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Chapter 43 Mammals. Section 2 Characteristics of Mammals. Endothermy. Allows mammals to live in cold environments and remain active Provides energy for strenuous activities like migrating Fast metabolism requires more energy Cold environments- blubber & thick furred animals.
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Chapter 43Mammals Section 2 Characteristics of Mammals
Endothermy • Allows mammals to live in cold environments and remain active • Provides energy for strenuous activities like migrating • Fast metabolism requires more energy • Cold environments- blubber & thick furred animals
Circulatory System • Two atria and two ventricles • Septum- wall of tissue separates ventricles • No mixing of deoxygenated and oxygenated blood • Complete septum- adaptation that allows mammals’ bodies to transport oxygen more efficiently
Respiratory System • Efficient gas exchange • Large lungs- many alveoli- small sacs where gas exchange occurs • Expand ribcage and take in air through lungs • Diaphragm- contraction enlarges thorax and increases thoracic activity- breathing
Feeding & Digestion • Incisors- cut food • Canines- grip, puncture, & tear • Premolars- shear, shred, cut, or grind • Molars- grind, crush, or cut • Baleen whales- baleen- thin plates of keratin- trap prey
Digesting Plants • Cellulose- polymer of sugar glucose- hard to digest • Stomach- four chambers • One chamber = true stomach • Rumen- another chamber- contains symbiotic microorganisms
Digesting Plants • Partly digested in rumen, then regurgitated, chewed again and swallowed again • Animals may regurgitate multiple times • Ruminant animals- cows, sheep, goats, giraffes, deer
Digesting Plants • Horses, zebras, rodents, rabbits, & elephants- cecum • Cecum- large sac that branches from small intestines and ferments food • Animals with a cecum do not chew cud
Nervous System • Mammal brain is large • Cerebrum- outer region of brain • Sense organs, movements, behavior, memory, learning • Vision, hearing, smell, touch, taste • Echolocation- emit high-frequency sound-waves, which bounce off objects
Development • Mammals develop differently
Monotremes • Lay one to two eggs • Incubate by body heat • Yolk nourishes young • Once young hatch, female feeds young milk until fully developed
Marsupials • Develop in uterus for short time • When only 2-3 cm, young develop in mother’s pouch and attach to a nipple to feed • Young stay in pouch for several months
Placental Mammals • Well-developed young are born live • Placenta provides nourishment & oxygen • After birth, infants feed on milk for several weeks or months
REVIEW!!! • A mammal eats about ten times as much food as a lizard of the same size. Explain this difference. • Describe the function of a rumen.