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August 01, 2012

Jazzin' Instrumentals: Bowfin


In part 1 of our Jazzin’ at the Shedd violin summit last week, you met the fiddler ray. In part 2, we introduce the complementary follow up: the bowfin.

You can find bowfins in the fossil record from 100 million years ago. You can also find them in Illinois rivers today, including the Des Plaines, Fox, Rock and Vermillion; in Lake Michigan around Green Bay; and in the Local Waters gallery at Shedd.

Amia calva is a handsome fish, 18 to 24 inches long, with two striking features: an unusually long dorsal fin, which runs from midback to the caudal fin, and a velvety black, gold-rimmed “eye spot” at the base of the tail, which covers its back in another way. Concealed in vegetation as it waits to ambush prey, the bowfin only has to flick its facelike tail to fake out anything hunting it.

The bowfin is considered a relict species because of its “primitive” skeleton that is part bone and part cartilage and its double skull, consisting of a bony outer layer and cartilage inner layer. More modern fishes have completely bony skeletons. The bowfin is the only living member of an ancient family of fishes, the Amiidae, that in turn is the only remaining family in the order Amiiformes, whose heyday was in the Mesozoic.

Obviously, the bowfin is a very successful species, too.

For starters, bowfins can use their gas bladder as a simple lung to breathe air, enabling them to live in warm, sometimes stagnant shoreline waters where other large predatory fishes cannot. That means when the temperature goes up and the dissolved oxygen level goes down, the bowfin has easy pickings of insects, crayfish, frogs, turtles and other fishes without much competition. Having indiscriminate tastes—whatever animal life it can catch—doesn’t hurt its survivability, either.

Being able to breathe air also allows bowfins to sit out droughts by burrowing into the mud, a behavior known as aestivation that is also practiced by some members of the venerable lungfish clan.

But bowfins also have one modern adaptation in their repertoire: They are the only ancient fish that provides parental care to their young.

The male clears a large circle of vegetation to create a nest where the female releases her eggs to be fertilized. Then he aggressively protects the eggs as well as the hatched young until they are several months old. Dad will even leap out of the water, stirring up sediments enough to hide the fry from predators.

Despite its fascinating mix of old and new strategies to survive since the days of the dinosaurs, the bowfin is not admired by anglers because it eats desirable game fish. Fisheries biologists note, however, that bowfins are an important part of the aquatic ecosystem. Their presence is often an indication of good fishing waters because they help to maintain panfish and sport fish populations at healthy levels.

Bowfins themselves will strike hard at bait or a lure and put up as good a fight as a bass if hooked. Even out of the water, bowfins will try to bite with their razor-sharp teeth. All comparisons with a sport fish end there, however, with another survival adaptation: Bowfins hit a sour note on taste.

Jazzin’ at the Shedd is sponsored by Bank of America.

In the ocean, marine life resembles a perfectly tuned jazz band. Each plant and animal species has a unique note to play; together they form an extraordinarily beautiful, complex arrangement. At Shedd, our conservation and research programs work to keep the music playing without missing a note.

Karen Furnweger, web editor

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