Steven Eadie, age 11, of Pierrefonds, Ouebec, Canada, for his question:
How does poison get into a snakes fans?
A snake's poison is a special kind of saliva, or spit. Its purpose is to paralyze protesting victims and the deadly stuff calls for very careful handling. One, it must be kept where it cannot harm the snake. Two, a fool proof system must be used to inject it into the proper party. How venomous snakes succeed is a remarkable story of adaptation which means solving problems by making adjustments.
This story began ages ago, when ancestral snakes embarked on a different life style. Scientists suspect they were long, low down lizards with stubby legs. For reasons known only to themselves, they took to living in burrows and crawling on their stomachs. As usual in such cases, their neglected legs gradually withered and disappeared.
The snakes were prepared for legless locomotion, but eating became a problem. Their menu is meat, swallowed alive. With no claws, hands or arms it was quite a challenge to grab and swallow a squirming dinner. All snakes developed remarkable stretchable jaws. This made it possible to swallow enormous helpings. But it did not help to hold a sprightly victim who refused to co operate.
Various species solved this problem in different ways. The boa type learned to coil around his captive. A little pressure made it impossible for the poor creature to inhale and he soon suffocated. Another group of snakey characters developed venoms to subdue their protesting victims. Maybe the first one started with stinging, corrosive saliva. However, strong, poisonous mixtures brought more success, though only to the snake with a built in system to poison his victim without hurting himself.
The rattler manufactures and stores his deadly venom in glandular sacs, located in the jaws just above his fangs. Each fang is a highly specialized hollow tooth, rooted in a venom sac and having a tiny hole in the tip. The set up resembles a hollow hypodermic needle attached to a syringe. When the rattler strikes, the fangs sink deep and the pressure pushes venom down the tubes, to be injected into the fleshy bite.
One more adjustment was needed to save the rattler from himself. His fangs are long and very sharp. If they hung straight down, old buzzy tail might bite himself accidentally. This does not happen because the fangs are mounted on moveable hinges of bone. They move down to strike and fold up into the roof of the mouth when not in use.
The coral snake has a simpler system to deal his deadly venom. This fellow wears gaudy garters of red, yellow and black and inhabits the southern shores and borders of the United States. His toothy fangs are not long, hollow needles. They are rather stubby and each has a groove down the back. When he strikes, venom oozes along the grooves and some may enter the jab wounds. However, some of the deadly stuff often oozes away and the coral snake has to nag and knead it into the victim's flesh. Obviously this system is clumsy and inefficient.