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Reptiles and Birds

+Reptiles

+Reptiles Body Plan

Contrary to common belief, reptile scales can be smooth or rough, and they are never slimy.

The basic reptilian body plan includes a well developed skull, a backbone and tail, two limb girdles, and four limbs.

The only two reptiles that do not follow this plan are turtles (which have a hard shell fused to their vertebrae) and snakes (which have no limbs).

Reptiles are “heated from the outside.” Because of this, they are called ectotherms and they lack effective insulation so they need to gain additional heat by laying in the sun.

Skeletal

+Feeding

Some reptiles are herbivores while others are carnivores.

The way reptiles get their prey vary. Some snakes paralyze with a powerful venom while others suffocate their prey by wrapping tightly around them.

+Respiration and Internal Transport Since gasses are unable to diffuse easily across the scaly

skin of reptiles, all reptiles have well-developed lungs, to help in this area.

To help with this area also, reptiles have muscles attached to their rib cage to enable their lungs to inflate and deflate. Diagram

Additionally, reptiles have a double-loop circulatory system to allow the blood to first pass through the lungs and then to the remainder of the body. Diagram

Although there are exceptions, most reptiles have a “not quite four-chambered heart because the oxygenated and deoxygenated blood mix in a few areas.

+Excretion

Reptiles that live primarily in the water (like alligators and crocodiles) excrete most of their nitrogenous wastes in the form of ammonia.

Many other reptiles covert their waste into uric acid. The excretion of uric acid presents two benefits over ammonia:

1. Uric acid is less toxic. 2. It is not soluble in water.

As a result, reptiles with uric acid excretion are better able to conserve water because the urine flows into an organ called the cloaca, where crystals of uric acid form a semisolid paste. By getting rid of these dry wastes, water is able to be conserved. Diagram

+Nervous System and Sense Organs Reptiles have brains similar

to Amphibians, except reptiles have a bigger cerebrum and cerebellum.

Reptiles have really good vision.

According to the Biology textbook, most snakes probably see more colors than you do!

+Movement

Reptiles have large and strong legs that easily support their body weight.

Their strong limbs allow for many actions to be performed, including running, swimming, burrowing, and climbing.

+Reproduction

Reptiles are the first vertebrates to live without relying on water.

This is because their eggs are fertilized internally, and then develop into an amniotic egg meaning an embryo surrounded by a leathery external shell.

+Birds

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+Works Cited

Turtle diagrams: http://www.bio.davidson.edu/Courses/anphys/2000/Pleasants/resp.htm http://www.bio.davidson.edu/Courses/anphys/2000/Pleasants/circ.htm

All pictures are from clipart!