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Lecture 24 - Vertebrata � Aves

Lecture 24 - Vertebrata � Aves - because they need a...

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Lecture 24 - Vertebrata – Aves 1. Feathers (fig. 31.23) – birds are the only extant species with feathers (people didn’t think birds were so closely related to us because they didn’t look back and see that dinosaurs had feathers that they used for protection); feathers on birds can be used for heat, flight, prevention of water-loss, and protection of skull 2. Anterior limbs, posterior limbs – posterior: used to perch, walk, and swim; anterior: flight; in an ostrich the wings are vestigial (not used anymore) 3. Other adaptations for flight a) Compact, streamlined body b) Fusion of bones – especially in finger area; allows for greater rigidity so they’re isn’t bending when you fly c) Jaw – no teeth: a lightweight, horny beak d) Hollow bones – spaces in the bones for lightness e) Lungs – have air sacs (big extensions of the lungs) that help the bones remain hollow; air sacs go in between organs and bones to keep it light 4. Heart – 4 chambered – no mixing of oxygenated and deoxygenated blood (they need this
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Unformatted text preview: because they need a high metabolic rate); no mixture of systemic and pulmonary systems; -Systemic-Pulmonary 5. Metabolic rate – have a very fast metabolic rate, eat a lot of seeds (high in calories)-Homoeothermic – means warm-blooded (we can regulate or body temperature to keep it fairly constant 6. Excretion – uric acid; no urinary bladder, they also have other modifications t make them light (such as having only one ovary) 7. Digestive system – have a crop (soft and muscular, for storing food) and gizzard (very muscular, for grinding food; often they eat gravel to help grinding) 8. Reproduction – internal fertilization, have a cloaca but no weenie, the tubes where the sperm come out of very close to the cloaca (female also has cloaca); have hard shells; mothers have to incubate the eggs because they are warm-blooded (in warm-blooded egg layers the eggs must be incubated) 9. Scales – on legs; remnants of reptilian ancestors...
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