Physaliia physalis and Argon
Name: Silver P.
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!!
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Update: June 2012