Wednesday, March 18, 2009

General Snake Information

From Eggs or Live Birth

Most snakes hatch from eggs (oviparous). Racers, bullsnakes, milk snakes and green snakes are common egg-layers. The eggs are usually white and have an oblong, leathery-like shell. Eggs are normally deposited in a location that is moist and relatively warm such as sand, sawdust piles, rotting stumps, or under rocks. Snake eggs are not incubated like bird eggs; the warmth of the substrate and rays of the sun control the incubation process. Incubation may last up to 60 days before the young are fully developed and hatch. Other snakes, such as garter snakes and rattlesnakes, have live birth of the fully developed young (ovoviviparous). The fertile eggs develop within the maternal body.


All snakes are predators. They must locate their prey before they seize it. Snakes will eat whatever they can catch, master, and swallow. Their prey is located by their senses of vision, smell, or thermosensitivity. The food they consume depends upon the animal’s size and the environment where it lives. Rattlesnakes eat rodents such as mice, ground squirrels, and the young of prairie dogs and cottontail rabbits. They also eat other snakes, lizards, birds, and insects. The average snake will consume two to three times its own weight in various food items between the spring and fall months when the snake is away from its winter den.


Snakes do not have external ears and are probably deaf to most sounds.They "hear" by sensing ground vibrations with their belly scales and lower jaw.


A snake’s vision is mainly used for detecting movement of prey. They have difficulty seeing motionless prey or enemies. Objects probably appear as a blur at 40 feet, but at 10 to 15 feet, the objects appear sharper. The vision of many snakes, like the rattlesnake, is better suited for nocturnal searching. Some species, such as racers and garter snakes, have eyes specialized for daytime activity. Snakes appear to stare at their prey because they have no eyelids. The eyes of snakes are lidless, but are protected by a tough, transparent covering, or scale, that is shed with the skin. The pupil or the black portion of a rattlesnake’s eye is elliptical, not round as found with the nonvenomous snakes.

(Figure compliments of Missouri Dept. of Conservation)

All snakes are covered with scales, which are thickened areas of a thin outer skin layer. Under this layer is another skin layer that contains pigment cells that give a snake its distinctive color pattern. The arrangement of color patterns, type of scales, and scale rows are used to identify the various species.

Rattlesnakes, bullsnakes, and garter snakes have what is called a keeled scale (Figure 3 below), which has a ridge on the center of each scale. Other snakes, such as the racer and milk snake, have smooth scales (Figure 2 below), with no ridges. The skin of a snake is dry, not slimy. Molting, or skin shedding, is repeated periodically throughout a snake’s life. Just prior to shedding, the skin becomes dull and dry looking and the eyes become cloudy or blue-colored. After a few days, the eyes clear and the snake "crawls" out of its old skin, which peels backward over the body from head to tail, in one piece. A new, larger, and brighter layer of skin has formed underneath. An older snake may shed its skin only once or twice a year, but a younger, still-growing snake, may shed up to four times a year.

Check the range maps (on snake pages) to determine if the species of snake actually occurs in your area. For each species there is a listing of key characteristics that will help you distinguish the snake from those of similar appearance. Each snake description includes whether the species has keeled or smooth scales.

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