Spencer:
I was watching the discovery channel one day and they were discussing these extremely poisonous salamanders.
The poison found in in the granular glands of newts of the family Salamandridae is especially toxic, and was given the name tarichatoxin after its isolation in western newts of the genus Taricha. Tarichatoxin is biochemically identical to the water soluble alkaloid tetrodotoxin (anhydrotetrodotoxin 4-epitetrodotoxin, tetrodonic acid), or TTX, the third most potent non-protein neurotoxin known to exist. Upon entering the blood stream, TTX blocks the sodium channels of excitable membranes, causing paralysis in the nerves and muscles.
Tetrodotoxin is found in Japanese pufferfish and in several other poisonous animals including globe fish, sun fish, trigger fish, blue-ringed octopus, frogs of the genus Atelopus, seastars, xantid crabs, horseshoe crabs, numerous marine snails, flatworms, and sea squirts, with more species still being discovered.
It is thought that the toxin is acquired through the food chain from TTX-synthesizing bacteria. Through natural selection, pufferfish and other animals possessing TTX took advantage of a single-point mutation in their sodium channel that rendered them immune from the toxin. This enabled them to consume and adapt the poison to their systems without experiencing any ill repercussions.
Welcome livingunderworld.org - Hostmonster.com
In other words, for these animals, evolving the ability to use these toxins required only the aquisition of
resistance to toxic elements already available in their environments.
The big question the scientists were pondering was how did these salamanders become so deadly? They later discovered that a specific species of snake was hunting these salamanders for hundreds of years. Over time, the snake grew immunity to the salamandar's poison. This in turn caused the salamander's poison to become more potent and the cycle continues.
Many of the sophisticated adaptations we observe (the speed of the cheetah, for example, or the camouflage of stick insects) seem best explained as the results of this sort of 'arms race'. But there are other big questions, such as: "are bacteria of the genus
Vibrio really the source of TTX in salamanders; if so, how exactly do the amphibians aquire it; and how exactly do the bacteria produce it?"
The snake still eats these extremely poisonous salamanders because it has a pretty good immunity towards them. After eating them, they don't die, they are merely paralyzed for a few hours from the effects of the poison.
In my youth, I was (regretably) often willing to injest substances which could easily be regarded as 'poisonous', with the express intent of achieving a similar effect. I now limit my deliberate intake of toxins to caffeine, with the express intent of counteracting a paralysis which, as I get older, seems more and more to be my natural, unmedicated state.