RE: NANFA-- Freckled Madtom Eating Behavior

Hoover, Jan J ERDC-EL-MS (
Wed, 24 Mar 2004 08:18:25 -0600

John writes:
>>>I have noticed a behavior in my Freckled Madtoms that is probably more
widespread amoung Ictalurids. They don't seem to see the food that is
placed out for them. Bright red bloodworms are passed right by unless
their wiskers brush them. Then in a flash the worm is gone. I guess
the scent of the worm brings the catfish out but they don't seem to see
the food. Am I correct in my interpretation of this behavior? Is their
"sight" used to detect predators only or given their nocturnal
tendancies, is the use of sight not used much at all?

Jan responds:

I have seen similar behavior in least and brindled madtoms and your
interpretation sounds good to me. Its difficult to know how a fish
perceives its environment. For example, conventional wisdom indicates that
paddlefish and sturgeons are not strongly sight-oriented but recent work
shows morphologically well-developed eyes with diverse and distinctive rod
and cone cells. Possibility exists for high-contrast vision, color vision
(perhaps), and sufficient image formation for visual feeding.

On a related topic - the latest issue of "Natural History" has an article on
fiddler crabs that is fascinating! It describes the new field of "visual
ecology" - the science of seeing and interpreting the world through the eyes
of the organism rather than the human observer. Fiddler crab researchers
have developed a crab-cam that simulates crab vision which is very different
than you might imagine (i.e., ground-level objects are seen as a band around
aerial objects, with closer objects appearing smaller than objects at a
distance). It would be neat (and I would guess simpler) to do the same for
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