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How come some snakes could kill people?
Asked by: Chelsea Murphy
School: Owego Elementary School
Teacher: Mrs. Elliker
Hobbies/Interests: Lacrosse, soccer and gymnastics
Career Interest: Teacher
Answer from Dale Madison
Professor of Biology, Binghamton Univeristy
University of Maryland, College Park
Ecology, Fitness, Landscaping, Craftsmanship, WelfareVolunteer
Wife: Diane; four children: Ryan, Nathan, Lisa and Tracy
This question raises several interesting things about snakes. First, snakes kill for two reasons, to obtain food and to protect themselves. People are not included in the normal diet of any snake species, and so when a person is killed, it is usually because the snake is trying to protect itself or mistakes a person for a prey. Second, snakes that kill prey larger than themselves do so by suffocating them or poisoning them; smaller prey are simply grabbed and swallowed alive. Snakes that suffocate their prey must hold onto them long enough to coil around them and shut off their air supply. Multiple rows of teeth curved backward toward the throat give the snake a bite that is very difficult to get away from. Snakes that inject toxic saliva into their prey either do so with a quick stab (like rattlesnakes and copperheads) or hold onto the prey and work the toxic saliva gradually into the bite wounds (like coral snakes). Quick stabs are used by snakes that prey on animals that could injure or kill the snake during an attack. A rat's front teeth are a formidable weapon, and it is best if the snake can stab quickly and then move away and let the toxin do the killing. To be effective, most toxins must be fast-acting, otherwise injected prey may die too far away to be found and eaten by the snake. Many toxins are therefore so potent that one injection can eventually kill an animal or a person many times larger than could ever be swallowed by the snake. So, what snakes end up killing people? Only a few snake species can kill a person by suffocation, the two primary species being the Anaconda of South America and the Reticulated Python of Asia. The former can have a girth the size of a man's waist and weigh as much as 500 pounds. The latter is more slender but longer, measuring up to 28 feet. Only a few reports exist of these snakes killing and swallowing a person, and even these accounts are questionable (Google search: Man-eating snakes). By far, most human deaths occur from poisonous snake bites, about 40,000 per year world-wide 50 years ago, but the number today is lower because of disappearing natural habitats and declining numbers of poisonous snakes. The highest death rate is in southeastern Asia. In the U.S., the species causing the greatest number of deaths is the Western Diamondback Rattlesnake. Some of the deaths occur as a result of people trying to tease, collect venom from, or kill the snakes for trophy. Other deaths occur because an unsuspecting person gets too close to the snake, and the warmth of the person's body triggers a strike. Apparently, rattlesnakes that use heat sensing organs to detect potential prey can't discriminate between the warmth of a moving hand or a small mammal like a kangaroo rat. If no antivenom is administered, or if nothing is done to reduce the entry of the toxin into the person's blood stream, death from one bite of a rattlesnake is likely. And so snakes may kill people not for food but because they feel threatened by people or they mistake a person's hand or foot for their normal prey. It is best to just leave all snakes alone and be wary in habitats occupied by poisonous snakes.