Species Profile: The Eastern Diamondback Rattlesnake
The eastern diamondback rattlesnake is perhaps the most commonly recognized rattlesnake, thanks to the black diamonds that pattern their backs. But the eastern diamondback has much more to offer than it’s exterior.
What is an Eastern Diamondback Rattlesnake?
The Eastern diamondback rattlesnake (Crotalus adamanteus) is a highly venomous pit viper species found throughout the southeastern United States. It’s the largest of the 32 species of rattlesnakes currently recognized and is the heaviest but not the longest venomous snake found in the Americas.
This snake enjoys quite a bit of fame, as it was featured prominently in the American Revolution, specifically as a symbol in the Gadsden flag, which many consider being the first flag of the United States of America
The Eastern Diamondback Rattlesnake has an Incredible Size
Maximum reported lengths for eastern diamondback rattlesnakes are 8 ft (2.4 m). and 8.25 ft (2.5 m). However, the stated maximum sizes have been called into question due to a lack of voucher specimens. The average length is much smaller.
Average lengths are given as 3.5 to 5.5 ft (1.1 to 1.7 m), and 2.75 to 6 ft (0.8 to 1.8 m). There was one eastern diamondback rattlesnake specimen shot in 1946 that measured 7.8 ft (2.4 m) in length and weighing 15.4 kg (34 lb).
Eastern diamondback rattlesnakes are the largest rattlesnake species and are
the heaviest known type of venomous snake.
However, other venomous snakes may rival this species in weight, the much longer but more slender king cobra is probably greater in average body mass if not maximum weight and the shorter but even bulkier gaboon viper could (but is not verified
One study found an average length of 5.6 ft (1.7 m) based on 31 males and 43 females. The average body mass is roughly 2.3 kg (5.1 lb). The average weight of 9 laboratory-kept specimens was 2.55 kg (5.6 lb), with a range of 0.8 to 4.9 kg (1.8 to 10.8 lb).
Few specimens can exceed 5.12 kg (11.3 lb), although exceptional specimens can weigh 6.7 kg (15 lb) or more. Males are larger than females.
The Eastern Diamondback Rattle Snake has Unique Scalation
The scalation includes 25–31 (usually 29) rows of dorsal scales at midbody, 165–176/170–187 ventral scales in males/females and 27–33/20–26 subcaudal scales in males/females, respectively. On the head, the rostral scale is higher than it is wide and contacts two internasal scales.
There are 10–21 scales in the internasal-prefrontal region and 5–11 (usually 7–8) intersupraocular scales. Usually, there are two loreal scales between preoculars and the postnasal. There are 12–17 (usually 14–15) supralabial scales, the first of which is in broad contact with the prenasal, and 15–21 (usually 17–18) sublabial scales.
Eastern Diamondback Rattlesnakes are known for Their Color Pattern
The color pattern consists of a brownish, brownish-yellow, brownish-gray or olive ground color, overlaid with a series of 24–35 dark brown to black diamonds with slightly lighter centers.
Each of these diamond-shaped blotches is outlined with a row of cream or yellowish scales. Posteriorly, the diamond shapes become more like crossbands and are followed by 5–10 bands around the tail. The belly is a yellowish or cream-colored, with diffused, dark mottling along the sides.
The head has a dark postocular stripe that extends from behind the eye
Eastern Diamondback Rattlesnakes have aliases.
Common names include:
- Eastern diamondback rattlesnake
- Eastern diamond-backed rattlesnake
- Eastern diamondback
- Diamond rattlesnake
- Diamond-back rattlesnake
- Common rattlesnake
- Diamond-back
- Diamond(-patch) rattler
- Eastern diamond-back (rattlesnake)
- Eastern diamond rattlesnake
- Florida diamond-back (rattlesnake)
- Florida rattlesnake
- Lozenge-spotted rattlesnake
- Rattler
- Rattlesnake
- Southeastern diamond-backed rattlesnake
- Southeastern diamond-backed rattler
- Southern woodland rattler
- Water rattle
- Water rattlesnake
- Diamondback rattlesnake
What is the Habitat and Range of the Eastern Diamondback Rattlesnake?
Eastern Diamondback Rattlesnakes are found throughout the
- Upland dry pine forests
- Pine and
Palmetto - Flatwoods
- Sandhills
- Coastal maritime hammocks
- Longleaf pine/turkey oak habitats,
- Grass-sedge marshes
- Swamp forest
- Cypress
swamps - Mesic hammocks
- Sandy mixed woodlands
- Xeric hammocks
- Salt marshes
- Wet prairies during dry periods
In many areas, they seem to use burrows made by gophers and gopher tortoises during the summer and winter.
Although they are very capable swimmers, that can travel through saltwater to and from barrier islands along the Georgia coast and in the Florida Keys, sometimes miles from land. They will usually avoid wet habitats but sometimes can be found along the edges of swampy areas.
Do Eastern Diamondback Rattlesnakes have a Conservation Status?
This species is classified as Least Concern on the IUCN Red List (v3.1, 2001).
Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was down when assessed in 2007.
In North Carolina, the eastern diamondback rattlesnake is protected by state law and considered endangered within the state and is likely extirpated in Louisiana, having last been observed there in 1995. In fact, some scientists and conservationists believe they may even be extirpated in North Carolina.
This species is currently under review for being added to the Endangered Species List by the United States Fish and Wildlife Service due to their recent declines, and their current population represents only 3% of their historical population.
Eastern Diamondback Rattlesnakes have Some Interesting and Commonly Unknown Talents
These snakes frequently shelter by tunneling in gopher and tortoise burrows, emerging in the early morning or afternoon to bask.
Like most rattlesnakes, this species is terrestrial and not adept at climbing. However, they have on occasion been reported in bushes and trees, apparently in search of prey. Even large specimens have been spotted as high as 10 m above the ground.
Eastern Diamondback Rattlesnakes are known to be excellent swimmers.
Specimens have often been spotted crossing stretches of water between barrier islands and the mainland off the Georgia coast, in the Gulf of Mexico and in the Florida Keys, sometimes miles from land.
Individual disposition varies, with some allowing close approach while remaining silent, and others starting to rattle at a distance of 20–30 ft (6–9 m). The rattle is well developed and can be heard from relatively far away.
When threatened, they raise the anterior half of their bodies off the ground in an S-shaped coil and can strike to a distance of at least a third of their body length. Many will stand their ground and may strike repeatedly, but if given the opportunity, they will usually retreat while facing the intruder and moving backward towards shelter, after which they disappear.
One popular myth is these snakes must rattle before striking. To the contrary, these snakes are quite capable of striking while remaining completely silent.
How do Eastern Diamondback Rattlesnakes Find Their Prey?
These snakes forage actively or lie in ambush for small mammals, especially rabbits and rice rats. Their diets also include birds. Prey is struck and released, after which the snake follows the scent trail left by the dying prey.
Because of their large size, adults have no problem eating prey as large as fully grown cottontail rabbits.
As the juveniles are capable of swallowing adult mice, they do not often resort to eating slimmer prey, such as lizards. In fact, eastern cottontails and marsh rabbits form the bulk of their diets in most parts of Florida.
Squirrels, rats, and mice are also eaten, along with birds such as towhees and bobwhite quail. Some other prey that has been reported includes a king rail, a young wild turkey, and a mother woodpecker along with four of her eggs. They also eat large insects.
How do Eastern Diamondback Rattlesnakes Reproduce?
Rattlesnakes, including our friend the eastern diamondback rattlesnake, are ovoviviparous. backward means that the eggs mature and hatch inside of the female, thus allowing her to give birth to already mature snakes.
Gestation lasts six or seven months and broods average about a dozen young. However, the young only stay with the mother for a few hours before they set off on their own to hunt and find cover, thus mortality rate is very high.
Females give birth to between 7 and 21 young at a time, usually between July and early October. Neonates are 12–14 in (30–36 cm) in length and are similar in appearance to the adults, except for having only a small button instead of a rattle on the tip of their tails.
Eastern Diamondback Rattlesnakes are living longer in Captivity
Eastern diamondbacks can live beyond 20 years, but life expectancy in the wild is now typically shorter because of hunting and human expansion.
Adult wild-caught specimens are often difficult to maintain in captivity, but captive-born individuals do quite well and feed readily on killed laboratory rodents. They require a dry and well-ventilated cage with a hide-box, maintained at a temperature of 73–80 °F (23–27 °C) for normal activity.
Eastern Diamondback Rattlesnakes have a unique Venom
This species has the reputation of being the most dangerous venomous snake in North America. While not usually aggressive, they are large and powerful. Wright and Wright mentioned a mortality rate of 30%, but other studies show a mortality rate of 10-20%.
In proportion to its length, it has the longest fangs of any rattlesnake species, with calculations leading one to expect an 8-ft specimen would have fangs with a total length of over 1 in (25 mm). For comparison, a 5-ft specimen had fangs measuring 2⁄3-inch (17 mm) in length. It has a very high venom yield, an average of 400–450 mg, with a maximum of 858-1,000 mg.
Brown gives an average venom yield of 410 mg (dried venom), along with LD50 values of 1.3-2.4 mg/kg IV, 1.7-3.0 mg/kg IP and 14.5–10 mg/kg SC for toxicity. The estimated human lethal dose is 100–150 mg. Baby rattlesnakes are more dangerous than adults because they have less control over their venom.
The venom contains a thrombin-like enzyme, “crotalase”, capable of clotting fibrinogen, leading to the secondary activation of plasminogen from endothelial cells.
Although the venom does not activate platelets, the production of fibrin strands can result in a reduced platelet count, as well as the hemolysis of red blood cells. Even with this defibrination, however, clinically significant bleeding is uncommon. Nevertheless, the venom does exhibit high hemorrhagic activity.
It also contains a low-molecular-weight basic peptide that impedes neuromuscular transmission and can, in theory, lead to cardiac failure. This peptide is similar to crotamine from the South American Rattlesnake and makes up 2-8% of the protein found in the venom.
In general, the venom can be described as highly necrotizing, mildly proteolytic and containing a large phosphodiesterase fraction.
It stimulates the release of bradykinin that can result in severe pain, as well as profound, transient hypotension.
Klauber described one case in which the symptoms included instant pain “like two hot hypodermic needles”, spontaneous bleeding from the bite site, intense internal pain, bleeding from the mouth, hypotension, a weak pulse, swelling and discoloration of the affected limb, and associated severe pain. The symptoms were further described as strongly hemolytic and hemorrhagic.
CroFab and Wyeth’s ACP are effective antivenoms against bites from this species, although massive doses may be needed to manage severe cases of envenomation. Generally, ACP is very effective at countering the defibrination syndrome that is often seen but may do little for low platelet counts. Wyeth’s ACP is no longer being manufactured.
Venom Variations – Location
Researcher Darin Rokyta and colleagues with Florida State University collected and analyzed venom from the eastern coral snake and found that wherever the coral snake was captured, the protein makeup of the venom collected from one part of the state of Florida was the same as the venom collected from the same species in another part of the state.
With the eastern diamondback rattlesnake, however, the genetic makeup of the venom of one snake collected in the Everglades was distinctly different from the venom collected from the same species of snake in the Florida panhandle, which is about 500 miles from the Everglades.
The researchers found that two venom components, one which causes paralysis, was found in high levels in the northernmost populations of the snake but were nonexistent in the venom of the snakes on Caladesi Island along Florida’s Gulf Coast.
“We were shocked,”
Rokyta said in a statement released by the university, “This is the first time anyone has looked at venom variation at this scale, and everybody has assumed that the co-evolutionary arms race would cause local populations to diverge quickly.”
Part of the abstract of that study reads,
“We sequenced adult/juvenile pairs of venom-gland transcriptomes from five populations previously shown to have different adult venom compositions. We identified a total of 59 putative toxin transcripts.”
Rokyta explains the lack of change in variation of the eastern coral snake venom could be caused by a small population of the reptile had expanded and dominated the entire range and reducing genetic diversity, or it is a difference in the co-evolutionary dynamics between the snake and its reptilian prey.
The implications could potentially have a huge impact on researchers who develop antivenom as well as the conservation efforts of the eastern diamondback rattlesnake, which is under consideration for Endangered Species Act protections. The data collected by Rokyta could also be used for conservation management to ensure that populations of the snake with different venom subtypes are preserved to keep the species viable.
Why Do Rattlesnakes have Rattles?
When cornered, rattlers feverishly shake their iconic tails as a last warning to back off. Rattles are made of loosely attached, hard, hollow segments. Snakes add a new rattle segment each time they shed. However, rattles break off frequently, and snakes may shed their skin several times a year, so it is not possible to determine a snake’s age by its rattle size.
Related Questions
How many types of pit viper are there? There are quite a few types of pit viper, found all around the world. Currently, there are about 190 different species.
Are all pit vipers rattlesnakes? Not all pit vipers have rattles. However, all pit vipers share the ability to use heat-sensing pits to hunt their prey.
Why can’t the size of a snake’s rattle tell how old it is? It’s true that when baby rattlers are born, they have a little button where their rattle will be. As they shed, the rattle grows. However, oftentimes the rattle will be hit with something or get caught somewhere as the snake moves, thus breaking it. So the length of the rattle is unreliable as a sign of age.
