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Harmless poison frogs, not so hot lightning, recycled humans

Q: I was just reading your article on poison dart frogs from South America, and wondered, when kept in captivity, does the poison in these frogs disappear after a while? I've seen them in the zoo and got curious if those frogs could still kill a human even if they don't have the same diet as in the wild. (Forrest)

The extremely toxic P. terribilis, who eats pure poison [Charles W. Myers, American Museum of Natural History]

A: The poison-dart frog sits like a lethal golden statue on a large bronze leaf. Leaf veins branch like a roadmap beneath her tiny body. Treat her with respect. Threatened, she oozes onto her skin an alkaloid poison (batrachotoxin) — venom 250 times more toxic than strychnine. The poison can kill a human easily and quickly once in the blood stream.

A wild frog keeps its poison in skin glands for years ready for trouble. "So, a wild-caught frog will, in captivity, remain noxious and toxic for years," says John Daly, Scientist Emeritus, Laboratory of Bioorganic Chemistry, National Institutes of Health. Diet makes no difference because the poison, gathered in the wild, is stored and ready, like a loaded cocked pistol.

Fortunately, zoo poison-dart frogs have no chance to get the poison. They are born in the zoo and raised on diets that do not contain alkaloids.

The wild frog takes up the poison, "like vitamins," from a proper diet of ants, beetles, and foods he eats in the jungles of Western Colombia. This is where the three species of true poison-dart frogs dwell.

When I wrote the article that you refer to, we didn’t know what insect provided the frog’s poison. Now we do.

John Daly and his colleagues have solved that mystery. We, however, must wait until they publish their manuscript. "I can, at this point, tell you only that it is not an ant," says Daly. Stay tuned.

Further Reading:

WonderQuest: The most poisonous creature on Earth could be a mystery insect

Myers, C.W., J.W.Daly, and B. Malkin. 1978. "A dangerously toxic new frog (Phyllobates) used by Emberá Indians of western Colombia, with discussion of blowgun fabrication and dart poisoning." Bulletin of the American Museum of Natural History 161 (2): 307-366, 28 figs. + color pls. 1-2.

Not so hot lightning

Q: Lighting is supposed be three times hotter than the sun. Since the lighting flashes are closer than the sun how come we don’t feel the heat when it flashes? (George)

Lightning pales beside the Sun as a heat source [NOAA and SOHO]

A: Lightning can heat nearby air up to even 10 times the temperature of the Sun’s surface. Actually, the Sun’s surface isn’t so hot — some welding torches are hotter. ( The Sun’s center, though, is 2500 times hotter: 15 million degrees Kelvin compared with 6 thousand degrees.)

It isn’t the Sun’s temperature, however, that accounts for the heat we feel on Earth. Rather, it’s her size. The Sun has a surface area a hundred million billion times the surface area of a typical lightning bolt. We receive only 1 billionth of the Sun’s energy. Even so, Earth gets much more energy from the Sun than from a lightning bolt over the same time period — a hundred million times more energy (calculation).

Of course, close to the lightning strike, we can get blazing hot. Lightning striking a tree can set it afire. The distance to the target, however, must be small for us to feel the heat because lightning’s radiant energy pales compared with the Sun.

Further Reading:

HyperPhysics by Rod Nave: Heat radiation

HyperPhysics by Rod Nave: Lightning flashes and strokes

NOAA: What is lightning?

Recycled humans

Q: Does earth get heavier because the human population keeps increasing and the number of living things on earth keeps getting larger? If not, why not? (Jenny, Sydney, Australia)

Earth recycles her mass [JSC/NASA]

No, increasing populations don’t make Earth heavier because new creatures are made of atoms already present on Earth. We are recycled products. Many atoms in our bodies are nearly as old as the Universe, cycling and recycling through countless hosts — some animate and others inanimate.

I breathe a lungful or eat a mouthful of atoms. Some atoms stay to become a part of me or, eventually, my offspring. Others return to Earth either as waste products or, finally, as a body. I only borrow "my" atoms for a while.

By the way, Earth’s mass does increase each year by 44,000 tons (40000 metric tons). Interplanetary dust drifts down upon us and remains. But that’s just 0.000003 of one percent of the mass of Earth. Negligible.

Further Reading:

WonderQuest: Heavy Earth

(Answered July 9, 2004)