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Name: Silver P.
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 2/23/2003

During some research on the man o' war (Physaliia physalis), I found that its pneumatophore/float is filled with argon. Why would such a rare gas be found in an animal? How did it get there? I heard that this float can be deflated by the sun. Does argon react in some special way with ultraviolet rays?

Your skepticism is very appropriate. In reverse order: Argon does not react with ultraviolet light from the Sun in any special way I know of. The bouncy of a jelly fish could certainly be altered by the heat from sun light. In particular, the product of the Pressure and Volume, P x V = n x R x T where n = number of moles of gas, T is the temperature in kelvins (K), and R = gas constant = 0.0825 liter atm./moles kelvin.

I too found the claim that its bladder is filled with argon, but none of the web sites actually presented any data to support that claim. The atmospheric and sea water abundance of argon is: 9300 and 0.45 ppm. Given the large population of these jelly fish, it is hard to see how they could extract argon from the atmosphere in sufficient amounts to alter its bouncy. I would like to see some mass spectral data that shows that the claim is true. Because if it is true, there is a fertile field of research for selective semi-permeable membranes out there!!

Vince Calder

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