Common names: eastern diamondback rattlesnake, eastern diamondback, more.

Crotalus adamanteus is a venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pit viper

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 found in the southeastern United States

Southeastern United States

The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....

. It is the heaviest (though not longest) venomous snake in the Americas

Americas

The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

 and the largest rattlesnake

Rattlesnake

Rattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae . There are 32 known species of rattlesnake, with between 65-70 subspecies, all native to the Americas, ranging from southern Alberta and southern British Columbia in Canada to Central...

. It featured prominently in the American Revolution, specifically as the symbol of what many consider to be the first flag of the United States of America, the Gadsden flag

Gadsden flag

The Gadsden flag is a historical American flag with a yellow field depicting a rattlesnake coiled and ready to strike. Positioned below the snake is the legend "DONT TREAD ON ME." The flag was designed by and is named after American general and statesman Christopher Gadsden. It was also used by the...

. No subspecies are currently recognized.

Description

This is the largest rattlesnake species and, according to the Guinness Book of World Records, is the heaviest venomous snake. The heaviest known specimen, measuring 7.8 feet (2.4 m) in length, was shot in 1946 and weighed 15.4 kilograms (34 lb). Maximum reported lengths are 8 feet (2.4 m) and 8.25 feet (2.5 m). However, the stated maximum sizes have been called into question due to a lack of voucher specimens.

Specimens over 7 feet (2.1 m) are rare, but well documented. Klauber (1998) includes a letter he received from E. Ross Allen

Ross Allen (herpetologist)

Ensil Ross Allen was an American herpetologist and writer. Born in Pennsylvania, Ross relocated to Florida with his family when he was a teenager. As a young man, Allen made a hobby of capturing turtles, snakes and other reptiles near his home in central Florida.Allen began the Reptile Institute...

 in 1953, in which Allen explains how for years he offered a reward of $100, and later $200, for an 8 feet (2.4 m) specimen, dead or alive. The reward was never claimed. He did receive a number of 7-foot specimens and some 8-foot skins, but said that such skins can be taken from a 6-foot snake. A 7.3 feet (2.2 m) specimen was caught and killed outside a neighborhood in St. Augustine, Florida

St. Augustine, Florida

St. Augustine is a city in the northeast section of Florida and the county seat of St. Johns County, Florida, United States. Founded in 1565 by Spanish explorer and admiral Pedro Menéndez de Avilés, it is the oldest continuously occupied European-established city and port in the continental United...

 in September 2009.

The average size is much less: lengths of 3.5 to 5.5 ft (1.1 to 1.7 m), and 2.75 to 6 ft (0.8382 to 1.8 m) are given. One study found an average length of 5.6 feet (1.7 m) based on 31 males and 43 females.

The scalation includes 25-31 (usually 29) rows of dorsal scales

Dorsal scales

In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales.When counting dorsal scales, numbers are often given for three points along the body, for example 19:21:17...

 at midbody, 165-176/170-187 ventral scales

Ventral scales

In snakes, the ventral scales 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 contacts the paraventral row of dorsal scales on either side...

 in males/females and 27-33/20-26 subcaudal scales

Subcaudal scales

In snakes, the subcaudal scales are the enlarged plates on the underside of the tail. These scales may be either single or divided and are preceded by the anal scale....

 in males/females. On the head, the rostral scale is higher than it is wide and contacts two internasal scales

Internasal scales

In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. They are usually paired and situated just behind the rostral....

. There are 10-21 scales in the internasal

Internasal scales

In snakes, the internasal scales are those on top of the head between the scales that surround the nostrils. They are usually paired and situated just behind the rostral....

-prefrontal

Prefrontal scales

The prefrontal scales on snakes and other reptiles are the scales connected to the frontals towards the tip of the snout which are in contact with the internasals....

 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

Supralabial scales

In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scale . The term labial originates from Labium , which refers to any lip-like structure...

, the first of which is in broad contact with the prenasal, and 15-21 (usually 17-18) sublabial scales

Sublabial scales

In reptiles, the sublabial scales, also called lower-labials or infralabials, are those scales that border the mouth opening along the lower jaw. They do not include the median scale . The term labial originates from Labium , which refers to any lip-like structure...

.

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 cross-bands 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.

Common names

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, and diamondback rattlesnake.

Geographic range

C. adamanteus is found in the southeastern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 from southeastern North Carolina

North Carolina

North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

, south along the coastal plain through peninsular Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

 to the Florida Keys

Florida Keys

The Florida Keys are a coral archipelago in southeast United States. They begin at the southeastern tip of the Florida peninsula, about south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry...

, and west along the Gulf Coast through southern Mississippi

Mississippi

Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...

 to southeastern Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

. The original description for the species does not include a type locality, although Schmidt (1953) proposed it be restricted to "Charleston, South Carolina

Charleston, South Carolina

Charleston is the second largest city in the U.S. state of South Carolina. It was made the county seat of Charleston County in 1901 when Charleston County was founded. The city's original name was Charles Towne in 1670, and it moved to its present location from a location on the west bank of the...

" (USA).

Conservation status

This species is classified as Least Concern (LC) on the IUCN

World Conservation Union

The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

 Red List of Threatened Species

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was down when assessed in 2007.

This species has been declining for years due to habitat destruction, hunting and persecution. The decline of these snakes has been suggested as the cause for the rabbit population in Florida rising.

Habitat

This rattlesnake inhabits upland dry pine forest, pine and palmetto flatwoods

Flatwoods

Flatwoods, Pineywoods, Longleaf Pine-Wiregrass Ecosystem refers to an ecological community in the Southeastern coastal plain of North America...

, sandhill

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 become more oak dominated.Entisols are the typical...

s and coastal maritime hammocks, longleaf pine

Longleaf Pine

Pinus palustris, commonly known as the Longleaf Pine, is a pine native to the southeastern United States, found along the coastal plain from eastern Texas to southeast Virginia extending into northern and central Florida....

/turkey oak habitats, grass-sedge marshes and swamp forest, cypress swamps, mesic hammocks, sandy mixed woodlands, xeric hammocks, and salt marsh

Salt marsh

A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...

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

Gopher (animal)

The term gopher as it is commonly used does not relate to any one species, but is a generic term used to describe any of several small burrowing rodents endemic to North America, including the pocket gopher , also called true gophers, and the ground squirrel , including Richardson's ground squirrel...

s and gopher tortoises

Gopherus polyphemus

The gopher tortoise is a species of the Gopherus genus native to the southeastern United States. The gopher tortoise is seen as a keystone species because it digs burrows that provide shelter for 360 other animal species...

 during the summer and winter.

Behavior

These snakes frequently shelter in mammal and gopher tortoise

Gopherus polyphemus

The gopher tortoise is a species of the Gopherus genus native to the southeastern United States. The gopher tortoise is seen as a keystone species because it digs burrows that provide shelter for 360 other animal species...

 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 much as 10 m above the ground.

In contrast, they are well known to be excellent swimmers. Specimens have often been spotted crossing stretches of water between barrier island

Barrier island

Barrier islands, a coastal landform and a type of barrier system, are relatively narrow strips of sand that parallel the mainland coast. They usually occur in chains, consisting of anything from a few islands to more than a dozen...

s and the mainland off the Georgia

Georgia (U.S. state)

Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

 coast, in the Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

 and in the Florida Keys

Florida Keys

The Florida Keys are a coral archipelago in southeast United States. They begin at the southeastern tip of the Florida peninsula, about south of Miami, and extend in a gentle arc south-southwest and then westward to Key West, the westernmost of the inhabited islands, and on to the uninhabited Dry...

, 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 (6.1–9.1 m). The rattle is well developed and can be heard from relatively far away. When threatened, they raise 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 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 backwards towards shelter, after which they disappear.

One popular myth is that these snakes must rattle before striking. They are, of course quite capable of striking while remaining completely silent. In fact, according to one hypothesis, individuals that remain silent are less likely to be heard, seen and killed, and therefore more likely to pass on their genes to the next generation, leading to the idea that we are selecting

Natural selection

Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

 for rattlesnakes that do not rattle.

Hawks, eagles, and other snakes have been known to prey upon young and adolescent specimens.

Feeding

These snakes forage actively or lie in ambush for small mammals, especially rabbits and rice rats (Oryzomys

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 of the United States and O. couesi of Mexico and Central America—are widespread; the six others have...

). Their diet also includes birds. Prey is struck and released, after which they follow the scent trail left by the dying prey.

Because of their large size, the adults have no problem eating prey as large as fully-grown cottontail rabbits. As the juveniles are capable of swallowing adult mice, even they do not often resort to eating slimmer prey, such as lizards. In fact, eastern cottontails and marsh rabbits (Sylvilagus) form the bulk of their diets in most parts of Florida. Squirrels, rats, and mice are also on the menu, along with birds such as towhee

Towhee

A towhee is any one of a number of species of birds in the genus Pipilo or Melozone within the family Emberizidae ....

s and bobwhite quail

Bobwhite Quail

The Northern Bobwhite, Virginia Quail or Bobwhite Quail is a ground-dwelling bird native to the United States, Mexico, and the Caribbean...

. Other prey that have been reported include a king rail

King Rail

The King Rail, Rallus elegans, is a waterbird, the largest North American rail.Distinct features are a long bill with a slight downward curve, with adults being brown on the back and rusty-brown on the face and breast with a dark brown cap. They also have a white throat and a light belly with...

, a young wild turkey

Wild Turkey

The Wild Turkey is native to North America and is the heaviest member of the Galliformes. It is the same species as the domestic turkey, which derives from the South Mexican subspecies of wild turkey .Adult wild turkeys have long reddish-yellow to grayish-green...

, and a mother woodpecker along with four of her eggs.
They also eat large insects.

Reproduction

Rattlesnakes, including C. adamanteus, are ovoviviparous. Gestation periods last six or seven months and brood

Offspring

In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

s average about a dozen young. However, the young only stay with the mother for a few hours (even days) before they set off on their own to hunt and find recluse, thus mortality rate is very high.

Females give birth to between seven and 21 young at a time, usually doing so between July to early October. Neonates are 12–14 in (30.5–35.6 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 the tail.

Captivity

Eastern diamondbacks can live beyond twenty 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 (22.8–26.7 C) for normal activity.

Venom

This species has the reputation of being the most dangerous venomous snake

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. While not usually aggressive, they are large and powerful. Wright and Wright mention 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 feet (2.4 m) specimen would have fangs with a total length of over 1 inches (25 mm). For comparison, a 5 in 3 in (1.6 m) specimen had fangs measuring 2/3 in 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 values of 1.3-2.4 mg/kg IV

Intravenous therapy

Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...

, 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.

The venom contains a thrombin

Thrombin

Thrombin is a "trypsin-like" serine protease protein that in humans is encoded by the F2 gene. Prothrombin is proteolytically cleaved to form thrombin in the first step of the coagulation cascade, which ultimately results in the stemming of blood loss...

-like enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 (TLE), called "crotalase", that is capable of clotting fibrinogen

Fibrinogen

Fibrinogen is a soluble plasma glycoprotein, synthesised by the liver, that is converted by thrombin into fibrin during blood coagulation. This is achieved through processes in the coagulation cascade that activate the zymogen prothrombin to the serine protease thrombin, which is responsible for...

, leading to the secondary activation of plasminogen from endothelial cells. Although the venom does not activate platelet

Platelet

Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days...

s, the production of fibrin

Fibrin

Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....

 strands can result in a reduced platelet count, as well as the hemolysis

Hemolysis

Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...

 of red blood cell

Red blood cell

Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s. Even with this defibrination, however, clinically significant bleeding is uncommon (Hasiba et al., 1975). Nevertheless, the venom does exhibit high hemorrhagic activity (Minton, 1974). It also contains a low-molecular-weight basic peptide

Peptide

Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

 that impedes neuromuscular transmission (Lee, 1972) and can in theory lead to cardiac failure. This peptide is similar to crotamine from C. durrisus terrificus

Crotalus durissus

Crotalus durissus is a venomous pitviper species found in South America. The most widely distributed member of its genus, this species poses a serious medical problem in many parts of its range...

, and makes up 2-8% of the protein found in the venom. In general, the venom can be described as highly necrotizing

Necrosis

Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

, mildly proteolytic

Proteolysis

Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...

 and containing a large phosphodiesterase

Phosphodiesterase

A phosphodiesterase is any enzyme that breaks a phosphodiester bond. Usually, people speaking of phosphodiesterase are referring to cyclic nucleotide phosphodiesterases, which have great clinical significance and are described below...

 fraction. It stimulates the release of bradykinin

Bradykinin

Bradykinin is a peptide that causes blood vessels to dilate , and therefore causes blood pressure to lower. A class of drugs called ACE inhibitors, which are used to lower blood pressure, increase bradykinin further lowering blood pressure...

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

Hypotension

In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...

.

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 and 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

CroFab

CroFab is the commercial name for a Crotalidae Polyvalent Immune Fab snake antivenom, indicated for minimal or moderate North American Crotalid snake envenomation. It is developed and manufactured by BTG plc , and distributed in the US by Nycomed Inc...

 and Wyeth

Wyeth

Wyeth, formerly one of the companies owned by American Home Products Corporation , was a pharmaceutical company. The company was based in Madison, New Jersey, USA...

'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.

External links

• Eastern Diamondback Rattlesnake at Yale Herpetology Page. Accessed 2 March 2007.
• Eastern Diamondback Rattlesnake at Biology Dept., Davidson College. Accessed 2 March 2007.
• Images of Crotalus adamanteus at SREL Herpetology. Accessed 2 March 2007.
• Crotalus adamanteus at Munich AntiVenom INdex. Accessed 2 March 2007.