Snakes

1. Snakes

2. Classification Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes. Snakes are ectothermic, amniote vertebrates covered in overlapping scarles. Many species of snakes have skulls with many more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Living snakes are found on every continent except Antarctica and on most islands. Fifteen families are currently recognized, comprising 456 genera and over 2,900 species. Most species are non-venomous and those that have venom use it primarily to kill and subdue prey rather than for self- defence. Some possess venom potent enough to cause painful injury or death to humans. Nonvenomous snakes either swallow prey alive or kill by construction. They are carnivorous, eating small animals including lizards, other snakes, small mammals, birds, eggs, fish, snails or insects. Because snakes cannot bite or tear their food to pieces, they must swallow prey whole. The skeleton of most snakes consists solely of the skull, hyoid, vertebral column, and ribs, though henophidian snakes retain vestiges of the pelvis and rear limbs Anatomy of a snake: 1 esophagus, 2 trachea, 3 tracheal lungs, 4 rudimentary left lung, 5 right lung, 6 heart, 7 liver, 8 stomach, 9 air sac, 10 gallbladder, 11 pancreas, 12 spleen, 13 intestine, 14 testicles, 15 kidneys http://en.wikipedia.org/wiki/Snake

4. Eye • Fang • Mouth • Venom sac • Oesophagus • Trachea • Common carotid artery • Aortic arch • Auricle • Ventricle • Hepatic portal vein • Liver • Dorsal aorta • Stomach • Duodenum • Pancreas • Small intestine • Skin • Ovary/egg • Oviduct • Colon • Anus • Jugular vein • Abdominal vein • Lung • Kidney