Crotalus adamanteus
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| Crotalus adamanteus Palisot de Beauvois, 1799 |
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Common names: eastern diamondback rattlesnake, eastern diamond-backed rattlesnake,[2] more.
Crotalus adamanteus is a venomous pit viper species found in the Southeastern United States. This is the heaviest venomous snake found in the New World and the largest rattlesnake. No subspecies are currently recognized.[2]
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[edit] Description
The largest rattlesnake species, the maximum sizes reported are 244.0 cm (Klauber, 1972) and 251.5 cm (Ditmars, 1936). One captive specimen weighed over 12 kg. However, the stated maximum size has been called into question due to a lack of voucher specimens (Jones, 1997).[3]
Specimens over 7 feet (213 cm) 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 8-foot (243.8 cm) 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 (182 cm) snake.[4]
The average size is much less: lengths of 106-167 cm,[5] 84-183 cm are given.[6] One study found an average length of 170 cm based on 31 males and 43 females.[7]
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 id 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.[3]
[edit] Common names
Eastern diamondback rattlesnake, eastern diamond-backed rattlesnake,[2] eastern diamondback, Florida diamondback, Florida rattlesnake, lozenge-spotted rattlesnake, southeastern diamondback rattlesnake, southeastern diamond-backed rattler, southern woodland rattler, water rattlesnake.[7]
[edit] Geographic range
Found in the southeastern United States from southeastern North Carolina, south along the coastal plain through peninsular Florida to the Florida Keys, and east along the Gulf Coast though southern Mississippi to southeastern Louisiana. The original description for the species does not include a type locality, although Schmidt (1953) proposed that it be restricted to "Charleston, South Carolina" (USA).[1]
[edit] Conservation status
While being evaluated as a species of Least Concern, this species has been declining for years due to habitat destruction, hunting and persecution. It has been suggested that, because of the decline of these snakes, the rabbit population in Florida is on the rise.
[edit] Habitat
Inhabits upland dry pine forest, pine and palmetto flatwoods, sandhills and coastal maritime hammocks, long-leaf pine/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 gophers and gopher tortoises during the summer and winter.[3]
[edit] Behavior and Reproduction
Eastern diamondbacks can live beyond twenty years, but life expectancy is typically shorter because of hunting and human expansion. Solitary outside of mating season they are one of the more aggressive species found in North America because they rarely back away from confrontation. When threatened they usually coil and shake their rattle to warn aggressors- they stumbled upon something dangerous. There is suspicion that some rattlesnakes (and the diamondback in particular) which generally live around populated areas do not rattle as often because it leads to the snake’s discovery and consequent destruction. However, there is little available evidence of this hypothesis.
The snake is a poor climber and primarily hunts small mammals, but will also feed on birds, small reptiles and amphibians. They may even hunt rabbits. They hunt (or ambush prey) at night or early morning using a type of infrared sense prominently found in pit vipers. Hawks, eagles, and other snakes can prey on young or adolescent diamondbacks.
Rattlesnakes, including C. adamanteus, are viviparous. Gestation period lasts six or seven months and broods 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.
[edit] Venom
This species has the reputation of being the most dangerous venomous snake in North America.[8] 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.[7]
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.[4] It has a very high venom yield: an average of 400-450 mg, with a maximum of 858-1,000 mg.[9] Brown (1973) 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.[10] The estimated human lethal dose is 100-150 mg.[9]
The venom contains a thrombin-like enzyme (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 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 (Hasiba et al., 1975). Nevertheless, the venom does exhibit high hemorrhagic activity (Minton, 1974). It also contains a low-molecular-weight basic peptide that impedes neuromuscular transmission (Lee, 1972) that can in theory lead to cardiac failure. 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, mildly proteolytic and containing large phosphodiesterase fraction. It stimulates the release of bradykinin that can result in severe pain, as well as profound, transient hypotension. [9]
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.[4]
CroFab and Wyeth'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.[9]
[edit] See also
[edit] Cited references
- ^ a b McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- ^ a b c Crotalus adamanteus (TSN 174309). Integrated Taxonomic Information System. Accessed on 28 November 2006.
- ^ a b c Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
- ^ a b c Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. University of California Press, Berkeley. ISBN 0-520-21056-5.
- ^ U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN 0-486-26629-X.
- ^ Conant R. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Second Edition. First published in 1958. Houghton Mifflin Company Boston. 429 pp. 48 plates. ISBN 0-395-19979-4. ISBN 0-395-19979-8 (pbk.).
- ^ a b c Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.
- ^ 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. ISBN 0-394-50824-6.
- ^ a b c d Norris R. 2004. Venom Poisoning in North American Reptiles. In Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
- ^ Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN 0-398-02808-7.
[edit] External links
- Species Crotalus adamanteus at the Species2000 Database.
- Eastern Diamondback Rattlesnake at Florida Museum of Natural History. Accessed 2 March 2007.
- Eastern Diamondback Rattlesnake at Orlando, FL Rat & Mouse Control. Accessed 2 March 2007.
- 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.
