- Common names: eastern diamondback rattlesnake, eastern diamondback, more.
Crotalus adamanteus is a
venomousA venomous snake is a snake that uses modified saliva, snake venom, usually delivered through highly specialized teeth such as hollow fangs, for the purpose of prey immobilization and self-defense...
pitviperThe Crotalinae, or crotalines, 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...
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
found in the
southeastern United StatesThe US Southeast is the eastern portion of the Southern United States, but the Census Bureau does not provide a standard definition of a "Southeast" region of the United States, and organizations that need to subdivide the US are free to define a "Southeast" region to fit their needs...
. It is the heaviest (though not longest) venomous snake in the
AmericasThe Americas, or America, are lands in the Western hemisphere or New World, comprising the continents of North America and South America with their associated islands and regions. America may be ambiguous in English, as it is more commonly used to refer to the United States of America...
and the largest
rattlesnakeRattlesnakes are a group of venomous snakes, genera Crotalus and Sistrurus. They belong to the subfamily of venomous snakes known commonly as pit vipers.-Overview:...
. No subspecies are currently recognized.
Description
The largest rattlesnake species, the maximum sizes reported are (Klauber, 1972) and (Ditmars, 1936). One captive specimen weighed over . However, the stated maximum size has been called into question due to a lack of voucher specimens (Jones, 1997).
Specimens over are rare, but well documented. Klauber (1997) includes 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 specimens and some skins, but said that such skins can be taken from a snake. A 7 ft., 3 in. specimen was caught and killed outside a neighborhood in St. Augustine, FL in Sep. 2009.
The average size is much less: lengths of , are given. One study found an average length of based on 31 males and 43 females.
The scalation includes 25-31 (usually 29) rows of
dorsal scalesIn 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 scalesIn 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 scalesIn 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 2
internasal scalesIn 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
internasalIn 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....
-
prefrontalThe prefrontal scale on a snake 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 2 loreal scales between preoculars and the postnasal. There are 12-17 (usually 14-15)
supralabial scalesIn 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 scalesIn 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 centres. 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 color 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
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, timber rattlesnake, water rattle, water rattlesnake, diamondback rattlesnake.
Geographic range
Found in the southeastern
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
from southeastern
North CarolinaNorth Carolina is a state located on the Atlantic Seaboard 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...
, south along the coastal plain through peninsular
FloridaFlorida is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the north. It was the 27th state admitted to the United States...
to the
Florida KeysThe Florida Keys are a cluster of about 1700 islands in the 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...
, and west along the Gulf Coast though southern
MississippiMississippi is a state located in the Southern United States. Jackson is the state capital and largest city. The state's name comes from the Mississippi River, which flows along its western boundary, and takes its name from the Ojibwe word misi-ziibi . The state is heavily forested outside of the...
to southeastern
LouisianaThe State of 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 divided into parishes, which are local governments equivalent to counties...
. The original description for the species does not include a type locality, although Schmidt (1953) proposed that it be restricted to "
Charleston, South CarolinaCharleston is a city in Charleston County, South Carolina in the U.S. state of South Carolina. It is the largest city and county seat of Charleston County. The city was founded as Charlestown or Charles Towne, Carolina in 1670, and moved to its present location from a location on the west bank of...
" (USA).
Conservation status
This species is not classified as an endangered species as its numbers are considered healthy throughout its range.
Habitat
Inhabits upland dry pine forest, pine and palmetto
flatwoodsFlatwoods, Pineywoods, Longleaf Pine-Wiregrass Ecosystem refers to an ecological community in the Southeastern coastal plain of North America...
,
sandhillA sandhill is a type of ecological community or xeric wildfire-maintained ecosystem in the coastal plain of North America. 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...
s and coastal maritime hammocks,
Longleaf PineThe Longleaf Pine is a pine native to the southeast 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, mesic hammocks, sandy mixed woodlands, xeric hammocks, salt marshes, as well as wet prairies during dry periods. In many areas it seems to use burrows made by
gopherGopher may refer to:* Gopher , including:** True gopher, i.e. pocket gopher or member of Geomyidae, native to North America** Richardson's Ground Squirrel, a species of Spermophilus...
s and
gopher tortoisesThe Gopher Tortoise is a tortoise species native to the southeast United States. The gopher tortoise is seen as a keystone species because it digs burrows which provide shelter for hundreds of other species. They are threatened by predation and habitat destruction...
during the summer and winter.
Behavior
These snakes frequently shelter in mammal and gopher 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 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 islands and the mainland off the
GeorgiaGeorgia is a state in the United States. One of the original Thirteen Colonies that revolted against British rule in the American Revolution, it had been the last of the Thirteen Colonies to be established, in 1733. Georgia was the fourth state to ratify the United States Constitution, on January...
coast, in the
Gulf of MexicoThe Gulf of Mexico is the ninth largest body of water in the world. Considered a smaller part of the Atlantic Ocean, it is an 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...
and in the
Florida KeysThe Florida Keys are a cluster of about 1700 islands in the 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...
, sometimes miles from land.
Individual disposition varies, with some allowing close approach while remaining silent, and others starting to rattle at a distance of 6-9 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 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
selectingNatural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations...
for rattlesnakes that do not rattle.
Hawks, eagles, and other snakes have been known to prey upon young and adolescent specimens.
The Eastern Diamondback rattlesnake is known to be particularly dangerous and can attack without warning.
Feeding
These snakes forage actively or lie in ambush for small mammals, especially rabbits and rice rats (
OryzomysOryzomys is a genus of rodent distributed in North, Central and northern South America. They are part of a diverse tribe of cricetid rodents known as rice rats ....
). 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 diet in most parts of Florida. Squirrels, rats, and mice are also on the menu, along with birds such as towheeA Towhee is any one of a number of species of birds in the genus Pipilo within the family Emberizidae ....
s and Bobwhite QuailThe Northern Bobwhite, Virginia Quail or Bobwhite Quail is a ground-dwelling bird native to the United States, Mexico, and the Caribbean. It is a member of the group of species known as New World quails...
. Other prey that have been reported include a king railThe 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 turkeyThe Wild Turkey is native to North America and is the heaviest member of the Galliformes. It is one of two species of turkey, the other being the Ocellated Turkey, found in Central America....
, and a mother woodpecker along with four of her eggs.
They also eat large insects.
Reproduction
Rattlesnakes, including C. adamanteus, are ovoviviparous. Gestation period lasts six or seven months and
broodBrood may refer to:* Brood, a collective term for offspring* Brooding, the incubation of bird eggs by their parents* Brood , the young of a beehive*Brood: to think deeply about something, often in a dark or melancholy manner....
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 7 and 21 young at a time, usually doing so between July to early October. Neonates are 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 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 pre-killed laboratory rodents. They require a dry and well-ventilated cage with a hide-box, maintained a temperature of 23-27°C for normal activity.
Venom
This species has the reputation of being the most dangerous
venomous snakeA venomous snake is a snake that uses modified saliva, snake venom, usually delivered through highly specialized teeth such as hollow fangs, for the purpose of prey immobilization and self-defense...
in
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
. While not usually aggressive, they are large and powerful. Wright and Wright (1957) mention a mortality rate of 30% and that some victims have died within a matter of hours.
In proportion to its length, it has the longest fangs of any rattlesnake species, with calculations leading us to expect that an 8-foot (240 cm) specimen would have fangs with a total length of 27 mm (over one inch). For comparison, a 160 cm (5 ft. 3 in.) specimen had fangs with a length of 17 mm. It has a very high venom yield: an average of 400-450 mg, with a maximum of 858-1,000 mg. Brown (1973) gives an average venom yield of 410 mg (dried venom), along with
LD50In toxicology, the median lethal dose, LD50 , LC50 or LCt50 of a toxic substance or radiation is the dose required to kill half the members of a tested population...
values of 1.3-2.4 mg/kg
IVIntravenous therapy or IV therapy is the giving of liquid substances directly into a vein. It can be intermittent or continuous; continuous administration is called an intravenous drip. The word intravenous simply means "within a vein", but is most commonly used to refer to IV therapy...
, 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
thrombinThrombin also commonly called pro-thrombin is a coagulation protein in the blood stream that has many effects in the coagulation cascade...
-like
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
(TLE), called crotalase, that is capable of clotting fibrinogen, leading to the secondary activation of plasminogen from endothelial cells. Although the venom does not activate
plateletPlatelets, or thrombocytes , are small, irregularly-shaped anuclear cells , 2-3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is between 8 and 12 days...
s, the production of
fibrinFibrin is a fibrous protein involved in the clotting of blood, and is non globular. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site.Fibrin is made from fibrinogen, a soluble plasma glycoprotein that is synthesised by the liver...
strands can result in a reduced platelet count, as well as the
hemolysisHemolysis —from the Greek Hemo-, Greek meaning blood, -lysis, meaning to break open—is the breaking open of red blood cells and the release of hemoglobin into the surrounding fluid ....
of
red blood cellRed blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen to the body tissues via the blood. They take up oxygen in the lungs or gills and release it while squeezing through the body's capillaries. The cells are filled with hemoglobin, a...
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 peptidePeptides are short polymers formed from the linking, in a defined order, of α-amino acids. The link between one amino acid residue and the next is called an amide bond or a 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 terrificusCrotalus 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
necrotizingNecrosis is the premature death of cells and living tissue. Necrosis is caused by external factors, such as infection, toxins , or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
, mildly
proteolyticProteolysis 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
phosphodiesteraseA 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
bradykininBradykinin is a peptide that causes blood vessels to enlarge , 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
hypotensionIn physiology and medicine, hypotension refers to an abnormally low blood pressure. This 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 opposite of hypertension, which is high blood...
.
Klauber (1997) describes 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.
CroFabCroFab™ 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
WyethWyeth, formerly known as American Home Products , was one of the largest pharmaceutical companies in the world. The company is based in Madison, New Jersey...
'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.
External links