Posted by: salamandercandy | December 19, 2005

Why salamanders are not candy

There are many reasons why amphibians are cool. One particularly fascinating thing about them is their various wacky skin secretions. Lacking structural defenses, like claws, fangs, scales, or spikes, many amphibians have evolved chemical defenses. Skin glands squirt these substances onto potential attackers. Interesting amphibian chemicals include:

Poisons. The most famous toxic amphibians are the poison-dart frogs of Latin America. Choco Indians use these frogs to make deadly hunting weapons. Closer to home, the rough-skinned newt of the Pacific Northwest is also quite poisonous, full of the same toxin found in puffer fish, and only garter snakes are resistant enough to snack on these salamandrids. Poison-dart frog toxin acts by opening the sodium channels in the nerve cells, and newt toxin acts by blocking these same channels. So, in theory, you could eat the right combination of frogs and newts and be okay. But I wouldn’t recommend it.

Drugs. You may have heard of toad licking, which (if it’s the right toad), produces a psychedelic effect. Then there’s sapo, a drug derived from the giant waxy monkey tree frog, that’s used by Amazonian Indians for increased hunting proficiency and perhaps recreationally. Cane toads, when attacked, shoot a cocktail of cardioactive drugs out from enormous glands on the side of their head. I do not advocate the use of amphibian-derived drugs to alter your mental state, but it’s just neat to think about what they can do. No one ever gets high from licking a mouse or a sparrow.

Antimicrobials. Part of my own research is on the evolution of microbe-killing molecules (peptides) produced by frogs. These are extremely diverse and potent substances, active against bacteria, viruses, and fungi. Some are evolutionarily related to other interesting peptides, like the putative active ingredient in sapo, mentioned above. Frog extract has been traditionally used as medicine in places like East Asia, and these substances could be developed for new therapeutic applications, if we can keep amphibian species from disappearing before they can be studied.


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