Species
    Snakes are believed to have evolved from burrowing lizards. These lizards were long and string-like and lost their legs. It is also believed that the eyes lost all function and became small unusable and covered with a scale. When snakes came to the surface and evolved from these lizards the need for sight arose again. The scale covering the eye became a clear scale known as the spectacle. The spectacle, because it is a true scale, is shed with the rest of the skin during the sloughing process. Also, the internal portions of the eye had to reevolve. This accounts for the differences seen in anatomy of the snakes and lizards.
    There are 18 species of snakes in NY. This is a small percentage of the 2,200 species of snakes worldwide. Snakes, as all animals, have evolved different body plans for different uses. Speciation occurred to allow different snakes to fulfill different niches in the environment. The snakes range from small harmless slug-eating snakes of the genus Storeria through the larger constricting snakes of the genera Elaphe and Lampropeltis to the extremely large and venomous pit vipers. Although the vast majority of snakes are harmless there are three species of venomous snake in othe state.
    Some snakes look superficially like lizards in our area. The presence of legs will differentiate the two. There are no legless lizards in the northeastern United States.
    All snakes are carnivorous, however the preferred food species differs among the species. Common food items for the individual species are listed among the species descriptions.

Terminology

• Coil-
1. the spiral-like way a snake usually sits when it is relaxed or in hiding. Some snakes also use this as a warning posture.
2. a section of snake (also referred to as a loop)
• Loreal Pit- the opening in the face of a pit viper located between the nostril and the eye. This pit is allows the snake to sense differences in heat.
• Rattle Segment- the individual sections that make up a rattlesnake's rattle.
• Scute- the large plate-like scales on the belly
• Striking Coil- the term used for the "S" shaped position a snake often uses to warn of its strike.
• Tail- the tail of a snake is measured as the distance from the vent to the end of the snake.

Movement
    Snake movement has perplexed man for ages. How does an animal without any apparent means of locomotion get from one place to another. There are two primary means of locomotion snakes use. The first is referred to as rectilinear locomotion. The ribs of a snake are connected to the belly scutes by muscle. The ribs move alternately forward and then backward. Not all of the ribs are moving together, however. Some of the ribs are pulling forward while others are pushing backward. The effect is similar to watching a millipede walk. The movement of the ribs pulls the scutes along with them because of the attached muscle. When the rib pulls backward the body is propelled forward through contact with the ground through the scute. This method of locomotion is similar to the movement of a caterpillar and allows the snake to move slowly in a straight line.
    The second primary form of movement in snakes is referred to as serpentine locomotion. The snake throws its body into a series of "S" shaped loops. By contracting the muscles on one side of its body and expanding the muscles on the other side of its body the snake can straighten its body into a line. If the substrate has enough traction the loops will not straighten, but will push on a solid object. This motion creates a force that propels the snake forward. For this method to work the substrate must be solid enough and have enough traction that pressure points are created or the snake will not make any forward motion and will writhe in place. The advantage of serpentine locomotion is that it allows snakes to move quickly, as when escaping danger.
    The third form of movement often mentioned in books but seldom seen is sidewinding. Sidewinding occurs when a snake secures the lower half of its body on the ground, puts the anterior portion of its body in a striking coil-like pose and throws its head and body forward. The middle and tail end of the snake is pulled toward the head and the process begins again. Tracks left by this form of movement are "J" shaped. Although this form of movement is seldom encountered in the field it can sometimes be reproduced by placing a snake on an extensive tract of sandy surface and watching it move. The advantage in sidewinding is that on unstable ground it allows for quick movement.

Feeding
    All snakes are carnivores, eating some kind of animal matter. A snake's most useful sense is its sense of smell.  The organ that is most important for this is the tongue. The tongue of a snake is deeply forked. Much as humans have two ears to discern which direction a sound is coming, the two separate forks of the tongue act as two separate tongues allowing the snake to discern from which direction a particular odor is coming. When a human's ears pick up sound it will be louder (more intense) on one side than the other. Together the two ears, along with the brain, the information on intensity of sound allows the listener to determine exactly where a particular sound is. In the same way, a snake's two tongue forks receive differing intensities of a certain odor allowing it to very precisely determine the direction of the smell in question.
    Close examination of a snake's mouth will reveal a notch in the upper jaw between the nostrils. Through this notch the snake's tongue has its contact with the outside world even when the mouth is closed. When a snake is aroused the tongue is protruded out of the mouth through the notch, waved up and down a number of times, and is then withdrawn. While it is in contact with the air the tongue picks up minute particles from the air which are then brought into the mouth and come into contact with two cavities in the roof of the mouth. The cavities each correspond to a different tip of the split tongue. These cavities lead to a specialized organ called Jacobson's organ. This organ receives the particles picked up in the air and translates them into signals that the brain can understand. In this way a snake can pinpoint the exact location of its prey, a mate, potential danger, etc.
    A snake's sense of sight is often underestimated. It is very keen and is extremely sensitive to movement. As a result, quick movements around snakes should be avoided. Snake's have little in terms of a focusing mechanism and are a bit nearsighted. In locating prey, then, sight is not as important as smell in determining exact distance.
    A third sense that is used by some snakes to find their prey is the ability to sense heat. Pit vipers are the only group in the northeastern United States which have this ability and it is all due to the loreal pit. This is the large pit found between the nostril and the eye. This apparatus allows pit vipers to sense differences in temperatures as small as 1^oC. There is evidence that the nerve signal coming off of the loreal pit is directed to the orbital lobe in the brain. This means that these snakes may actually have the ability to "see" differences in temperature. As can be inferred, adults of the species possessing loreal pits prefer to eat warm-blooded prey.
    How does a snake, having no limbs, obtain its food? Most species simply grab the potential prey item in their jaws, thus immobilizing it, and swallow the food whole, usually alive. This method works best for those species who eat invertebrates who can do little damage to a hungry snake. Many snakes eat rodents which can do a lot of damage because of their long incisor teeth. Black racers get around this problem by pinning the rodent to the ground after getting it in the racers' jaw.
    Another way that rodent eating species obtain their food is by constriction. Constriction is exemplified by the Elaphe and Lampropeltis groups. These snakes grab the prey in their jaws and at the same time wrap their body around the rodent. They throw two or three coils around the animal and squeeze tightly. This forces the air out of the lungs and suffocates the prey. The advantage of this method is that it is quick and humane and the prey is no longer a danger when it is swallowed.
    The last method snakes use to obtain their food is the one that is the most dangerous to humans. That method is usage of venom. Venom is a natural substance that when injected has the effect of killing the animal that is bitten. Snake venom is nothing more than extremely strong enzymes and proteins that dissolve and digest the affected tissue. Venom used to be classified as hemotoxic and neurotoxic depending on whether it had its strongest effect on the muscle tissue or the nervous system, however all snake venoms are both hemotoxic and neurotoxic although to varying degrees.
    It is quite a feat for an animal with no arms or legs to consume its food once it has caught it. Especially considering that snakes can neither chew their food nor rip it into manageable pieces. They must swallow their food whole. In order to do this, snakes have many adaptations in their jaw bones and skull. The skull is flexible, allowing enough stretch to swallow a large prey item. Also, the lower jaw unhinges from the rest of the skull giving a greater circumference of the mouth. In humans the lower jaw is fused into a single working piece. In snakes, however, the lower jaw is made of two separate pieces. During the swallowing process these two bones come apart and allow larger prey to be swallowed.
    The upper jaw is immobile although the bones supporting the teeth can be moved slightly. When the prey is inside of the snake's mouth the upper jaw bone on one side moves forward and pulls that side of the food item in. The other side then undergoes the same motion. This effectively "walks" the food into the mouth. The teeth point backward to grip the prey securely so whatever goes in will not come out.
    It can take quite some time for a snake to completely swallow a large food item. So that the snake does not suffocate, evolution has given snakes the ability to breathe even while swallowing. The trachea (windpipe) in a snake is located far ahead of the gullet and can be seen when a snake's mouth is held open as the moist hole near the front of the lower jaw. This is located far enough ahead that it is exposed while the prey is being swallowed allowing the snake to breathe.

Reproduction
    There are few generalities when it comes to snake reproduction. In most cases snakes mate in the spring after the hibernation period. There is evidence that without the hibernation period reptiles will have decreased fertility. It is believed that snakes find their mates by the use of pheromones, airborne chemicals that are picked up by another individual. These chemicals signal the presence and availability of a mate. Usually it is the males that seek out and travel long distances in order to mate.
There are no characteristics which are shared by all snakes to determine male from female. The one generality that can be seen in the field is that male snakes of most species have longer and thicker tails. This is especially true of certain colubrids. Probing the cloaca for the presence or absence of a hemipenis can be done by experienced individuals, however this can cause trauma to the snake if it is handled roughly.
    Mating is accomplished with the use of a paired hemipenis. (More information on the hemipenis can be found in the section on lizards.) Fertilization is internal in all species of snakes. Parthenogenesis (reproduction without fertilization, in essence, cloning) is rare in snakes but it has been documented in several species, such as the eastern garter snake. One species of snake, the Brahminy blind snake (Ramphotyphlops braminus), is strictly parthenogenic. Females can also store sperm for several years. This allows for reproduction in years in which no mating occured.
    Many species of snakes lay eggs. This is referred to as oviparity. Of the 24 species and subspecies in the range covered, 10 are oviparous. Inside of the mother's body, the embryo and yolk is surrounded with embryonic fluid, the amniotic sac, and a calcium rich shell. Shells of snakes are not hard and ungiving like a chicken egg, but are soft, leathery, and pliable. The female carrying the eggs will enter a shed cycle two to three weeks before laying the eggs. This is referred to as the pre-egg laying shed. The eggs are laid in a moist, warm area that is sheltered from the elements. This occurs in late spring. Few snakes actually build nests and none are documented in this area. In late summer to early fall the young snakes use their egg tooth to cut out of the egg. They hatch as miniature replicas of the adults and disperse on their own.
    Not all snakes leave their eggs to be cared for by the elements. Most of the snakes in this area (14 of 24) are ovoviviparous, meaning they retain the eggs inside of the body until it is time for the eggs to hatch. There is no calcified shell and the young snakes must only break through the relatively weak amniotic sac. Because all development occurs inside of the female's body and she controls the temperature, fewer harmful mutations due to temperature occur and the overall success rate is higher than would be if the snakes were to lay eggs.
    Because the young snakes (termed neonates) are little copies of the adult snake they require no parental care. The first order of business for a young snake is to find somewhere to hide. The small size of the neonates make them easy prey to all sorts of predators. A hiding place makes this less likely. One to two weeks after hatching the neonates undergo the post-natal shed. It is after this first shed that the snake will have its first meal. Soon after, it enters hibernation. If the snake was born late in the year it will enter hibernation without eating.

Families
Snakes are in the Class Reptilia, Order Squamata, Suborder Serpentes. There are 18 species of snakes in our range representing two families.

Family Colubridae- Common Snakes

• Eastern Worm Snake- Carphophis amoenus amoenus
• Northern Black Racer- Coluber constrictor constrictor
• Northern Ringneck Snake- Diadophis punctatus edwardsii
• Black Rat Snake- Elaphe obsoleta obsoleta
• Eastern Hognose Snake- Heterodon platirhinos
• Eastern Milksnake- Lampropeltis triangulum triangulum
• Northern Water Snake- Nerodia sipedon sipedon
• Smooth Green Snake- Opheodrys vernalis
• Queen Snake- Regina septemvittata
• Northern Brown Snake- Storeria dekayi dekayi
• Northern Redbelly Snake- Storeria occipitomaculata occipitomaculata
• Shorthead Garter Snake- Thamnophis brachystoma
• Eastern Ribbon Snake- Thamnophis sauritus sauritus
• Northern Ribbon Snake- Thamnophis sauritus septentrionalis
• Eastern Garter Snake- Thamnophis sirtalis sirtalis

Family Viperidae, Subfamily Crotalinae (Pit vipers)

• Northern Copperhead- Agkistrodon contortrix mokasen
• Timber Rattlesnake- Crotalus horridus
• Eastern Massasauga- Sistrurus catenatus catenatus