This may or may not be fact, but it might be close.
From various nebulous sources there has been news
lately of a long extinct ancestor of our modern-day
shrimp. This was a fresh water creature and was
distantly related to a large family of exoskelitials.
Many of our present day shrimp type creatures are
descended from this long 'lost' common source. The
major difference was that they absorbed oxygen
through the sides of their abdomens (as do most
mayflies today). The major family split and this
'Airos-absorbicus' went on as did the Neanderthal.
These small invertebrates were indigent to the
streams and lakes where many of our trout specie
of today are now found. Over the millions of years,
due to the high fat content of these shrimps, the
trout fared extremely well and proliferated. This
was in direct relation to the numbers of shrimps.
Time was on the side of the trout though, in the
end he was the perserverer.
As the numbers of shrimps dwindled due to the growth
rate and exhortbisism of fish, the shrimps went into
overdrive and, as is often the case in nature, their
population exploded. However this only offered more
food for the trout and caused the ultimate total
demise of the whole class of shrimps.
This is of importance to us fly-fishers because of
the deep-seated relationship of the 'shape' of the
now extinct shrimps. If one envisions our modern
shrimp, you will notice some similar elements of
build. They both had tails which turned down, a
thin body, and when at rest on the surface of the
water (air breathers, remember) the front claws
were help close together and hung down.
Over the eons our trout developed a keen instinct
for them and so solid is it that in thousands of
articulated tests, trout would often take an
artificial fly when it was attached to a shape
resembling those shrimp. This testing was performed
on the surface, in the surface, in mid-stream and
on the bottom. The tests, done on secret for many
years now, have shown that both day and night, all
seasons of the year and at any stage on the trouts
development, the 'shrimp-shape' often will elicit
an uncontrolled feeding response in trout of all
ages, specie and size.
This should put to rest some of the nay-sayers of the,
"How the hell do ya account fer the damn hook on yer
flies?" Not only does the hook look remarkably like
the now 'Shrimpus-extinctus,' it allows the tied fly
to be presented almost as if it had a dab of bait
attached. ~ James Castwell