Adrian said:

> "The Law of Odor-Search Behavior."
> Quite simply put, that law is the simple fact that an animal can find
> a source of odor ONLY by coming in from downwind (or from down
> current - in the case of fish and the like).

Not to nit-pick, but the above otherwise reasonable statement does not
address the case of "no wind" conditions.  The "only" is therefore a tad strong.

With "no wind" there is a certain radius for an "odor" where particles that can
be detected as "the odor" is distributed by what comes down to "Brownian motion"
of the air due to temperature alone.

For example, take a sealed box, and put some PDB crystals into it for a day.
No matter where you put your sensor, the PDB odor will be detected.
Once you start "sniffing", you can find the actual PDB crystals by strength
of the odor alone.  The easiest example of this would involve a stack of supers,
each with an "upper entrance" hole, each plugged with a cork.  The "sensor"
would be your nose, sniffing at each hole as your open them one at a time.

Once an animal chances upon even a faint odor, they can move about and
find the source through a mix of random moves and subsequent "sniffs" to
decide if the odor is stronger of weaker, in a olfactory game of
"blind man's bluff".  No air motion is required to play.

Does it work in an absolute sense?  Sure.  Insect mating and activity is
often studied in sealed terrariums lacking ventilation, and hence, airflow.

What's the best example of an ecosystem with no wind most of the time?
A cave.  One only has "wind" in a deep cave when barometric air pressure
changes are in progress.  Once the pressure equalizes between the cave and
the surface, there is no "breeze", "upwind", or "downwind" in dead-end
chambers and passages.

Caves also contain pools of water with no current for an aquatic example.
Some have weird-looking fish with no eyes.  (If you come upon such a pool
and you are not with an experienced caver, note that getting wet is often fatal
for amateur spelunkers, so don't even think about wading across, no matter
what is just across the water.)

                jim (who recently dead-ended in a maze of twisty passages,
                               and thought briefly about airflow in caves)