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Class Aves (Chapter 31.2). Please set up your notebook for Cornell Notes. What is a bird? Characteristics Vertebrate, maintain constant body temp, have feathers, two legs covered in scales, and front limbs modified into wings Feather made of proteins, helps bird fly and keep warm
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Class Aves (Chapter 31.2) Please set up your notebook for Cornell Notes
What is a bird? • Characteristics • Vertebrate, maintain constant body temp, have feathers, two legs covered in scales, and front limbs modified into wings • Feather made of proteins, helps bird fly and keep warm • Two types • Contour provide lifting force for flight • Down keep bird warm
Form and Function • Homeostasis • Endotherms maintain a constant body temp • Fast metabolism that requires a lot of energy
Feeding • Bird beaks are adapted for type of food eaten • Digestive system • Mouth – no teeth • Crop – food stored and moistened in crop located on lower section of esophagus • Stomach • If food is soft, stomach is expandable to store large amounts of food • If food is hard, use muscular gizzard that grinds food • In some birds gizzard contains gravel • Small intestine – break down of food is completed and nutrients are absorbed • Large intestine • Cloaca
Respiration • Highly efficient • Flow • When bird inhales, air enters air sacs in body cavity and bones • Air then flows thru lungs • Lungs contain small tubes lined with tissue for gas exchange • Air flows to trachea and out of body • Helps birds maintain high metabolism • Helps birds fly at high altitudes
Circulation • 4 chambered hearts and two separate circulatory loops • Deoxygenated blood enters right atrium, then to right ventricle, then to lungs then to left atrium, then left ventricle then body • Excretion • Nitrogenous waste is converted into uric acid in kidneys and deposited in cloaca • Water is reabsorbed in cloaca and white, pasty uric acid crystals leave cloaca
Response • Well developed sense organs • Brain can quickly interpret and respond to signals • Cerebrum controls flying, nesting, care of young, courtship and mating • Cerebellum coordinates movement • Medulla oblongata basic body functions (heart beat) • Birds have well developed optic lobe and eyes • Can see in color • Good sense of hearing • Not so good sense of smell or taste
Movement • Some birds walk, swim, or run • Other birds fly • Flying adaptations • Large bones fused together for form rigid skeleton • Hollow bones with scaffolding • Large chest muscles attached to sternum (keel)
Reproduction • Mating birds press cloacas together to exchange sperm • Males of some species have a penis • Amniotic egg with hard shell • Must be incubated • Precocial young born with down and can run or swim soon after hatching • Quail, duck • Altricial young born naked and unable to see, parents must carry food to the nest • Sparrow, robin