6 venomous species (18% of total) in California, all rattlesnakes
8,000 cases of envenomation per year in North America, only 10-15 fatalities
in many snakes the left lung is reduced or absent
some snakes lay eggs and others give birth to live young
rattlesnakes give birth to live young
venom is a prey immobilization adaptation in snakes, defense is secondary
venom is 90% protein
venom is composed of neurotoxins (attack nervous system) and/or hemotoxins (attack circulatory system)
neurotoxins in gila monsters, coral snakes (not in CA), Mojave rattlers
snakes can meter dosage of venom to prey
The southern Pacific rattlesnake (Crotalus viridis helleri) is frequently found in coastal and mountain habitats in southern California. Other forms of this species range from Canada to Mexico and to western Iowa. Photo by Kathie Meyer.
Venom facts for rattlesnakes found in California
Sidewinder -- Venom is of moderate toxicity. Human lethal dose is 40 mg and people have died from envenomation. Average venom delivered per bite is 20-63 mg. Venom is still lethal to mice and cats after 27 years of storage. Venom causes deep tissue necrosis at site of bite.
Speckled rattlesnake -- Venom is very potent. Minimum lethal dosage for 350 gram pigeon is 0.002-0.04 mg, for mice 0.05-0.12 mg. Adults contain up to 227 mg of venom (dry weight) but inject 0.16 mg. Dried venom potency undiminished after 27 years storage.
Red diamond rattlesnake -- Long fangs (over 1/2 inch). Low in toxicity compared to other rattlesnakes but this is a large species capable of delivering large amounts of venom. Lethal dose for people is about 100 mg and 150-350 mg (up to 1.65 ml) is delivered per bite. People have died from envenomation. Lethality of venom decreases only slightly after 27 years, producing complete neuromuscular block of a cat diaphragm in 22 minutes. Tissue damaging properties of venom are 6-15 times greater in adults than juveniles. In one case history an adult man spent 9 days in the hospital (antivenom was administered) following a bite to the leg and was able to walk almost normally in two weeks.
Southern Pacific rattlesnake (western rattlesnake) -- Venom primarily hemorrhagic (affecting blood) but some subspecies contain neurotoxic components. Toxicity of venom is greater than some larger species such as the western diamondback. This coupled with the high irritability of some individuals makes this a dangerous snake. Hemorrhagic, neurologic and proteolytic activity can all result from the same bite. Hemorrhagic activity in 18 minutes accompanied by some paralysis. Death in untreated cases may occur in 18 hours or up to 5 days. Lethal venom dose for humans is 70-160 mg and adults can produce up to 112 mg of venom (dried). Dried venom toxic to mice for at least 27 years.
Western diamond back rattlesnake -- Fangs over 1/2 inch in length. Venom highly hemorrhagic. 53% of the enzymes cause breakdown of the circulatory system, 17% are neurotoxic, and 30% digest proteins. Hemorrhaging from vascular breakdown occurs in only 6 minutes. Stored venom loses little potency after 17 years. Lethal dose to humans is about 100 mg and snakes may contain up to 300 mg (dried). One snake yielded 1,145 mg (3.9 ml liquid)! This species probably responsible for more human deaths than any other snake in the U.S. Symptoms following bites include intense burning, vomiting, breathing difficulties, lowered blood pressure, increased heart rate, and secondary gangrene infection.
Mojave rattlesnake -- Neurotoxic venom is extremely virulent (10 times more toxic than any other rattlesnake in the U.S.) affecting heart, skeletal muscles and neuromuscular junctions. Once bite sufficient to kill a human: lethal dose is only 10-15 mg and one adult can yield 141 mg (dried). Death occurs in a high frequency of untreated cases.
Snakes: Facts You May Not Know
1. Most snakes are harmful . False : Most snakes are harmless
2. Snakes can’t smell with their nose . False : They smell with their noses , but the tongue and Jacobson’s organ (an indentation on the roof of their mouth with many nerve endings) are more important to them.
3. Snakes feel slimy . False : Touch one . It’s usually warm and dry.
4. The purpose of scales is to keep snakes warm . False : Scales are watertight . The main purpose is to keep moisture in , so the snake won’t dry out in the heat.
5. Snakes can hypnotize people and animal . False : The myth probably arose because of the way snakes stare without moving , and many animals freeze when a snake stares at them
6. Snake scales are heavy . False : They’re actually as this as paper.
7. Snakes are cold . False : Some snakes can maintain body temperatures of over 100 degrees-higher than humans (who can create their own body heat).
8. Snakes are aggressive and strike whenever possible . False : Most snakes are cowards that prefer to swish away and avoid fight.
9. Snakes don’t have backbones . False : Snakes sometimes have as many as 300 vertebrae-compared to a person who has only 33 or 34.
Cool Snake Facts
Snakes are cold-blooded animals. This means that a snake's body temperature is about the same as the temperature of their surroundings. When the temperature warms up they become more active and when it gets colder they are less active. If it is too cold they are not active at all. Warm blooded animals have a constant body temperature. Humans are warm blooded animals and maintain a constant body temperature of about 98.6 degrees Fahrenheit.
Brown snakes rarely bite but, like most snakes, brown snakes will release a bad odor when frightened.
Brown snakes are awake during the day in the fall and spring, but in the summer they are awake at night.
The brown snake grows to be about 9 – 13 inches long.
Brown snakes are not poisonous.
The brown snake gives birth to live young.
All snakes shed their skin.
The Basics
Easier - Snakes are long, thin reptiles. They do not have legs and they slither along the ground. In the United States, only copperheads, coral snakes, rattlesnakes, and water moccasins have poisonous bites.
Harder - Snakes have a long, legless, flexible body that is covered with dry scales. When snakes move about on land, they usually slide on their belly. Snake's eyes are covered by clear scales rather than movable eyelids; therefore, their eyes are always open. They repeatedly flick out their narrow, forked tongue, using it to bring odors to a special sense organ in the mouth.
Snakes belong to the order of animals called reptiles. This group also include crocodiles, lizards, and turtles. As with the other reptiles, snakes maintain a fairly steady body temperature by their behavior. They raise their temperature by lying in the sun or lower it by crawling into the shade.
There are about 2,400 species of snakes in the world. They live almost everywhere, in deserts, forests, oceans, streams, and lakes. Some are ground dwellers, others live in trees, and other snakes spend most of their lives in water. There are a few areas where snakes do not live. They cannot survive in places where the ground stays frozen the year around, so they are missing in the polar regions or at high mountain elevations. Several islands, including Ireland and New Zealand, do not have snakes.
You can use this guide in several ways. If you are trying to identify a snake you have seen (or are seeing), go through our series of questions to identify the snake. If you know the name of the snake you want to find information on, click on the name of the snake. If you want general information on snakes go to 'Information on Snakes.'
Snakes are an intriguing group of animals. Often misunderstood, they are an integral part of many natural habitats. Knowing more about them can help us enjoy the outdoors and appreciate the many different kinds of wildlife that surround us. This publication is intended to help people identify the snakes of Indiana, increase the awareness of snake conservation and biology, and correct many misconceptions about snakes.
These web pages are based on the publication "Snakes of Indiana" authored by Brian MacGowan and Bruce Kingsbury, cooperatively produced by Purdue University, Indiana-Purdue University, Fort Wayne, and the Indiana Department of Natural Resources, Division of Fish and Wildlife. If you would like a copy of the booklet, you can obtain one for .50 (check, money order, or Visa/MasterCard- includes tax and shipping) from the DNR using the following contact information:
Snakes are reptiles, a class of vertebrates that also includes lizards, turtles, crocodiles and the tuatara, a small group of lizard-like animals found in New Zealand. As a group, reptiles share many common characteristics. All reptiles have scales. They grow by literally “crawling out of their skin” two to four times annually- they must regularly shed the outside layer of their skin as they get bigger. Reptiles have a body temperature that is the same as their surroundings. They regulate their body temperature by basking in the sun when cold, or seeking shade and reducing activity when warm. Therefore, ambient temperature influences the daily activities of all snakes. For example, snakes tend to be more active during the middle of the day in the spring and fall when evenings are cool, and more active in the morning and evening during the hot summer months.
What makes a snake a snake? Snakes lack legs, unlike most other reptiles. However, boas have tiny spurs that are remnants of hind limbs, and a few other reptiles, such as worm and glass lizards, also lack limbs. Snakes move by pushing against objects with specialized scales on their bellies called scutes. The scutes act like tire treads, gripping the ground and giving the snake the traction necessary to push itself forward. Also, scutes are hard and protect the snake as it moves along rough surfaces. The scales covering the body prevent excessive dehydration by retaining body moisture and contain pigments that form the color patterns of snakes. Snakes have no moveable eyelids, and therefore can never blink or close their eyes. A single transparent scale covers the eye. They do not have external ears, but can hear by sensing vibrations through the bones in their head. In addition to being able to smell odors as we do, snakes can “taste” the air and ground using their forked tongue. Particles picked up by the tongue are processed by the Jacobson’s Organ in the roof of the mouth.
Most snakes mate in the spring after they emerge from hibernation. Depending upon the species, snakes can reproduce by either laying their eggs (oviparous) or by hatching the eggs internally and bearing live young (ovoviviparous). Some oviparous species in the state are kingsnakes, Black Rat Snakes, bullsnakes, racers, worm snakes, and green snakes. Snake eggs have a tough, leathery shell. Females lay their eggs in rotten logs or leaf litter. The eggs usually hatch in later summer to early fall. Water snakes, garter snakes, brown snakes, copperheads, cottonmouths and rattlesnakes all examples of ovoviviparous species in Indiana. The young of these snakes develop within the female in a sac-like membrane that contains yolk for nourishment. Some snakes break through this membrane before being born while others break through after their birth.
All snakes are carnivores, preying upon a variety of different animals including other snakes, fish, frogs, salamanders, rodents, insects, birds and slugs. Snakes have no claws or chewing teeth – they must eat their prey whole. They are able to eat prey larger than their head by allowing their jaws to disarticulate while swallowing and subsequently rearticulating the jaw when finished. Some snakes actively pursue their prey while others remain motionless and well camouflaged, waiting for unsuspecting prey to wander within striking distance. Snakes’ diets vary among species and depend upon their size and behavior. For example, small snakes typically prey upon small, slow-moving animals like slugs and earthworms. Larger snakes often prey upon larger, more active prey. Snakes lack chewing teeth, and therefore, must eat their prey whole. Also, snakes lack appendages to grip and hold prey. As a result, many species have developed intriguing methods for capturing, immobilizing and killing their prey. Some snakes are able to kill their prey by constriction, thereby suffocating their victim, while others make use of venom that immobilizes their prey.
Snakes have evolved a variety of defense strategies since they are preyed upon by mammals, birds, and even other snakes. Camouflage coloration may conceal a snake’s shape and confuse predators. When threatened, some snakes become immobile or “freeze” when they sense danger. Since many predators (hawks, owls, etc.) hunt by visual cues, they do not notice the motionless snake. Snakes also often employ a variety of bluffing behaviors. Several species vibrate their tail when threatened, making a rattling sound when it strikes dry leaves. Believing the snake to be a venomous rattlesnake, the predator may move on, unwilling to risk a potentially dangerous encounter. The eastern hog-nosed snake makes itself appear larger and more threatening by flattening its neck, and hissing loudly. If this does not work, these snakes will even play dead by lying on their backs and discharging a foul smell from specialized glands.
Venomous vs. Nonvenomous Snakes in Indiana
When someone encounters a snake, the first question that comes to mind for some is whether or not the snake is venomous. Most of Indiana’s snakes are not poisonous. In fact, there are only four venomous snakes in the state, and their distributions are limited (check the maps in the back of this booklet). All of the venomous snakes in Indiana belong to the pit viper family. Members of this family share common physical characteristics that separate them from nonvenomous species. Pit vipers have a sensory pit located between the eye and the nostril on each side of their head. These pits detect heat, thereby helping the snake locate warm-blooded prey, even in the dark. Other snakes lack these sensory pits. Thus, if it looks like your snake has four nostrils, it’s a pit viper. Of course, checking for pits requires getting a good look at the “business” end of the snake – to be safe, don’t get closer than the length of the snake. This brings up a general point: no one should ever attempt to handle a snake that is or may be venomous unless they have undergone extensive training by a professional. Even snake researchers avoid handling their venomous subjects whenever possible.
Because there are so few poisonous snakes in Indiana, we can impose some simple rules to help you to identify them. These rules will not work outside of this state or with exotic species. Indiana’s poisonous snakes are all very heavy-bodied – they look “fat.” They also have broad, spade-shaped heads that are distinctly wider than their narrow necks. The heads of nonvenomous snakes are typically about the same width as their bodies. Such distinctions are not completely reliable, as some species such as water snakes can be rather stout, and many species of snakes will flatten their heads when bluffing, giving the head a spade-like shape as well. Thus, having had a good meal should not be a death sentence for snake (but then, neither should being venomous!). The pupils of the venomous snakes of Indiana are vertical slits rather than round. This distinction may not hold elsewhere, but works in this state.
Do not attempt to handle or kill a snake that you believe may be venomous. Simply keep at a safe distance and move on your way. Snakes do not actively seek out people and bite them. Given the chance, snakes will almost always try to escape an encounter. If you leave them alone, they will make every effort to leave you alone as well. Be very careful to avoid the head when handling dead snakes. A snake’s reflexes can remain functional hours after death, and supposedly “dead” snakes have bitten people.
Perhaps the last point to emphasize regarding Indiana’s poisonous snakes is that most have limited distributions. This fact is discussed in detail in the species accounts later, but consider the following points. First, there is only one poisonous snake (the Eastern Massasauga Rattlesnake) in all of northern Indiana, and it is rare and lives in types of wetlands where people rarely go. Only a few are seen each year. The cottonmouth is restricted to a single small wetland in the southernmost part of the state. They are almost never seen in Indiana, even by specialists who know exactly where they should be. Thus, those water snakes people see while fishing around the state are simply common water snakes – they are not venomous. Timber Rattlesnakes are also rare, restricted to some of the forested hills in south-central Indiana. The most common venomous species is the Northern Copperhead, and even it has a restricted range in the hills of southern Indiana.
Venomous Snakes and Snake Bite
Although thousands of persons are bitten by venomous snakes every year throughout the United States, such bites in Indiana are very rare. Most bites occur when people are trying to kill or handle snakes. Snakes will always flee an area rather than strike, unless they are harassed or startled. While the bite of a poisonous snake is dangerous, it is rarely fatal - more people die from bee stings and lightening strikes annually. Nevertheless, immediate medical help should be sought in case a bite occurs.
Things you can do to prevent being bitten by a snake:
· If you know you will be in areas known to have venomous snakes, wear high-topped, leather hiking boots.
· Do not reach under rocks or logs, and do not step over logs. Step on them, then over.
· Be alert and search the area ahead of you. Do not merely look down at your feet. Be wary of areas containing logs or rocks. Remember that many venomous snakes blend in with their surroundings and may be difficult to see unless you are alert.
What if you are bitten?
In the event of a venomous snakebite, seek medical attention IMMEDIATELY. While it is helpful to identify the snake, do not waste time or risk being bitten again by capturing or killing the snake. The most important things to do if bitten are to stay calm and avoid excessive activity, and seek medical care as soon as possible. Do not make any incisions at the bite. Nonvenomous snakebites should be washed with soap and water to reduce the risk of infection. For the latest information on snakebite first aid, contact your nearest American Red Cross office or ask your physician.
Snake Conservation
Snakes have been declining in numbers throughout the state for many reasons. The primary reason for this is probably habitat loss. The development of wetlands and other critical habitats for human use has had a severe impact on the populations of snakes and other animals in the state. In addition, collection of snakes by hobbyists and reptile dealers has greatly contributed to their decline in the wild. Another contributing factor has been pesticide use. The overuse of pesticides has been detrimental to snakes that eat large quantities of insects and spiders. Finally, some snakes in Indiana were less common to begin with because Indiana represented the farthest extent of their range. Typically, species on the periphery of their range respond more strongly to fluctuations in numbers due to changes in environmental influences such as weather. However, these natural shifts in populations can be elevated by negative factors such as habitat loss and collection.
Like many other states, Indiana is making an effort to protect its reptiles and amphibians (herpetofauna). Thus the collection and possession of herpetofauna in the state requires a hunting or fishing license for all persons 17 years or older (unless you are collecting on your own farm). Bag limits and seasons are in place to regulate the number of reptiles and amphibians collected each year. Typically, in the case of animals such as snakes, the limit is four. These regulations were established due to the drastic declines in populations of snakes and other herpetofauna throughout the state. Without protection, these species would continue to decline. Endangered species may not be collected or possessed without special permits. There are additional requirements for dangerous species, or for having extra animals for breeding or conducting research. If you have any questions regarding the collection of snakes and other reptiles and amphibians, contact the Indiana Department of Natural Resources, Division of Fish and Wildlife at (317) 232-4080 or your local Conservation Officer.
There are many reasons for protecting snakes. They play an important role in controlling many yard and garden pests. Also, snake venom has been used in the development of many human medicines for blood and heart problems. Regardless of their direct benefits to us, all snakes have an important role in nature. They are a link in the chain of life and if one link is destroyed, the whole system may weaken and be jeopardized.
Snakes - 20 Facts
Below are some interesting facts that you may or may not have known about snakes:
Geographic location forced snakes to evolve and change on their own
It is thought that snakes evolved from lizards
Snakes live in oceans, trees and on the land
Snakes are both predators and prey
¼ of all snakes have venomous fang
70% of all snakes hatch from eggs
Snakes vary greatly in size and weight, although they have the same basic body structure
Snakes have no limbs
The King Cobra is the largest of all venomous snakes, and actually eats other snakes
Snakes taste odours in the air with their tongues
When snakes strike they have a near 100% success rate
Snakes can expand the capacity of their jaws due to an elastic jaw ligament
Snakes have poor eyesight, and so have heat censors that can pick up vibrations
Snakes can tell the difference between temperature changes and body heat from prey using these censors
Night snakes contract their iris to a slit during light, due to light sensitivity
The eye of the snake goes milky just before they shed their skin
Once the skin is shed the snakes' skin doesn't actually have a colour
There are seven families of snake throughout Australia
The most common snake family in Australia is the Elapidae
The most deadly snakes found in Australia include Brown Snakes, Copperheads, Death Adders, Red-Bellied Black Snakes, Taipan Snakes and Tiger Snakes
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In Texas, you're four times more likely to be killed by lightning than a snakebite. We have an average of two to three deaths per year from snakebites, compared with five to seven for insect bites and eight from lightning.
Snakes range farther north and occur at higher elevations than lizards. They are also adapted to a much wider range of environmental conditions.
There are no snakes in Ireland, Newfoundland, New Zealand or many South Sea islands.
Contrary to popular belief, snake skin is not clammy or slimy, but smooth, dry, and slightly cool to the touch.
In Australia, the majority of snakes are venomous, approximately 80%. You need to watch where you step down under.
Rattlesnakes can't hear the sound of their own rattles.
Large prey and a slow metabolism give snakes the advantage of not having to eat so often. Few eat more than once a week; many eat from 8 to 10 times a year. Some are capable of very long fasts.
Numerous species of snakes occasionally or regularly eat snakes of other species, usually much smaller than themselves.
(A) The rattlesnake tail is made up of a series of loosely linked, interlocking chambers that when shaken, vibrate against one another to create the warning signal of a rattlesnake. Only the bottom button is firmly attached to the tip of the tail. (B) Scales on the underside of the snake (venter scales) provide the contact edges essential for the snake to move. At the end of the venter scales is an anal plate which protects the opening to the cloaca. The cloaca is a shared opening for waste and reproductive material to pass. (C) Snakes have dry keratinous scales. The size, arrangement, and number varies by species and location on the body. Generally, scales on the head are larger on top, smaller and more numerous on the sides and around the mouth and chin. (D) Body scales usually lie in linear rows with each having a fixed number of scales, typically an odd number ranging from 13 to 27. This number is species specific. (E) The body of the snake contains a string of vertebrae (bones that make up the spine). Typically, there are more than 120 in the body and tail and in some species as many as 585.
In vipers, (1) the hinged fangs are located on a shortened bone (maxilla) that can rotate forward and backward. When not in use, the fangs fold backward against the roof of the mouth, where they are in a protective sheath. (2) In most venomous snakes, the delivery of venom is much like a hyperdermic needle. When the victim is first bitten with the fangs, muscles on the venom gland are compressed forcing the venom through the venom duct into the venom inlet on the fang, through the venom canal, and exiting the outlet channel into the wound. (3) Pit organs, present in boas, pythons, and pit vipers (which includes rattlesnakes) can sense infrared heat radiated from an object. Basically, this vision detects a temperature difference in an object and its surroundings. This is ideal for hunting warm-blooded mammals and birds at night.
How Snakes Move A snake's flexibility depends upon its many muscles. Snakes have long chains of muscles along the vertebrae, connecting the vertebra, from rib to rib, and from rib to vertebrae. Their skin muscles allow the ribs to pull scales forward and backward, which help the snake to move. Snakes are incapable of significantly lengthening and shortening their total body length because they do not have a hydrostatic skeleton. They get the same effect by throwing their bodies into coils. The wider the coils, the faster they move.
Sidewinding: Many snakes in hot deserts and on shifting surfaces like sand move by "sidewinding." In this kind of movement the main thrust is sideways rather than backwards. Only three parts of a sidewinder's body are in contact with the ground at any one time. This prevents the snake's belly from resting on the desert sand long enough to become painfully hot. Sidewinding snakes will leave an "S" trail in the sand. Concertina Movement: A "concertina" movement is used in narrow tunnels or burrows. In this movement the snake wedges his coils against the sides of the tunnel and extends the rest of his body.
Caterpillar Movement: Large boas, pythons, and vipers use this type of movement because their weight gives them a better grip on the ground. Snakes who use the caterpillar movement keep their bodies in a fairly straight position while successive groups of belly scales are erected, angled forward, then pressed back against the ground. This functions as a lever to move the snake smoothly along.
What makes a snake a snake? Snakes lack legs, unlike most other reptiles. However, boas have tiny spurs that are remnants of hind limbs, and a few other reptiles, such as worm and glass lizards, also lack limbs. Snakes move by pushing against objects with specialized scales on their bellies called scutes. The scutes act like tire treads, gripping the ground and giving the snake the traction necessary to push itself forward. Also, scutes are hard and protect the snake as it moves along rough surfaces. The scales covering the body prevent excessive dehydration by retaining body moisture and contain pigments that form the color patterns of snakes. Snakes have no moveable eyelids, and therefore can never blink or close their eyes. A single transparent scale covers the eye. They do not have external ears, but can hear by sensing vibrations through the bones in their head. In addition to being able to smell odors as we do, snakes can “taste” the air and ground using their forked tongue. Particles picked up by the tongue are processed by the Jacobson’s Organ in the roof of the mouth.
Although thousands of persons are bitten by venomous snakes every year throughout the United States, such bites in Indiana are very rare. Most bites occur when people are trying to kill or handle snakes. Snakes will always flee an area rather than strike, unless they are harassed or startled. While the bite of a poisonous snake is dangerous, it is rarely fatal - more people die from bee stings and lightening strikes annually. Nevertheless, immediate medical help should be sought in case a bite occurs. 
Like many other states, Indiana is making an effort to protect its reptiles and amphibians (herpetofauna). Thus the collection and possession of herpetofauna in the state requires a hunting or fishing license for all persons 17 years or older (unless you are collecting on your own farm). Bag limits and seasons are in place to regulate the number of reptiles and amphibians collected each year. Typically, in the case of animals such as snakes, the limit is four. These regulations were established due to the drastic declines in populations of snakes and other herpetofauna throughout the state. Without protection, these species would continue to decline. Endangered species may not be collected or possessed without special permits. There are additional requirements for dangerous species, or for having extra animals for breeding or conducting research. If you have any questions regarding the collection of snakes and other reptiles and amphibians, contact the Indiana Department of Natural Resources, Division of Fish and Wildlife at (317) 232-4080 or your local Conservation Officer.
