Characteristics
dry, scaly skin
amniotic egg
internal fertilization
respiration through lungs
exothermic (except birds and likely dinosaurs)
3 chambered heart (4 in birds, possibly in dinosaurs)
amniotic egg
internal fertilization
respiration through lungs
exothermic (except birds and likely dinosaurs)
3 chambered heart (4 in birds, possibly in dinosaurs)
REPTILES
ResponseThe brain is proportional to amphibian size/body ratio. Many reptiles have well-developed sight. They have Jacobson's organ, which is sensitive to odors (which is why snakes and other reptiles stick their tongues out, they're "smelling" with their tongues). Pit vipers (rattlesnakes, moccasins, copperheads) have a heat-sensitive pit under their eyes. They are ectotherms, rely on external sources for body heat.
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Circulation/Oxygen IntakeThe heart consists of two atria and one ventricle, making up a 3 chambered heart, The ventricle is divided by septum, so less deoxygenated/oxygenated blood mix than amphibians. Many reptiles are able to reduce oxygen requirements by being inactive. They have lungs, but 100% of gas exchange is done through them, unlike amphibians.
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ReproductionMost reptiles lay eggs on land (oviparity). American pit vipers store eggs inside female's body for an extended amount of time. They lay their eggs either very close to hatching or eggs hatch inside and live birth occurs (oviviparity).
Many reptiles provide no parental care. Some snakes guard eggs until hatches. Alligators and crocodiles provide much parental care. |
Feeding/DigestionThey have a wide range of feeding adaptations. Snakes can unhinge jaw and take in food larger than their heads. Crocodiles have extremely powerful bite. Digestive system identical to other vertebrates in most ways.
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CLADE AVES
Characteristics
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Feeding and DigestionBirds are endothermic, which requires a lot of food and oxygen. They lack teeth.
Once the food is swallowed, it enters an enlarged portion of the esophagus called the crop, where it stores and moistens food. Food then passes to first of a two part stomach (proventriculus) where it is chemically broken down with acids and enzymes. It passes then to the gizzard, where physical breakdown occurs. Birds often swallow small stones to aid in physical breakdown. |
MovementTheir bones are thin and hollow and many are fused, so the skeleton is more rigid. Large, keel-shaped breastbone (sternum) allows attachment for large flight muscles.
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CirculationBirds have a four chambered heart, and are similar to most other vertebrates.
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ResponseThey have a very large brain for boy size in most birds. They have complex behaviors, such as nest building, navigation, and parental care. Birds have great vision, especially raptors and owls. As well as good hearing, although they lack external ears.
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ReproductionSperm is produced in testes, anterior to kidneys. It passes through vasa deferent (vas deferent) into male's cloaca. During mating, the male presses his cloaca to the female and releases sperm.
Most females have a single ovary. Fertilized eggs move through oviduct where they get their hard shells. Birds usually have very high parental care. |
Parental Care
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Oxygen IntakeHigh metabolism requires a lot of oxygen, so they have an elaborate and efficient respiratory system. Some air passes from trachea (windpipe) into lungs while about 75% of air goes into air sacs (not used for gas exchange).
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MigrationMany birds migrate throughout the year ceding on food source. Many are thought to use Earth's magnetic field to navigate.
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