The eastern diamondback rattlesnake (Crotalus adamanteus) is the heaviest venomous snake in North America. It is easily recognized by the diamond-shaped pattern of scales on its back.
Fast Facts: Eastern Diamondback Rattlesnake
- Scientific Name: Crotalus adamanteus
- Common Names: Eastern diamondback rattlesnake, diamond-back rattlesnake, common rattlesnake
- Basic Animal Group: Reptile
- Size: 3.5-5.5 feet
- Weight: 5.1 pounds
- Lifespan: 10-20 years
- Diet: Carnivore
- Habitat: Coastal southeastern United States
- Population: 100,000
- Conservation Status: Least Concern
The eastern diamondback is a dull blackish gray, brownish gray, or olive green snake with a diamond pattern down its back and black band over its eyes bordered by two white stripes. The diamonds are outlined in black and filled with tan or yellow scales. The underside of the snake is yellow or cream. Rattlesnakes have the pits and head shape characteristic of vipers. The diamondback has vertical pupils and a rattle at the end of its tail. It has the longest fangs of any rattlesnake. A 5-foot snake has fangs measuring two-thirds of an inch.
The diamondback is the largest type of rattlesnake and the heaviest venomous snake. The average adult measures 3.5 to 5.5 feet long and weighs 5.1 pounds. However, adults can get much larger. One specimen killed in 1946 was 7.8 feet long and weighed 34 pounds. Males tend to be larger than females.The snake's rattle tells how many times it has shed, but not its age. douglascraig / Getty Images
Habitat and Distribution
The eastern diamondback is native to the coastal plains of the southeastern United States. Originally, the snake was found in North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, and Louisiana. However, the species is endangered (possibly extirpated) in North Carolina and extirpated in Louisiana. The snake inhabits forests, marshes, swamps, and prairies. It often borrows burrows made by gopher tortoises and gophers.
Eastern diamondback rattlesnakes are carnivores that feed on small mammals, birds, other reptiles, and insects. Prey include rabbits, lizards, squirrels, rats, mice, quail, young turkeys, and any smaller animals when larger targets are unavailable. The snake either waits to ambush prey or else actively forages. A rattlesnake detects food by heat (infrared radiation) and scent. It strikes its target, releases it, and then uses scent to track prey as it dies. The snake can strike at a distance up to two-thirds of its body length. It consumes its meal after it is dead.
Diamondbacks are crepuscular, or active early in the morning and at dusk. The snakes are most comfortable on the ground, but have been known to climb bushes and are excellent swimmers. Diamondback rattlesnakes retreat to burrows, logs, or roots for brumation during cold winters. Large numbers of snakes may gather together at this time.
Like other snakes, the diamondback is not aggressive. However, it can deliver a venomous bite. When threatened, the eastern diamondback raises the front half of its body off the ground and forms an S-shaped coil. The snake may vibrate its tail, causing the rattle segments to sound. However, rattlesnakes sometimes strike silently.
Reproduction and Offspring
Diamondbacks are solitary except during the mating season. Males compete for breeding rights by entwining one another and seeking to throw their competitor to the ground. Mating occurs in late summer and fall, but each female only reproduces once every 2 to 3 years. Gestation lasts six to seven months. All rattlesnakes are ovoviviparous, meaning their eggs hatch inside their body and they give birth to live young. Females seek burrows or hollow logs to give birth to between 6 and 21 young.
Newborn diamondbacks are 12-15 inches long and resemble their parents, except their tails end in smooth buttons rather than rattles. Each time a snake sheds, a section is added to the tail to form a rattle. Shedding is related to prey availability and rattles commonly break, so the number of segments on the rattle is not an indicator of rattlesnake age. Eastern diamondback rattlesnakes can live over 20 years, but very few survive that long. Newborn snakes only stay with their mother a few hours before becoming independent. Young snakes are preyed upon by foxes, raptors, and other snakes, while adults are often killed by humans.
The International Union for Conservation of Nature (IUCN) lists the conservation status of C. adamanteus as "least concern." However, less than 3% of the historical population remains. The estimated population as of 2004 was around 100,000 snakes. The population size is decreasing and the species is under review for inclusion in the U.S. Fish and Wildlife Service Endangered Species List.
Eastern diamondback rattlesnakes face many threats. Their habitat has been degraded and fragmented by urbanization, forestry, fire suppression, and agriculture. Large numbers of the snakes are collected for their skins. Although not aggressive, rattlesnakes are often killed out of fear of their venomous bite.
Eastern Diamondback Rattlesnakes and Humans
Diamondback rattlesnake skin is valued for its beautiful pattern. The species has the reputation as the most dangerous venomous snake in North America, with a bite mortality rate ranging from 10-30% (depending on source). An average bite can deliver 400-450 milligrams of venom, with an estimated human lethal dose of only 100-150 milligrams. The venom contains a compound called crotolase that clots fibrinogen, ultimately reducing platelet count and rupturing red blood cells. Another venom component is a neuropeptide that can cause cardiac arrest. The venom causes bite site bleeding, swelling and discoloration, extreme pain, tissue necrosis, and low blood pressure. Two effective antivenoms have been developed, but one is no longer manufactured.
Rattlesnake first aid steps are to get away from the snake, seek emergency medical assistance, keep the injury below the level of the heart, and remain as calm and still as possible. The prognosis for a rattlesnake bite is good if it is treated within the first 30 minutes. If untreated, a bite can cause organ damage or death within two or three days.
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