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ZOOLOGY MAMMALS MAJOR CHARACTERISTICS Endothermy Hair Completely divided heart Milk – mammary glands Single Jaw Bone Specialized teeth ENDOTHERMY Body temperature regulation through metabolism and insulation Homeostasis Allows mammals to live in cold climates Allows for energy to perform strenuous activity for extended periods Faster metabolism requires more food and oxygen ENDOTHERMY Adaptations to environment - blubber – whales, seals - thick fur – polar bears - large ears – elephants - panting – lions, dogs HAIR Provides insulation and protection Made of the protein keratin DIVIDED HEART Efficient Two atria Two ventricle Septum completely divides ventricles preventing mixing of oxygen rich blood and oxygen depleted blood. MILK Mammary glands located on thorax Milk contains carbs, proteins, and fats Modified sweat glands SPECIALIZED TEETH Breakdown of food begins with chewing Provides large surface area for enzymes to digest food Incisors – cut Canines – grip Premolars – shear, cut, shred Molars – grind, crush SINGLE JAW BONE Lower jaw made up of one bone Mammal fossils often identified by jaw bone RESPIRATORY SYSTEM Efficient Large surface area Two mechanisms – diaphram, rib-cage muscle DIGESTIVE SYSTEM Special adaptations for plant digestions Rumen – four part stomach “chewing the cud” Cecum – large sac branched from small intestine – allows for fermentation Both utilize microorganisms NERVOUS SYSTEM Mammal brain 15 times heavier than fish, reptile or amphibian Large cerebrum – evaluates input from sense organs, controls movement, regulates behavior DIVERSITY OF MAMMALS Monotremes – oviparous Marsupials – viviparous Placental – longer development in uterus receives nourishment from placenta MAMMALIAN ORDERS Monotremata Marsupialia Insectivora Chiroptera Dermoptera Primates Scandentia Macroscelidea Tubulidentata Lagomorpha Rodentia Pholidota Carnivora Cetacea Artiodactyla Perissodactyla Hyracoidea Sirenia Proboscidea MONOTREMATA Lay eggs Ancient Platypus Two echidna species (spiny anteater) MARSUPIALS Super order marsupialia Seven orders 280 species Most live in Austrailia Only U.S. species is the Virginia opossum XENARTHRA 30 species Anteaters, armadillos, sloths Feed on insects with long sticky tongue Many are toothless Have unique structure of lumbar vertebrae Strong teeth, claws LAGOMORPHA Rabbits, hares, pikas Native to many countries Double row of upper incisors that continue to grow Herbivore RODENTIA Largest mammalian order Found on every continent except Antartica 1800 species Mice, rats, porcupine PRIMATES 235 species Apes, monkeys, lemurs Humans Forward facing eyes allows for dept perception Wide range of sizes Grasping hands and feet CHIROPTERA Only flying mammals Bats 900 species Modified forelimb Echolocation Large ears INSECTIVORA 390 species Shrews, hedgehogs, moles Feed primarily on insects Long pointed nose and sharp teeth allow them to hold prey CARNIVORA 274 species Feed on meat Strong jaws Large teeth Claws Pinnipeds – aquatic carnivores (sealions) ARTIODACTYLA Ungulate Even number of toes Most are ruminants Deer Cattle Giraffes Pigs PERISSODACTYLA Ungulate Odd number of toes Horses Zebras Rhinos Tapirs Have a cecum CETACEA Related to Artiodactyla Whales, dolphins Adapted to aquatic environments Hairless except for snout SIRENIA Related to elephants Look similar to whales due to convergent evolution Live in tropical seas, estuaries, and rivers Lack hind limbs PROBOSCIDEA Nose modified into long boneless trunk Elephant Asian and African Modified incisors called tusks
