Biomechanics of Information

[wolfhnd]

EVANSTON, Ill. --- The hunting strategy of a slender fish from the Amazon is giving researchers more insight into how to balance the metabolic cost of information with the metabolic cost of moving around to get that information.

The fish hunts while its body is tilted downward, which, much like standing up on the pedals of a bicycle while going downhill, causes more than twice as much resistance to movement than if the fish were swimming with no tilt. However, this posture allows the fish to scan a wider area of fresh water and encounter more prey. The researchers found that the increased cost of movement caused by body tilting was more than counterbalanced by increased sensory performance. Past a certain angle of tilt beyond what was naturally observed, the additional cost of moving with the body tilted was greater than the energy gained by sensing more prey.

http://www.northwestern.edu/newscenter/ ... civer.html

[Marshall]

Thanks for that curious item. The article says that the fish hunts at night and, instead of seeing its prey with its eyes, it generates an electric field with its body. Like an electric eel but much weaker. It senses insect larvae and other prey electrically---it feels a potential meal with its electric field.

Wikipedia says the black ghost knifefish has electric sensors all down the length of its body.

I suppose that larvae and other fish might be more conductive than plain water. Could that be right? If so, then the prey would "short out" the electric field and the hunter would feel that "short" and would strike in the indicated direction.