Rattlesnakes

RATTLESNAKES, subfamily Crotalinae, family Viperidae; there are more than 60 species, mostly living in America. Rattlesnakes received their name due to the presence of a rattle at the end of their tail, consisting of interlocking horny segments (see figure ^, which are remnants of the keratinized epidermis, not shed during molting. When the snake activates the rattle, a sound like that of a grinding wheel or a rustle is produced. Not all Crotalinae have a rattle; for example, it is absent in the copperheads (see Ancistrodon). As America was colonized and pigs were raised, which eat rattlesnakes, the number of the latter began to decrease. Representatives of the genus Crotalus: The rattlesnake, or forest rattlesnake - Crotalus horridus L. (see figure 2), up to 2 m in length (Mexico, western part of the U.S.); feeds on small mammals and birds, does not attack humans unless provoked. The terrible rattlesnake - Crotalus terrificus Laiir., lives in Florida and Brazil. Another genus of rattlesnakes is Sistrurus, whose species do not exceed 80 cm in length; their rattle is also small, they are less dangerous than Crotalus. The venom of Crotalus is rich in neurotoxin, which selectively acts on the nervous system. At the site of the bite, there is almost no reaction, except for a hemorrhagic edema of the wound; gangrene never occurs. The resorptive effect of the venom comes to the fore. The nervous system loses irritability, paralysis develops, and death occurs from paralysis of the respiratory muscles. If poisoning does not progress too quickly, inflammation of the liver, kidneys, and brain develops; the liver undergoes fatty degeneration. Among 1,959 people bitten by venomous snakes in Brazil, the highest mortality was caused by poisoning from the bite of Crotalus terrificus. The specific therapeutic agent is anticrotalic serum, obtained by immunizing horses with Crotalus venom. The polyvalent serum is also effective, obtained by immunizing a horse with pharmacologically different snake venoms - Lachesis and Crotalus ("serum antiophidique").

Figure 2. Forest rattlesnake - Crotalus horridus.