing yolk & incubates them with her body heat

Young monotremes are small & partially developed at hatching so depend on mother for protection and milk from mammary glands

2. Marsupials have short development period inside of the mother & newborns must crawl to the mother's pouch or marsupium after birth, attach to a nipple for milk, and finish developing 

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3. Placentals are the largest group of mammals

Gestation (period of development inside mother) is longer in placental mammals

Nutrients, wastes, gases exchanged through membrane lining uterus called the placenta

18 Orders exist

Order Insectivora: • Includes moles, hedgehogs, & shrews • Small with high metabolic rate • Found in North America, Europe, & Asia • Have long, pointed noses to grub for insects & worms • Teeth adapted to pick up & pierce prey • Adapted to live on & under ground, in trees, and in water • Shrews feed above ground & have claws to help

sweep invertebrates into their mouths • Moles live underground, have reduced eyes & no

external ears, and have short limbs to dig tunnels

Order Rodentia: • Largest mammal order (40% of all species) • Found everywhere except Antarctica • Includes squirrels, chipmunks, gophers, rats, mice, &

porcupines • Have two instead of four incisors • Teeth continue to grow throughout their life • Feed on hard seeds, twigs, roots, & bark • Gnawing keeps incisors sharp • High reproductive capacity • Guinea pig & capybaras are two rodents found in South

America

Order Lagomorpha:

• includes rabbits, hares, & pikas

• Found worldwide

• Have a double row of upper incisors & two large front teeth backed up by two smaller teeth

• Continuous growing teeth

• Herbivores

Order Edentata: • Includes anteaters, armadillos, & sloths • Found in North, Central, & South America • Means "without teeth" • Only anteaters are completely toothless • Armadillos & sloths have peg-like teeth without

enamel • Have long sticky tongues & claws on powerful front

paws to open ant hills & termite nests • Sloths are herbivores • Armadillos eat small reptiles, frogs, mollusks, & dead

animals

Order Chiroptera: • Only flying mammals • Includes bats found everywhere except polar regions • Front limb is modified into a wing with a skin membrane

stretching from the finger bones to the hind limb • Clawed thumb, extending from top edge of wing, is

used for walking, climbing, & grasping • Most are nocturnal (night active) • Use echolocation (emission of high frequency sounds

that bounce off objects) to navigate and locate food • Have small eyes & large ears • Feed mainly on insects • Tropical bats don't use echolocation, but have large

eyes & keen sense of smell to find fruit to feed on & nectar

Order Cetacea: • Includes whales, dolphins, & porpoises • Most inhabit oceans, but some dolphins

live in freshwater rivers • Have a fish shaped body • Forelimbs modified as flippers • No hind limbs • Broad, flat tails to propel through water • Breathe through a blowhole on top of the

head • Divided into two groups --- toothed

whales & baleen whales

• Toothed whales:1. Includes beaked, sperm, beluga, & killer whales; narwhals; dolphins; porpoises2. Have 1 to more than 100 teeth3. Prey on fish, squid, seals, & other whales

Baleen whales:1. Lack teeth2. Includes blue, grey, right & humpbacked whales2. Have baleen or thin plates of fingernail like material that hangs from the roof of the mouth3. Baleen strain shrimp & other invertebrates from water as food

Order Sirenia:

• Includes manatees & dugongs

• Large herbivores

• Inhabit tropical seas, estuaries, & rivers

• Front limbs modified into flippers

• No hind limbs

• Flattened tail for propulsion

Order Carnivora: • Found worldwide • Includes cats, dogs, raccoons, bears, hyenas,

& otters • Meat eaters (carnivores) mainly • Many feed on both plants & animals

(omnivores) • Have long canine teeth & strong jaws • Clawed toes for seizing & holding prey • Keen sense of sight & smell • Long limbs for running fast

Order Pinnipedia:• Aquatic carnivores • Includes sea lions, seals, & walruses • Streamlined bodies adapted for swimming • Steer & propel through water using broad, flattened tail • Called pinnipeds • Return to land to feed & give birth • Spend much of their time in cold water • Large land carnivores so this helps maintain

endothermy • Can remain under water for 5 minutes to an hour for

some species

Order Artiodactyla: • Known as ungulates or hoofed mammals • Have an even number of toes • Includes deer, elk, bison, moose, sheep, cows, caribou,

goats, pigs, & camels • Herbivores • Have large flat molars for grinding plants • Found everywhere except Antarctica • Cloven or split hooves • Fast runners (used for defense) • Have storage chamber called rumen in stomach where

bacteria break down cellulose • Stored food called cud is chewed again & then

swallowed to go through digestive system a second time

Order Perissodactyla:• Odd toed ungulates • Includes horses, zebras, rhinoceroses, & tapir • Most are native to Africa & Asia • Tapirs are found in Central & South America • Have a large, convoluted caecum or blind sac

near the small intestine where bacteria digest cellulose

Order Proboscidea: • Have a boneless trunk or proboscis • Includes the African & Asian elephant • Wooly mammoth is an extinct member of this order • Largest terrestrial mammal • Weigh more than 6 tons • Feed on plants up to 18 hours a day • Proboscis used to gather leaves from high branches & to suck water

without lowering the head • Modified incisors called tusks help dig for roots & strip bark • Jagged molars up to 30 cm long grind plants • Have the longest gestation period (20 months for females & 22

months for males) • Females can continue to have calves until they are 70 years old

Order Primates: • Includes 2 main groups --- Prosimians & Anthropoids • Most are omnivores • Have teeth suitable for a varied diet • Prosimians include lemurs, tarsiers, & lorises • Anthropoids include monkeys, apes, & humans • Anthropoids have a larger brain • Show more complex behaviors than other animals • Highly organized social groups • Gorilla is the largest primate • Have 2 forward-facing eyes for depth perception • Have grasping hands & most with grasping feet • Some have a grasping tail for life in trees • Live in a variety of habitats

Placental

Edentata (armadillos, anteaters, and tree sloths)

Insectivores (moles, hedgehogs, shrews)Chiroptera (bats)Primates (lemurs, monkeys, apes)Carnivores (wolves, dogs, coyotes, lions,

tigers, raccoons, weasels (includes otters, minks, skunks, pandas and bears, seals, sea lions, and walruses)

More Placental

Ungulates - (Hoofed Mammals) sheep, goats, camels, pigs, cows, deer, giraffes, and antelopes, rhinos, tapirs, horses

Cetaceans - Whales, Dolphins, and Porpoises

Proboscideans – Elephants

Sirenians – Manatees

Lagomorphs -hares, rabbits, and pikas