Coral Snake Body Structure
Although snakes are covered with scales, part of their integument consists of skin. The skin of most snakes is impermeable to water, which prevents dehydration and is a vital factor in enabling them to live in arid desert regions. The dry skin is made up of three layers. The inner layer is the thickest and contains the pigment cells, the middle layer is very thin and consists of growing and dividing cells, and the tough outer layer comprises various types of plates or scales made up of dead cells. The skin is very elastic, and the scales stretch apart when the snake is swallowing and digesting large prey. When the snakes body is distended after a large meal, the intestinal skin can easily be seen, and indeed, it is the areas of skin between the scales that gives the snakes body its flexibility.
Although we usually say that snakes crawl, they can actually move in different ways- serpentine movement, concertina movement, rectilinear creeping, and sidewinding. The type of movement used depends largely on the terrain.
Although not strictly “cold – blooded” as is generally believed, reptiles generate much less heat than mammals and birds. With no insulating layer of blubber, fur, hair, or feathers, they also lose heat far more rapidly. As a snake cools, it becomes less and less active, and below 35 – 39 degrees Fahrenheit (2-4 degrees Centrigade), it becomes completely torpid and may die.
Snakes gather information about the world in a very different way from us. While we rely mostly on sight and hearing, these senses are relatively poorly developed in snakes. Instead they rely on other stimuli, particularly scents, and in some cases, heat.
The most obvious features of snakes are their elongated body and lack of limbs. Primitive snakes often have remnants of pelvic girdles and hind limbs. These can be seen as tiny spurs or cloacal claws and are relics of the snake’s lizard like ancestors. The skeleton of most snakes consists of only a skull, a long vertebral column, and ribs. The spine is fairly uniform along the whole of its length and contains between 150 – 450 vertebrae, each with a pair of ribs. The vertebrae are linked by ball and socket joints, and by wing like projections or processes that limit the movement of each vertebrae to about 25 degrees each way. This prevents damage to the spinal cord, which runs through the center of the backbone, and protects the blood vessels and nerves that run alongside it.
Snake musculature is very complicated, consisting of many different individual muscles and muscle cords. It is the coordinated interaction of the muscles which gives snakes their smooth gliding motion. Three pairs of long muscle cords run along the backbone, connecting the vertebrae, and these are responsible for the smooth curving of the body. There are numerous muscles on the vertebral processes, which, when contracted, bring about the tight curves or loops in the snakes body. They have muscles connecting ribs together, and vertebrae to ribs. The skin muscles, which connect scales to scales and scales to ribs, are also important in locomotion.