Were it not for the pinkish blood vessels, you could see through the tine translucent body of an Ozark cavefish. The fins resemble threads of glass. The flattened head lacks eyes, as if the fish were awaiting completion by its creator.
The cavefish has no eyes, because in the underground streams it inhabits, there is no light by which to see. Special sensory organs cover the head, body and fins, permitting it to feel its way around in its eternally dark home.
The historic range of the Ozark cavefish included 24 Ozark Mountain caves in Arkansas, Missouri and Oklahoma. That range has shrunk to 21 caves, including seven in northwest Arkansas.
A very low reproductive rate is one reason for their rarity. Cavefish may be 16 years old before first spawning. Only 20 percent spawn each year. Twenty to 25 eggs are incubated in the female's gill chamber until hatching.
Illegal collection by pet dealers is a great threat to these unusual fish. Removing even small numbers can seriously affect a population for years and may even destroy it.
Groundwater pollution from sewage, livestock wastes and toxic compounds is another threat, one compounded by growing human populations and industrial development in the Ozarks.
Ironically, the Ozark cavefish's life cycle is linked to that of another imperiled species, the gray bat. A cave's food supply depends on an outside energy source. The largest Ozark cavefish populations occur in caves used by the gray bat, where the bat's guano forms the cave's primary energy source. A reduction in bat numbers could cause a decline in the cavefish population.
By protecting the habitat of a few cavefish, we are also protecting our own habitat, for much of the drinking water in areas where Ozark cavefish live is groundwater. Ozark cavefish are indicators of environmental health. If they start disappearing, something is wrong. By protecting one resource precious to some of us, we are guarding another resource very precious to all of us.