Re: NANFA-- Land fish
Bruce Stallsmith (fundulus_at_hotmail.com)
Sun, 10 Mar 2002 15:13:46 -0500
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Thanks Scott, I thought I had that link bookmarked but 'twas not so. I would
doubt that _marmoratus_ does much cutaneous respiration, because even they
are covered by a slime coat like other fishes which would slow down gas
exchange. A better bet would be to look for buccal (mouth) vasculature that
can perform enhanced respiration, as well as the gills themselves which are
a good bet if they're kept damp. Amphibians can more or less respire across
their skins, but not all are good at doing that in water. Bullfrogs can do
about 35% of their gas exchange in air across their skin if it's wet, one
reason they have relatively small lungs. The larger salamanders like
hellbenders have greater capacity for aquatic cutaneous exchange although I
don't know the details; that's a major reason you find them in cold waters,
because cold water can hold more dissolved oxygen (and their metabolisms are
slower, too). I know one older reference for this, an article by Robert
Guimond that appeared in American Zoologist (I think) in 1973. It was the
summary of his doctoral work at the Univ. of Rhode Island on mudpuppy
respiration in particular. He set up an experiment where he put a mudpuppy
in a large aquarium of water, covered the top with about 15 cm of a
hydrophobic oil lighter than water, and observed the mudpuppy's behavior. It
could always survive for weeks at a time without access to atmospheric air,
and as I recall Guimond concluded that their small lungs are effectively
vestigial, really useless. Nowadays he teaches A&P at the University of
Massachusetts in Boston if anyone wants to track him down...
--Bruce Stallsmith
Huntsville, AL, US of A
>http://www.bsi.vt.edu/rivmar/#figure
>
>Some killie people, have been hurruphing that it is only classified as
>endangered in Florida because it is seldom found in conventional surveys.
>Tossing a piece of food on a string in front of a crab hole evidentally is
>not standard procedure. I don't know how common mangrove swamps are.
>
>Andy Borgia made some neat observations about these fish last year on this
>list.
>
>Dan Fromm, in a hobby article somewhere (probably an old JAKA), cited
>someone who suggested that the Rivulus' ability to stay out of water was
>enhanced by a relatively large number of blood vessels very near to the
>skin
>which may have aided in oxygen absorption. Are there blood vessel rich
>amphibians who do this vis-a-vis the water?
>
>All the best,
>
>Scott
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