CLASS MAMMALIA - MAMMALS
Extremely diverse class. Very advanced group with distinguishing feathers. They are endothermic with a high rate of metabolism. Aardvarks , anteaters, bats, elephants, marsupials, monotremes, primates, rodents, apes, cats, dogs, tigers, mice, moose, beavers, gorilla, sloths, pandas, hamsters, horses, whales, dolphins, giraffes, skunks, squirrels, etc.
HAIR & MAMMARY GLANDS
Mammary glands produce milk that nourish developing young mammals. Hair helps: insulate the body and act as a form of: camouflage (tigers), sensory devices (whiskers on cats), waterproofing (sea otters), signaling (white-tailed deer), and defense (porcupine quills).
CIRCULATORY SYSTEM
Efficient, closed circulatory system with a four chambered heart. Very similar to the circulatory systems of birds. Efficient transportation of oxygenated blood all over the body (as mammals, like birds, are constantly active).
BRAIN
Mammals have the largest and most developed brains, especially the cerebrum and cerebral cortex, of all animals. Their size is due to weight and skull volume. The ratio of brain mass to body mass is not always the same. Four mammals that have BIG brains both in size and intelligence are humans, dolphins, sperm whales, and elephants. The folding of the mammalian brain allow the bran to have a larger surface area for nerve connections while still allowing it to fit inside of a skull. This larger brain allows for more complex forms as behavior as wells as keener, sharper senses (e.g sense of smell of dogs).
MAMMAL GROUPS
MONOTREMES
Species include platypus and echidna (spiny anteater). Found only in Australia and New Guinea. Not very diverse today. They lay eggs rather than give birth. Reptilian bone structure in the shoulder area, lower body temperature than most mammals, and unique mix of chromosomes with characteristics similar to both mammals and reptiles.
MARSUPIALS
All marsupials live in Australia, New Zealand, Central and South America. One marsupial (the opossum lives in North America, They give birth to tiny embryos that are attached to a mother's nipple. Embryos grow in an external pouch attached to the mother's abdomen (or marsupium). Some offspring are born and crawl into the mother's pouch eight days after fertilization! This group includes kangaroos, wallabies, possums, wombats, Tasmanian devils, and koalas.
PLACENTAL
Diverse group. 4,000 species known. Most mammals. They include mostly rodents, bats, whales, elephants, shrews, armadillos, dogs, cats, cattle, horses, bears, human, etc . They all bear live young. Babies are nourished before they are born in the mother's uterus through the placenta (specialized embryonic organ attached to the uterus wall). Brains of placental mammals are the most developed and largest of all of the mammals.
HAIR & MAMMARY GLANDS
Mammary glands produce milk that nourish developing young mammals. Hair helps: insulate the body and act as a form of: camouflage (tigers), sensory devices (whiskers on cats), waterproofing (sea otters), signaling (white-tailed deer), and defense (porcupine quills).
CIRCULATORY SYSTEM
Efficient, closed circulatory system with a four chambered heart. Very similar to the circulatory systems of birds. Efficient transportation of oxygenated blood all over the body (as mammals, like birds, are constantly active).
BRAIN
Mammals have the largest and most developed brains, especially the cerebrum and cerebral cortex, of all animals. Their size is due to weight and skull volume. The ratio of brain mass to body mass is not always the same. Four mammals that have BIG brains both in size and intelligence are humans, dolphins, sperm whales, and elephants. The folding of the mammalian brain allow the bran to have a larger surface area for nerve connections while still allowing it to fit inside of a skull. This larger brain allows for more complex forms as behavior as wells as keener, sharper senses (e.g sense of smell of dogs).
MAMMAL GROUPS
MONOTREMES
Species include platypus and echidna (spiny anteater). Found only in Australia and New Guinea. Not very diverse today. They lay eggs rather than give birth. Reptilian bone structure in the shoulder area, lower body temperature than most mammals, and unique mix of chromosomes with characteristics similar to both mammals and reptiles.
MARSUPIALS
All marsupials live in Australia, New Zealand, Central and South America. One marsupial (the opossum lives in North America, They give birth to tiny embryos that are attached to a mother's nipple. Embryos grow in an external pouch attached to the mother's abdomen (or marsupium). Some offspring are born and crawl into the mother's pouch eight days after fertilization! This group includes kangaroos, wallabies, possums, wombats, Tasmanian devils, and koalas.
PLACENTAL
Diverse group. 4,000 species known. Most mammals. They include mostly rodents, bats, whales, elephants, shrews, armadillos, dogs, cats, cattle, horses, bears, human, etc . They all bear live young. Babies are nourished before they are born in the mother's uterus through the placenta (specialized embryonic organ attached to the uterus wall). Brains of placental mammals are the most developed and largest of all of the mammals.