1. Mammals

2. Mammals Characteristics
Integument & Derivatives
Skin is thicker than other vertebrates
Epidermis – thinner, protected by hair
Dermis – thicker
Glands
Sweat Glands
Eccrine glands
Secrete a watery fluid, draws heat away when evaporated
Apocrine glands
Secrete milky fluids that dry on skin to form a film
Scent Glands
Used for communication, marking territory, warning or defense, attracting mates
Sebaceous Glands
produce a substance called sebum which is responsible for keeping the skin and hair moisturized.
Mammary Glands
Secretes milk

5. Mammals Characteristics
Integument & Derivatives
Hair – two kinds of hair forming their pelage (fur coat)
Coarse & longer guard hair for protection
sometimes modified to form defensive spines
(as in porcupines, in which the cuticular scales elongate to form barbs that make it difficult to remove imbedded spines),
Dense & soft Underfur
made up of wool (ever-growing hairs),
fur (relatively short hairs with
definitive growth), and/or velli
(down or fuzz).
Mammalian embryos (including
humans) also are often covered with
a pelage, called lanugo, which is a kind
of a fuzz.

6. Mammal Characteristics
Food & Feeding
Some have highly specialized diets, others
thrive on diversified diets
Teeth reveal the life habit of a mammal
Incisors – simple crown/sharp edges for snipping/biting
Canines – long conical crowns, specialized for piercing
Premolars & Molars – compressed crowns for shearing, slicing, crushing, or grinding.
Most grow two sets of teeth
Deciduous (or milk) teeth – temporary set
Permanent teeth – when the skull has grown large enough to support a full set
Only incisors, canines & premolars are deciduous; molars are never replaced

7. Mammal Characteristics
Feeding Specializations
Insectivores
Shrews, moles, anteaters, bats
Feed on small invertebrates – worms, grubs, insects
Have teeth with pointed cusps
Herbivores
Feed on grasses & other vegetation
Browsers & grazers – horses, deer, antelope, cattle, sheet
Gnawers – rodents, rabbits
Canines are absent or reduced
Carnivores
Foxes, dogs, weasels, wolverines, cats
Feed mainly on herbivores
Omnivores
Pigs, raccoons, bears, most primates
Feed on plants & animals

9. Mammal Characteristics
Movable eyelids & fleshy external ears
Four – chambered heart
Highly developed brain
Endothermic
Internal fertilization
Embryos develop in a uterus
Young nourished by milk from mammary glands

10. Reproduction Most mammals have a definite mating seasons
Females fertility is restricted to a specific time (estrous cycle)
Three different patterns of reproduction
Monotremes
Egg-laying (oviparous) mammals
Duck-billed platypus – embryos develop for days in uterus.
Thin leathery shell secreted around embryo before eggs are laid.
Hatch underdeveloped after 12 days. Feed on milk after they hatch

11. Reproduction Marsupials Pouched, viviparous mammals
They give live birth, but they do not have long gestation times
give birth very early and the young, helpless embryo, climbs from the mother's birth canal to the nipples, it grabs on with its mouth and continues to develop, often for weeks or months depending on the species.

12. Reproduction Placental mammals
Placental mammals all bear live young, which are nourished before birth in the mother's uterus through a specialized embryonic organ attached to the uterus wall, the placenta.
Length of gestation is longer than marsupials
Larger the mammal the longer the gestation
Mice – 21 days
Cats & Dogs – 60 days
Elephants – 22 months