Mammals

MAMMALS Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia

There are about 5000 species of living mammals. Approximately 300 species are considered endangered, including most cetaceans, cats (except domestic cats), otters, and primates (except humans).

Mammals – 3 subclasses – based on the way they reproduce Subclass Prototheria –Order Monotremata – lay eggs w/leathery shells and nourish the young with milk from belly pores; Examples spiny anteater and the duck billed platypus;

Monotremata 4 species of echidna- spiney anteaters Platypus SEE VIDEO!

Subclass Metatheria - Marsupials; Short period of time inside mother, young then partially develop in mothers pouch; About the size a of a grain of sand when born, then climb to pouch. Example kangaroo, Tasmanian devil, wombat, opossum, koalas

Wombat Tasmanian Devil Koala Kangaroo- video

What animal goes on a honeymoon, and 13 days later gives birth? It lived during the age of dinosaurs: fossil remains have been found from 70 million years ago. It can eat almost anything. It loves to eat insects (beetles, cockroaches, and so forth). It eats snails and slugs. It catches and eats roof rats. It also eats cat food, dog food, people food. It has thumbs on its hind feet! It is very quiet, although it can make some sounds. Learning and discrimination tests rank it above dogs, and more on the level of pigs. Give Up? More clues... It does not have a territory, but is always on the move, going to wherever the food is. Females stay in a smaller area while they care for their young. It puts up a terrific bluff if cornered and can give the appearance of being really good at defending itself. NOTE: it is not good at defending itself! Big Clue! If attacked and unable to fight or run from danger, it collapses and appears to be dead!

An Opossum!

Subclass Eutheria – Placental animals; carry young inside uterus until birth; 17 orders; Only suborder evolved to be found on land, sea, and air; 95% of all mammals are placental.

What is a mammal? Mammary glands – produce and secrete milk to nourish the development of the young. Diaphragm – domed respiratory muscle between thoracic and abdominal compartments; allows large oxygen intake.

Hair – long, slender filament; thought to have evolved from scales; provides insulation by retaining heat, provides waterproofing, camouflage, communication w/other animals, and protection.

Endothermic 4-chambered heart specialized teeth – example – beaver (incisors), wolf (canines), horses (molars and premolars) highly developed nervous system and senses; more folds in brain provides more surface area.

Glands – cells or group of cells that secrete fluids; Appendages modified for food gathering in their habitat. Example – primates have an opposable thumb;antelope have strong, slender legs for fast running Have a single jaw bone 3 middle ear bones

HAIR AND OTHER DERIVATIVES Pelage – coat of hair 2 types of hair 1. guard hair - coarse, longer hair; protects against wear and may provide coloration

2. underhair – used for insulation by trapping a layer of air; dense, softer.

3 types of horns 1. True horn – hollow w/a core made of bone arising from skull; can be found in both sexes; not normally shed (antelope, cattle, sheep)

2. Antlers – solid bone, covered w/velvet that sheds as it grows; only in males; shed after each breeding season. For several years each new pair is larger and more elaborate than year before (elk, moose, deer, caribou)

3. Rhinoceros horn – not attached to skull TEETH- adapted to food source. Deciduous teeth are replaced by permanent teeth (except molars)

4 kinds of teeth 1. incisors – front teeth; central and lateral (beavers- large incisors for gnawing and nipping) 2. canines – longer teeth; 2 top/2 bottom; used to catch, kill and tear prey (wolf)

3. premolar – next to canines; prominent in grazing animals 4. molar – back teeth; prominent in grazing animals

Feeding specializations Insectivores –feed mainly on insects; moles, anteaters, shrews and most bats Herbivores – feed on grasses and other vegetation.

Browsers, gazers (cows) and gnawers (rodents and rabbits) Carnivores – feed mainly on herbivores Omnivores – feed on plant and animals (pigs, rats, primates)

GLANDS Eccrine glands secrete fluids directly onto the skin. Apocrine glands secrete fluids into ducts which are then taken to the skin. sebaceous (oil) – lubricates and waterproofs skin and hair

sudoriferous (sweat) – used to draw heat away from body; mixture of salt, urea, and water in which microorganisms convert to odorous products scent (musk) – found around face, feet, or anus; used for defense, species and sex recognition, and territorial behavior.

mammary gland – present, but nonfunctional, in males; monotremes lack nipples, milk is discharged into depressions in belly where it is lapped up; milk contains water, carbohydrates, fat, protein, minerals, and antibodies.

REPRODUCTION Most have definite mating season, usually winter or spring to coincide w/most favorable time for rearing young after birth. Female can copulate during its estrous cycle, during which she will ovulate (said to be in “estrus”). Ovulation ended by menstruation.

Males can mate at anytime. Some off spring born alert/bright eyed (antelope born ready to run), others blind and naked (mice)

Gestation is the period of time in which young develop inside uterus; the larger the animal, the longer the gestation and the fewer offspring.