Southern Pacific Rattlesnake

Appearance

Adults are 24-55 inches in length.

The color pattern consists of a pale brown, gray-brown, or yellowish brown ground color overlaid with a series of large, dark brown dorsal blotches that may or may not have pale centers. The blotches are more diamond shaped, as opposed to those of ''C. o. oreganus'' that are more hexagonal, and are bordered by light scales. The tail rings are not clearly defined. In juveniles, the end of the tail is bright orange, but this turns to brown as the snakes mature. In adults, the base of the tail and the first segment of the rattle are brown. The postocular stripe is moderately to very clearly defined. In juveniles, this stripe is bordered above by a pale stripe, but as the snakes mature this turns to drab yellow or brown. A conspicuous pale crossbar is sometimes present across the supraoculars, after which the head is a uniform dark color. In some older snakes the head is mostly dark with almost no trace of the supraorbital crossbar, or none at all.

Naming

The specific name, ''helleri'', is in honor of American zoologist Edmund Heller.Southern Pacific rattlesnake, black diamond rattlesnake, black rattler, gray diamond-back, mountain rattler, Pacific rattler, San Diegan rattler. and Green rattlesnake

Defense

''Crotalus oreganus helleri'' has a highly toxic venom that is much like mojave toxin in the way it attacks nerve endings. It also contains myotoxins and hemotoxins and can easily give a fatal bite.
The venom from this snake also requires a much higher dose of Crotalidae polyvalent immune fab , an antivenom used to treat the bite of North American pit-vipers.