Eastern Diamondback Rattlesnake

Crotalus adamanteus

Common names: eastern diamondback rattlesnake, eastern diamondback.

Crotalus adamanteus is a venomous pitviper species found in the southeastern United States. It is the heaviest (though not longest) venomous snake in the Americas and the largest rattlesnake. No subspecies are currently recognized.

Description

The largest rattlesnake species, the maximum sizes reported are 244 cm (8.0 ft) (Klauber, 1972) and 251.5 cm (8.25 ft) (Ditmars, 1936). One captive specimen weighed over 26 pounds (12 kg). However, the stated maximum size has been called into question due to a lack of voucher specimens (Jones, 1997).

Specimens over 7 ft (210 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 ft (240 cm) specimen, dead or alive. The reward was never claimed. He did receive a number of 7-foot (2.1 m) specimens and some 8-foot (2.4 m) skins, but said that such skins can be taken from a 6 ft (180 cm) snake.[2] 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 3.5–5.5 ft (110–170 cm),[7] 84–183 cm (2.8–6.0 ft) are given.[8] One study found an average length of 170 cm (5.6 ft) based on 31 males and 43 females.

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. On the head, the rostral scale is higher than it is wide and contacts 2 internasal scales. There are 10-21 scales in the internasal-prefrontal 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 scales, the first of which is in broad contact with the prenasal, and 15-21 (usually 17-18) sublabial scales.