Section 2 Characteristics of Mammals 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
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.