for National Geographic Kids News
Do your nightmares ever include two-headed monsters? Storybook dragons and serpents may have a basis in reality. A farmer in Spain captured a two-headed snake last month, and scientists are eager to study it.
"Two-headed snakes are rare, but they shouldn't be looked at as freaks," said Gordon Burghardt, a herpetologist at the University of Tennessee. Herpetologists study reptiles like turtles, snakes and lizards. Each two-headed animal is highly individual, and has its own personality and reasons for doing things the same as any other creature, he said.
The snake in Spain is lucky it was captured; there is no way it could survive on its own in the wild.
Just imagine all the problems you would have if you had two heads. It would be as if you had to get one of your brothers or sisters to agree with every decision you madewhat to wear, what to eat, when to eat, what to watch on television, what site to visit on the Internetall the time, every time.
That's how it is for a snake with two heads. First the two heads have to decide they're both hungry at the same time, and then they have to agree to pursue the same prey. Then they might fight over which head gets to swallow the prey. To make it even more complicated, since snakes operate a good deal by smell, if one head catches the scent of prey on the other's head, it will attack and try to swallow its second head.
"They also have a great deal of difficulty deciding which direction to go, and if they had to respond to an attack quickly they would just not be capable of it," said Burghardt.
Two-headed snakes raised in captivity can do quite well though. Burghardt had a two-headed black rat snake that lived to be almost 20 years old. Arizona State University was home to a two-headed king snake that was found in the desert as a baby. The snake lived for close to 17 years at the university. Thelma and Louise, a two-headed corn snake that lived at the San Diego Zoo until its death, had 15 normal babies.
Snakes born with two heads happen the same way Siamese twins are born to humans. A developing embryo begins to split into identical twins but then stops part way, leaving the twins joined. The point at which the embryo stops separating varies, and just as Siamese twins can be joined at the head, breast, or hip, the same is true for snakes.
The king snake at ASU had two heads supported by separate necks, and they shared a stomach. The two-headed black rat snake that lived for close to 20 years at Burghardt's lab each had a complete throat and stomach. The ladder snake in Spain has two completely separated heads that join the body at about neck level. The two heads on Thelma and Louise were quite close together.
"If the two heads are very close together it's going to be much more difficult for them; with more separation, they can act a little more independently," Burghardt said.
The two-headed snake found in Spain is a non-venomous ladder snake. It was about two months old when it was found, and around 8 inches (20 centimeters) long. It is now on its way to its new home at the University of Valencia, where biologist Enrique Font will study it.
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