Class: Reptilia (Reptiles)
Crotalus (largest and most widespread)
Species: about 30
Length: Largest—eastern diamondback Crotalus adamanteus at up to 8 feet (2.4 meters); smallest—ridge-nosed rattlesnake Crotalus willardi at 12 inches long (30.5 centimeters). Most species are 24 to 48 inches long (61 to 122 centimeters).
Weight: eastern diamondback—4 to 10 pounds (1.8 to 4.5 kilograms); ridge-nosed rattlesnake—3 to 4 ounces (85 to 113 grams)
Life span: 25 years
Gestation: about 90 days
Number of young: most species give birth to10 to 20 live, fully formed young
Size at birth: 7 to 15 inches (18 to 38 centimeters) long, depending on species
Age of maturity: 18 months to over 2 years
Conservation status: Aruba Island rattlesnake Crotalus unicolor is at critical risk, and many other species are now protected.
Rattlesnakes are also called pit vipers because
they have a heat-sensitive organ known as a "pit" on
each side of the head that helps them locate and aim at prey.
A rattlesnake can detect prey that are as little as 1/10 of a
degree warmer than their background!
Young rattlers leave their mothers at just a few weeks old, but when it’s time to hibernate in the winter, they follow their mother’s scent trail and use the same den. Future generations will also use the same den—some have been used for over 100 years!
The Santa Catalina Island rattlesnake Crotalus catalinensis has no rattle! It’s found only on Santa Catalina Island, off the coast of southern Baja California, Mexico. This snake climbs trees and sneaks up on its bird prey, which is easier without a noisy rattle.
Who would guess that rattlesnakes are good swimmers? They’ve been found several miles out at sea!
The San Diego Zoo was the first facility in the world to hatch the Aruba Island rattlesnake.
Listen to a Mojave rattlesnake!
Rattlesnakes! The word alone fills most people with fear and anxiety because they have no experience in dealing with snakes. Yet we should learn to appreciate the rattlesnake as one of the most efficient and specialized predators on Earth. Many rattlesnakes struggle to survive as humans move in on their habitat. And some people feel that the only good rattlesnake is a dead one! Read on to discover cool stuff about rattlesnakes and why we need them.
New world snakes
Rattlesnakes all come from the Western Hemisphere (mainly North America) and are considered to be the newest or most recently evolved snakes in the world. First, they have either a rattle or a partial rattle made of interlocking rings of keratin (the same material our fingernails are made of). When vibrated, the rattles create a hissing sound that warns off large hoofed animals or predators. Another unique characteristic is the "pit" on each side of the head, a heat-sensitive organ for locating prey.
No eggs laid here!
Rattlesnakes do not lay eggs in nests. They actually give birth to live young. This type of reproduction is known as ovoviviparous. Female rattlesnakes only reproduce once every two years and carry the eggs inside their bodies for about 90 days. Young rattlers are almost independent just minutes after they are born, and in some species their venom is more toxic than the adults’ venom. At one to two weeks, they shed their skin and the first segment of their rattle is created (this happens each time they shed their skin).
out for San Diego
Although California has a number of rattlesnake species, only four species are found in San Diego County. While rattlesnakes locally may be found from the coast to the desert, each species varies in color and behavior with their habitat. The reason for this variation lies in evolution: these four species have evolved to fill different niches in different habitats, which limits competition for food.
Red diamond rattlesnake Crotalus exsul ruber—San Diego’s largest snake species may be found from San Bernardino and Riverside counties down into Baja California, Mexico. They are common in areas with little development, especially near rocky outcroppings. Food consists of anything from small lizards to rabbits and squirrels.
Southern Pacific rattlesnake Crotalus helleri—Also called a western rattlesnake, this is the most common species in San Diego and may be found near housing developments, parks, and even the beach. Its range is from coastal Southern California to northwestern Baja California, Mexico, and they are commonly found on prairies or sage scrub/grassland areas, especially near rocky outcroppings. Like the red diamondback, the southern Pacific rattlesnake feeds mainly on reptiles and mammals, as well as birds.
Southwestern speckled rattlesnake Crotalus mitchelli pyrrhus—This species is the least seen in Southern California because it tends to be shy and avoids populated areas. From the foothills of the Cuyamaca Mountains to the peaks and down into the deserts to the east, their preferred habitat is in granite rocky outcroppings. They can range into southern Nevada, western Arizona, and into northern Baja California.
Colorado desert sidewinder Crotalus cerastes laterorepens—Found only in the desert, this is our smallest species. It grows to just over two feet ( 0.6 meters) as opposed to three or four feet (0.9 to 1.2 meters) in the other three local species. This rattler occurs the farthest south, from southeastern California, southeastern Arizona, and down the east coast of northern Baja.
At dusk, a hungry rattlesnake may begin to move and look for a good spot to ambush a mouse, rat, ground squirrel, or rabbit, its main prey items. Its forked tongue flicks in and out, picking up odor particles from the ground and passing them over a special smelling organ in the roof of the mouth, called the Jacobson’s organ. Then the snake lies in wait until the rat or mouse comes along. Even in total darkness, the rodent will be visible to the snake. This is because the heat-sensitive pits on each side of the snake’s head will detect the heat from the rodent, and nerves transmit this information to the same area in the brain that receives optic nerve impulses. It is accurate to say the rattlesnake "sees" a heat image of its prey, and it can strike in darkness if the prey is even slightly warmer than its background. The rattlesnake's fangs inject venom into its prey. The species and habitat of the snake determines how potent its venom is. After the strike, the snake flicks its forked tongue in and out, picking up odor particles from the ground to help it locate the trail of the dying rodent in the dark.
Rattlesnakes only look for food when they re hungry. An adult rattler goes about two weeks between meals, on average, depending on how large its last meal was. Younger rattlesnakes eat more often, about once a week.
We’re afraid of being bitten, but remember that snakes bite to defend themselves. If frightened, they will first try to escape or hide, so be sure to stay out of their way. Different species will react in different ways: some remain still, depending on their cryptic coloration for camouflage, while others just glide away silently. If this isn’t an option, then they will hiss, rattle their tail, and puff up their body to warn off an enemy. Most snakes will give a warning before they bite, although they may strike quickly if they are startled during shedding, mating, or giving birth. When out walking in heavy brush or rocky areas, watch where you step or put your hands!
Always be alert when out hiking and move away if you see a rattlesnake. Never try to kill a snake: many bites occur when attempting to kill a snake. Snakes should never be killed just because you encounter them on a walk. But if you are bitten by a venomous snake, you must go immediately to a hospital as quickly as possible. Never try "home remedies" (none are effective) and do not ignore the bite. While few snakebites are fatal to people, venomous snakebites should never be left untreated.
Living with rattlers
Using common sense, we can share our open spaces with rattlesnakes. These beautiful animals are important to the environment because they control rodent populations. Let’s protect them and see them as solutions to problems rather than as misunderstood animals we fear and want to eliminate. Just a little care in where we put our feet when we are out hiking is all that is necessary for us to coexist with this fascinating predator.