The eastern diamondback rattlesnake (''Crotalus adamanteus'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of pit viper in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Viperidae The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs th ...

. The species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the

Southeastern United States The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern por ...

. It is one of the heaviest

venomous snake Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow or g ...

s in the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

and the largest rattlesnake. No subspecies are recognized.

Description

The eastern diamondback rattlesnake is the largest rattlesnake species and is one of the heaviest known species of venomous snake, with one specimen shot in 1946 measuring in length and weighing . However, other venomous snakes may rival this species in weight such as the much longer but more slender king cobra and the shorter but even bulkier

Gaboon viper The Gaboon viper (''Bitis gabonica''), also called the Gaboon adder, is a viper species found in the rainforests and savannas of sub-Saharan Africa.McDiarmid RW, Campbell JA, Touré T. 1999. ''Snake Species of the World: A Taxonomic and Geog ...

. Maximum reported lengths for the eastern diamondback rattlesnake are and . However, the stated maximum sizes have been called into question due to a lack of voucher specimens. Males are typically larger than females, which is rare among snakes (females are usually larger than males). Specimens over are rare, but well documented. Klauber (1998) included a letter he received from E. Ross Allen in 1953, in which Allen explains how for years he offered a reward of $100, and later $200, for an specimen, dead or alive. The reward was never claimed. He did receive a number of range specimens and some skins, but said such skins can be taken from specimens as short as . A specimen was caught and killed outside a neighborhood in St. Augustine, Florida in September 2009. The average size is much less. Specimens are rarely found over 6 feet in length. Lengths of ,United States Navy (1991). ''Poisonous Snakes of the World''. New York: US Government / Dover Publications Inc. 204 pp. . and are given.Conant R (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition''. First published in 1958. Boston: Houghton Mifflin Company. xviii + 429 pp. + 48 plates. (hc), (pb). One study found an average length of based on 31 males and 43 females. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. (7th printing, 1985). 1,105 pp. . The average body mass is roughly . The average weight of 9 laboratory-kept specimens was , with a range of . Few specimens can exceed , although exceptional specimens can weigh or more. The scalation includes 25–31 (usually 29) rows of

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down t ...

at midbody, 165–176/170–187

ventral scales In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

in males/females and 27–33/20–26 subcaudal scales in males/females, respectively. On the head, the

rostral scale The rostral scale, or rostral, in snakes and other scaled reptiles is the median plate on the tip of the snout that borders the mouth opening. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: ...

is higher than it is wide and contacts two

internasal scales In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates. (7t ...

. There are 10–21 scales in the internasal- prefrontal region and 5–11 (usually 7–8)

intersupraocular scales In snakes, the interorbital scales, or intersupraoculars, are the scales on the top of the head between the plates surmounting the eyesWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . ( ...

. Usually, there are two

loreal scales The lore (adj. loreal) is the region between the eyes and nostrils of birds, reptiles, and amphibians. Ornithology In ornithology, the lore is the region between the eye and bill on the side of a bird's head. This region is sometimes featherles ...

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 In reptiles, the nasal scale refers to the scale that encloses the nostril.Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. . Sometimes this ...

, and 15–21 (usually 17–18) sublabial scales. 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 backwards and downwards to the lip; the back of the stripe touches the angle of the mouth. Anteriorly and posteriorly, the postocular stripe is bordered by distinct white or yellow stripes. The rattle at the end of their tail is made of hard, loosely attached, hollow segments which break off frequently and are completely replaced when the snake sheds.

Common names

Other common names for this snake species include 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, timber rattler, water rattle, water rattlesnake, and diamondback rattlesnake.

Geographic range

The eastern diamondback rattlesnake is found in the

from southeastern

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and ...

, south along the coastal plain through peninsular

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

to the Florida Keys, and west along the Gulf Coast through southern

Alabama (We dare defend our rights) , anthem = "Alabama" , image_map = Alabama in United States.svg , seat = Montgomery , LargestCity = Huntsville , LargestCounty = Baldwin County , LargestMetro = Greater Birmingham , area_total_km2 = 135,765 ...

and

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

to southeastern

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

. The original description for the species does not include a type locality, although Schmidt (1953) proposed it be restricted to " Charleston, South Carolina" (USA). McDiarmid RW, Campbell JA, Touré T (1999). ''Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1''. Washington, District of Columbia. Herpetologists' League. 511 pp. (series). (volume).

Conservation status

This snake species is classified as Least Concern on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

(v3.1, 2001). Species are listed as such owing to their wide distribution or 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. It is likely extirpated in

, having last been observed there in 1995. In fact some scientists and conservationists believe it may even be extirpated in North Carolina, having last been observed there in the early 1990s. This species is currently under review for being added to the Endangered Species List by the

United States Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with othe ...

owing to its recent decline, and the current population represents only 3% of the historical population.

Habitat

The eastern diamondback rattlesnake inhabits upland dry pine forest, pine and palmetto

flatwoods Flatwoods, pineywoods, pine savannas and longleaf pine-wiregrass ecosystem are terms that refer to an ecological community in the southeastern coastal plain of North America. Flatwoods are an ecosystem maintained by wildfire or prescribed fire and ...

sandhill A sandhill is a type of ecological community or xeric wildfire-maintained ecosystem. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and bec ...

s and coastal maritime hammocks,

longleaf pine The longleaf pine (''Pinus palustris'') is a pine species native to the Southeastern United States, found along the coastal plain from East Texas to southern Virginia, extending into northern and central Florida. In this area it is also known as ...

turkey oak Turkey oak is a common name for several species of oaks and may refer to: *''Quercus cerris'', native to southeastern Europe and Asia Minor *''Quercus laevis ''Quercus laevis'', the turkey oak, is a member of the red oak group of oaks. It is n ...

habitats, grass-sedge marshes and swamp forest, cypress swamps, mesic hammocks, sandy mixed woodlands, xeric hammocks, and

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...

es, as well as wet prairies during dry periods. In many areas, it seems to use burrows made by

gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...

s and gopher tortoises during the summer and winter.

Behavior

The eastern diamondback rattlesnake frequently shelters by tunneling in gopher and tortoise burrows, emerging in the early morning or afternoon to bask.Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . Like most rattlesnakes, this species is terrestrial and not adept at climbing. However, it has on occasion been reported in bushes and trees, apparently in search of prey. Even large specimens have been spotted as high as above the ground. It is also known to be an excellent swimmer. Specimens have often been spotted crossing stretches of water between

barrier island Barrier islands are coastal landforms and a type of dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything from ...

s and the mainland off the

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

coast, in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

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 . The rattle is well developed and can be heard from relatively far away. When threatened, it raises the anterior half of the body off the ground in an S-shaped coil, and can strike to a distance of at least a third of its body length.Ashton RE Jr, Sawyer-Ashton P (1981). ''Handbooks of Reptiles and Amphibians of Florida, Part 1, The Snakes''. Miami, Florida: Windward Publishing Inc. 176 pp. LCCCN 81-51066. . Many will stand their ground and may strike repeatedly, but if given the opportunity, they will usually retreat while facing the intruder and moving backwards towards shelter, after which they disappear. One popular myth is that the eastern diamondback rattlesnake must rattle before striking. To the contrary, it is quite capable of striking while remaining completely silent.Eastern Diamondback Rattlesnake
a
Florida Museum of Natural History
Accessed 2 July 2008. Hawks, eagles, and other snakes have been known to prey upon young and adolescent specimens of the eastern diamondback rattlesnake.

Feeding

The eastern diamondback rattlesnake forages actively or lies in ambush for small mammals, especially rabbits and rice rats (''

Oryzomys ''Oryzomys'' is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (''O. palustris'') of the United States and ...

''). The diet also includes 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 (''

Sylvilagus Cottontail rabbits are the leporid species in the genus ''Sylvilagus'', found in the Americas. Most ''Sylvilagus'' species have stub tails with white undersides that show when they retreat, giving them their characteristic name. However, this ...

'') form the bulk of the diet in most parts of Florida. Squirrels, rats, and mice are also eaten, along with birds such as

towhee A towhee is any one of a number of species of birds in the genus ''Pipilo'' or ''Melozone'' within the family Passerellidae (which also includes American sparrows, and juncos). Towhees typically have longer tails than other Passerellidae. Most ...

s and

bobwhite quail The northern bobwhite (''Colinus virginianus''), also known as the Virginia quail or (in its home range) bobwhite quail, is a ground-dwelling bird native to Canada, the United States, Mexico, and Cuba, with introduced populations elsewhere in t ...

. Other prey that have been reported include a king rail, a young

wild turkey The wild turkey (''Meleagris gallopavo'') is an upland ground bird native to North America, one of two extant species of turkey and the heaviest member of the order Galliformes. It is the ancestor to the domestic turkey, which was originally d ...

, and a mother woodpecker along with four of her eggs. It also eats large insects.

Reproduction

Rattlesnakes, including the eastern diamondback, are

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

. Gestation lasts six or seven months and

brood Brood may refer to: Nature * Brood, a collective term for offspring * Brooding, the incubation of bird eggs by their parents * Bee brood, the young of a beehive * Individual broods of North American Periodical Cicadas: ** Brood X, the largest b ...

s average about a dozen young. However, the young only stay with the mother 10–20 days before they set off on their own to hunt and find cover. Females give birth to between 7 and 21 young at a time, usually between July and early October. Neonates are in length Behler JL, King FW (1979). ''The Audubon Society Field Guide to North American Reptiles and Amphibians''. New York: Alfred A. Knopf. 743 pp. LCCCN 79-2217. . 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.

Captivity

The eastern diamondback can live beyond 20 years, but life expectancy in the wild is now typically shorter because of hunting and human expansion. Crotalus adamanteus IMG 5058

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. The eastern diamondback requires a dry and well-ventilated cage with a hide-box, maintained at a temperature of for normal activity.

Venom

The eastern diamondback rattlesnake has the reputation of being the most dangerous

in North America. While not usually aggressive, it is large and powerful.

Wright Wright is an occupational surname originating in England. The term 'Wright' comes from the circa 700 AD Old English word 'wryhta' or 'wyrhta', meaning worker or shaper of wood. Later it became any occupational worker (for example, a shipwright i ...

and

mentioned a mortality rate of 30%, but other studies show a mortality rate of 10–20% (untreated). In proportion to its length, it has the longest fangs of any rattlesnake species, with calculations leading one to expect an specimen would have fangs with a total length of over . For comparison, a specimen had fangs measuring in length. It has a very high venom yield, an average of 400–450 mg, with a maximum of 858–1,000 mg.Norris R (2004). "Venom Poisoning in North American Reptiles". ''In'': Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publishing Associates. 870 pp. 1,500 plates. . Brown gives an average venom yield of 410 mg (dried venom), along with 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.Brown JH (1973). ''Toxicology and Pharmacology of Venoms from Poisonous Snakes''. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. . The estimated human lethal dose is 100–150 mg. The venom contains a

thrombin Thrombin (, ''fibrinogenase'', ''thrombase'', ''thrombofort'', ''topical'', ''thrombin-C'', ''tropostasin'', ''activated blood-coagulation factor II'', ''blood-coagulation factor IIa'', ''factor IIa'', ''E thrombin'', ''beta-thrombin'', ''gamma- ...

-like

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

, "crotalase", capable of clotting

fibrinogen Fibrinogen (factor I) is a glycoprotein complex, produced in the liver, that circulates in the blood of all vertebrates. During tissue and vascular injury, it is converted enzymatically by thrombin to fibrin and then to a fibrin-based blood cl ...

, leading to the secondary activation of

plasminogen Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is encode ...

from

endothelial The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...

cells. Although the venom does not activate

platelet Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby i ...

s, the production of fibrin strands can result in a reduced platelet count, as well as the

hemolysis Hemolysis or haemolysis (), also known by several other names, is the rupturing ( lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

s (see article on

MAHA Maha and MAHA may refer to: * Maha (name), an Arabic feminine given name * ''Maha'' (film), a Tamil thriller film * MaHa, Nepali comedy duo, Madan Krishna Shrestha and Hari Bansha Acharya * Maha Music Festival, an annual music festival held on ...

). Even with this defibrination, however, clinically significant bleeding is uncommon. Nevertheless, the venom does exhibit high

hemorrhagic Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

activity. It also contains a low-molecular-weight basic

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. ...

that impedes neuromuscular transmissionLee, 1972. and can in theory lead to

cardiac failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...

. This peptide is similar to crotamine from '' C. durrisus terrificus'', and makes up 2–8% of the protein found in the venom. In general, the venom can be described as highly

necrotizing Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

, mildly

proteolytic Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called protease ...

and containing a large

phosphodiesterase A phosphodiesterase (PDE) is an enzyme that breaks a phosphodiester bond. Usually, ''phosphodiesterase'' refers to cyclic nucleotide phosphodiesterases, which have great clinical significance and are described below. However, there are many ot ...

fraction. It stimulates the release of

bradykinin Bradykinin (BK) (Greek brady-, slow; -kinin, kīn(eîn) to move) is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor and ...

that can result in severe pain, as well as profound, transient

hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...

. 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, ANAVIP, and

Wyeth Wyeth, LLC was an American pharmaceutical company. The company was founded in Philadelphia, Pennsylvania, in 1860 as ''John Wyeth and Brother''. It was later known, in the early 1930s, as American Home Products, before being renamed to Wyeth in ...

's ACP are effective antivenins 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.