Rattlesnake, Eastern Diamondback


Crotalus adamanteus


Maximum length is over 8 feet, but the average is 4 feet. Fangs are ¾ of an inch. Its diamond shaped coloration pattern, dark brown or black, identifies it. The “diamonds” are strongly outlined by a row of cream-colored or yellowish scales. The side of the head is patterned with two white oblique stripes. The ground color of the body is brownish. The tail ends in a rattle. The tail is usually a different shade, brownish or gray, and toward the end of the tail the diamonds fade or break into bands. The pupil is vertical (cat-like), and there is a deep facial pit between the nostril and the eye. The young are similar to the adults in color pattern. The tip of the tail of newborn diamondbacks ends in a ‘button,’ which is the first segment of the future rattle.

Family

Viperidae

Order

Squamata

Class

Reptilia

Range

Southeastern United States

Habitat

Warm coastal lowlands; in Florida, these habitats contain palmetto thickets and gopher tortoise burrows in which this snake may seek refuge. Occasionally it ventures into salt water, swimming to the outlying Keys off the Florida coast

Life Expectancy

10 - 20 years

Sexual Maturity

Probably at 18 months

Diet

In the wild, they eat rabbits, rodents, and birds. In the Zoo, they are fed rats.

Status

IUCN - Least Concern

Behaviors

Individual dispositions vary. Some snakes will permit close approach with out making a sound, whereas others, completely concealed, will rattle when dogs or persons are 20 or 30 feet away. Many stand their ground, but when hard pressed they back away, rattling vigorously but still facing the intruder. Frequently they take refuge in burrows of mammals as well as holes beneath stumps, etc. The rattle is used to warn predators. A male finds a female through scent. Females give birth to 7 to 12 live-born young and may provide some protective care for up to 14 days.

Adaptions

The triangular shaped head with loosely connected jawbones enables the snake to swallow prey larger than its head. Heat sensing pit on each side of head helps the snake to find prey. The tongue is forked and is used to pick up chemicals from the air and place them on Jacobson’s Organ, a sense organ involved in taste and smell. The segmented rattle on the tail grows one additional segment whenever the snake sheds its skin. The pupil is vertical (cat-like). There is a deep facial pit between the nostril and the eye. The facial pit is a sense organ that detects infrared heat, such as body heat. This enables the snake to locate its warm-blooded prey even in the dark. Nature has given the pit vipers an unlimited supply of fangs. Concealed in the roof of their mouth behind each maxillary bone is a series of replacement fangs in progressive stages of development. Throughout the snake’s life there is a never-ending cycle of fangs being created, growing and moving forward. Each one eventually becomes the functional fang of the moment. This shedding of an old fang and replacement with a new fang takes place approximately every 60 to 90 days. Each functional fang is stabilized in position by its attachment to the maxillary bone. Each maxillary bone has two sockets for receiving and holding fangs. Normally only one fang is “glued” in position, but when a new fang is moving into its socket it is not unusual to find the old fang remaining alongside the new one for several days. Rattlesnakes can strike up to 2/3’s of their body length; a 6-foot specimen may strike 4 feet. When not in use a pit viper’s fangs lie folded back against the roof of the snake’s mouth, each resting in a sheath of soft membranous skin. When the moment arrives to bite, the maxillary bones rotate the fangs forward. The venom ducts that lead from the venom glands empty into the sheaths. The venom is forced into the opening at the top of each fang and is squirted out of the opening near the tip of the fang.

Special Interests

The venom is extremely potent and hemotoxic. It is also prey specific. The venom is used to kill the snake’s habitual prey, cotton-tailed rabbits, rapidly. Larger quantities of venom are required for killing a rat, a prey smaller than the rabbit. This snake is the most dangerous in North America and one of the longest at 8 feet. A rattlesnake’s age cannot be determined by counting the number of rattles on its tail. As the young snake grows, it sheds its skin, usually several times a year. Each shed adds a new, loosely overlapped and interlocked segment to the rattle. Shedding twice a year will add two segments to the rattle. Shedding three times a year will add three segments to the rattle. The more a rattlesnake sheds, the more segments are added to its rattle. The tissue that makes up the rattle is rather like a thin brittle fingernail. Just as a human can tear a fingernail, some segments may break off and be lost especially if the rattle should reach a length of between 8 to 10 inches. If the string of rattle segments ends in a smooth rounded button, all the segments are there, and the rattle is complete. If the rattle string ends in a square or tiered nub, the rattle has been broken, and some segments have been lost. These phases of growth and breakage make it impossible to tell a rattlesnake’s age by counting the segments on its rattle. The heat sensing pits located in front of the eyes are used to detect warm-blooded prey. A blindfolded diamondback can still strike accurately at its target, guided by the remarkable sensitivity of these organs. The impulse to strike is so instinctual in the nervous system that this response may remain active for some time after the snake is apparently dead. This action even includes the injection of venom. Simply touching a “dead” snake may trigger the impulse, so be wary about approaching or handling any recently deceased snake. Humans are not the only species killing rattlesnakes. Deer are known to stomp rattlesnakes with their hooves. Sheep and horses are capable of the same thing. Alligators have been seen killing and swallowing large diamondbacks. Bald eagles and red-tailed hawks sometimes attack rattlesnakes, although the outcome of these confrontations is not always predictable. Kingsnakes kill rattlesnakes readily (hence their name “king of the snakes”).

Folklore

Some people wrongly believe the diamondback will always rattle before striking. This is not true. It can lie silent and motionless, and then strike without the usual nervous buzz from its rattle. Some diamondbacks will wait until the intruder is nearly upon it before it rattles. Others will rattle when an intruder is 30 feet away. In fact, diamondbacks that rattle are more apt to be heard, seen and killed than those that remain silent. These “silent” rattlesnakes are more apt to go undiscovered and pass on their genes to the next generation. In this way, humans are inadvertently selecting for rattlesnakes that do not rattle. Early American settlers chose the rattlesnake as their emblem in the Revolutionary War. Flags with the motto “Don’t Tread on Me” showed the rattlesnake with thirteen rattles to represent the thirteen colonies. The rattlesnake was chosen because its bright, lidless eyes represent vigilance, and while it does not seek to attack, it is fearless once it has been attacked. According to Native American superstition, if one dreamed of being bitten by a rattlesnake, one was treated as if actually bitten, from the belief that the body would respond physically to the dream, perhaps even years later. According to Cherokee myth, the rattlesnake was once a man but was changed into a snake and given rattles when it saved the human race from being burnt up by the sun. The Cherokee gave him a name that translates “he has a bell,” in obvious reference to the rattle. Also called “Thunder’s necklace,” the rattlesnake was thought to be the most prized ornament of the thunder god. Cherokees never killed the rattlesnake unless absolutely necessary, and if forced to do this, would plead pardon from the snake’s ghost. The shaman of the tribe revered all parts of the snake –rattle, skin, teeth, flesh, and oil. According to legend, the rattlesnake was originally very timid and harmless and greatly abused by other animals. Rabbit, in particular, picked on Rattlesnake, teasing him, tying him in knots, and throwing him around the campfire. One day the Sun God felt sorry for Rattlesnake and gave him venom and powerful jaws but told him he must always rattle first. The next night when Rabbit began pestering Rattlesnake again, the snake rattled and bit Rabbit. Since that time, the rattlesnake has been greatly feared.

Conservation

Not formally listed, the eastern diamondback rattlesnake is considered endangered in North and South Carolina. Its numbers have been reduced considerably by hunting and habitat destruction due to development. Its rapid disappearance is due, in part, to suburban housing, agricultural development, and “rattlesnake round-ups.” Rattlesnake round-ups are carnival-like events still staged in many parts of our country. San Antonio, a small town near Dade City in Pasco County, has been the site for Florida’s annual rattlesnake round up. In the 1950’s and ‘60’s, events included prizes for the largest, smallest and heaviest rattlers, the pitting of rattlesnakes against kingsnakes, sale of rattlesnake meat, and gopher tortoise races. One colorful character would show up every year with a well-concealed wooden leg and walk dangerously close to big rattlers. The wooden leg, having no body heat, would not tempt the rattlers to strike. Today, the events are mostly educational. To “round-up” the rattlesnakes for these events, people would pour gasoline into the winter burrows, gopher tortoise burrows, of the rattlesnakes. The fumes caused the snakes to flee, and they would be caught upon emerging from the burrow. Since these “gopher holes” are used by a variety of species as shelter, this practice not only upset nature’s balance by eradicating rattlesnakes from an area, but it also destroyed important habitat. This practice is now outlawed in the State of Florida. This snake is extremely beneficial to man because it preys on rats, mice, rabbits, and other warm-blooded prey, many of which are considered pests. Nevertheless, many Floridians feel so threatened by the rattlesnake that most are killed on sight. This indiscriminate killing, combined with the widespread loss of habitat has caused a decline in most diamondback rattlesnake populations. Though not endangered, the species clearly is in trouble. In an effort to educate Floridians about the need to conserve this largest of all rattlesnakes, a Rattlesnake Conservation Committee has been established by the Gopher Tortoise Council.

Jacksonville Zoo History

This species is found in the Zoo’s animal collection in March 1957, but almost certainly goes back to 1915 with the “unnamed rattlesnakes” of those days.

Exhibit

Wild Florida