Hobbies And Interests
Skin
Reptiles have a dry, tough, scaly skin which provides protection from drying out in hot arid climates. Their epidermis is filled with fat, which helps keep water inside the animal. Scales made out of beta keratin form from the epidermis and provide physical protection. Their thick dermis contains chromophores: cells that give reptiles their coloring.
Jaws
Reptile jaws are designed to snap closed quickly but once closed they don't need to exert much energy to keep them closed. This adaptation allows them to quickly seize prey and hold onto it without using much force.
Heart
Reptiles have an efficient circulatory system with an incompletely partitioned heart. This allows blood to bypass the lungs while diving in water or during aestivation which is similar to hibernation.
Lungs
Reptilian lungs are well developed. Their lungs suck air into them by creating negative pressure. By expanding the thorax, pressure inside the lungs drops and air is drawn in. This is similar to how mammals breathe. However, mammals have a diaphragm which aids in respiration; reptiles do not have a diaphragm.
Water Conservation
By excreting concentrated uric acid instead of watery urine or ammonia, reptiles conserve water. They also have salt glands to secrete excess salt without the accompanying loss of water.
Fertilization and Eggs
Fertilization takes place internally after a male and female mate. The egg forms internally and is excreted to the external environment, where the embryo finishes developing. Reptile eggs can survive in drier environments due to the amnion and shell which keep moisture in the egg. The chorion and allantois, present in all amniotes, allow an exchange of carbon dioxide and oxygen with the atmosphere, which enables the embryo to grow large quickly. A large yolk sac provides nourishment for the quickly growing embryo. In some reptiles, a majority of embryo development takes place in the female reproductive tract, decreasing the time that the egg is susceptible to environmental or physical damage.
Nervous System
Reptiles have small brains, but relatively fairly large cerebrums. Their hearing, vision, taste and sense of smell are better developed than amphibians'. Snakes and lizards have a Jacobson's organ, which is a highly developed olfactory chamber present in the nose or the tongue. Reptiles whose Jacobson's organ is located in the tongue rapidly stick out their tongue repeatedly to sense odors in the environment.