Wilderness Underfoot: The catfish, a master of the senses

StoryImage( ‘/Images/Story//Auto-img-114910036623421.jpg’, ”, ‘Here, kitty kitty – The channel catfish, Ictalurus punctatus, is found in freshwater throughout our state. All catfish have “whiskers,” which some people mistakenly believe are stingers, though these sensors really aren’t dangerous at all. On the other hand, the pectoral and dorsal fins are armed with sharp spines that deliver painful jabs if a fish isn’t handled carefully.’);

From head to tail, this fish is outfitted with a remarkably powerful set of sensory organs

You probably couldn’t tell by looking at it, but the catfish is one of the most “wired” of animals when it comes to the senses. Readily identified by the whiskers, or barbels, for which it earned its feline name, this fish is built to receive sensory input from its environment.

To begin with, its trademark barbels are actually sensitive organs capable of feeling and tasting as the fish forages through sand, mud and vegetation. A catfish’s sense of taste doesn’t stop with the barbels, however. This fish is just loaded with taste buds, thousands of them, spread across every inch of its body. Whatever it touches, it can taste.

Along with the sense of taste comes an incredible sense of smell. The catfish might be more aptly called a “bloodhound fish.” It has an unusually high number of smell receptors in its nostrils, and as water flows through them, these sensors can detect odors at one part per billion. This is all the more amazing when you consider that a drug-sniffing dog needs at least 10 parts per billion to detect odors.

And then there’s the matter of hearing. While you can’t see fish ears, they do have them. The catfish belongs to a lineage—which includes suckers and minnows—that is endowed with exceptional hearing in the low frequency range, below 4,000 Hz. Its body is the same density as water, so sound waves pass right through the flesh. The waves are amplified by the fish’s bladder, then transmitted to special bones in the ear. Catfish farmers claim the fish can hear footsteps from long distances and will rise to the top of the water in frenzied anticipation at feeding time.

The sense of touch in catfish is excellent, but it is improved by this fish’s smooth skin and lack of scales. And to further enhance both its hearing and touch, this fish’s body has lateral lines with tiny sensors capable of detecting low-frequency vibrations that are too subtle for it to feel or to hear with its inner ears. It relies on these sensors to detect the presence of other catfish, as well as prey and predators. The lateral lines can even pick up electrical stimulation such as the microcurrents transmitted by other underwater organisms.

Typically, animals with such advanced senses are compensating for miserable eyesight, but not so with the catfish. Although different species have varying ranges of vision, most can see quite well—including the channel catfish, found in our own region.

From the May 31-June 6, 2006, issue

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