Crotalus

Crotalus is a genus of venomous pit vipers found only in the Americas from southern Canada to northern Argentina. The name comes from the Greek word krotalon, which means "rattle", referring to the rattle on the end of the tail. There are currently 29 species recognized.
Description
Members of this genus range in size from only 50-60 cm to over 150 cm. Adult males are slightly larger than females. Compared to most snakes they are heavy-bodied, although some African vipers are much thicker. They are recognized by the rattle on their tail though some species do not have tails.
Feeding
Small species eat mainly lizards, while larger species first eat lizards when young, then start eating mammals when they become adults, like rabbits, squirrels, chipmunks, gophers, rats and mice, some also eat birds, other snakes and amphibians.
Predators
Humans are a threat to Crotalus, but other snakes like the Kingsnake, the Coachwhip, the Indigo Snake and the Racer are also threats. Birds like the hawk, the eagle, the owl, the raven and the roadrunner, and mammals like the coyote, the fox, the wildcat, the badger and the skunk are also threats
Venom
Almost all Crotalus venoms are hemotoxic, meaning that the venom destroys red blood cells, stops blood clotting,and damages tissue. Hemotoxic is very painful, and people who are bitten by a snake with hemotoxic don't always make a full recovery. Some species like Crotalus Scutalatus and Crotalus Tigris have a nuerotoxic venom, while neurotoxins are less painful they kill more quicker. Neurotoxins are also found in the venom of Cobras and mambas. The eastern diamondback rattlesnake (Crotalus Adamanteus) in some parts of its range may have a nuerotoxin in their venom as well as a hemotoxins.
Species
Eastern diamondback rattlesnake, C. adamanteus
Queretaro dusky rattlesnake, C. aquilus
Western Diamondback Rattlesnake, C. atrox
Mexican west coast rattlesnake, C. basiliscus
Santa Catalina rattlesnake, C. catalinensis
Sidewinder, C. cerastes
Cascabel, C. durissus
Great Basin rattlesnake, C. lutosus
Hopi rattlesnake, C. nuntius
Yellow rattlesnake, C. concolor
Grand Cayon rattlesnake, C. abyssus
Southern Pacific rattlesnake, C. helleri
Desert rattlesnake, C. dahli
Brazilian rattlesnake, C. terrificus
Aruba Island rattlesnake, C. unicolor
South American rattlesnake, C. cumanensis
Black spotted rattlesnake, C. vegrandis
Baja California rattlesnake, C. enyo
Timber rattlesnake, C. horridus
Mexican small-headed rattlesnake, C. intermedius
Autlan rattlesnake, C. lannomi
Banded rattlesnake, C. lepidus
Speckled rattlesnake, C. mitchellii
Black-tailed rattlesnake, C. molossus
Northern Pacific rattlesnake, C. oreganus
Mexican lance-headed rattlesnake, C. polystictus
Twin-spotted rattlesnake, C. pricei
Tancitaran dusky rattlesnake, C. pusillus
Red diamondback rattlesnake, C. ruber
Mohave rattlesnake, C. scutulatus
Neotropical rattlesnake, C. simus
Long-tailed rattlesnake, C. stejnegeri
Tiger rattlesnake, C. tigris
Tortuga island diamondback rattlesnake, C. tortugensis
Totonacan rattlesnake, C. totonacus
Cross-banded mountain rattlesnake, C. transversus
Mexican rattlesnake, C. triseriatus
Prairie rattlesnake, C. viridis
Ridge-nosed rattlesnake, C. willardi
References
Vipers