Jazzin' Instrumentals: The Drums
You’d be hard pressed to find a bigger percussion section than the drums, or the Sciaenidae family, which includes 275 species of freshwater and marine fishes found in temperate and tropical waters throughout the world.
And we mean percussion literally. The males have special tendons that vibrate against the swim bladder, producing a sound underwater similar to a drum beating in the distance. It is most likely a rhythmic love call to the female of the species. (If you remove a drum from the water, the distressed fish will bellow like a bullfrog, earning it another common name, croaker.)
Freshwater drums—handsome, deep-bodied 20-inch fish that are slate gray with brownish-purple fins—are part of the idyllic community in the “healthy ecosystem” habitat of the Great Lakes Invasive Species exhibit in Shedd’s Local Waters gallery. They are so local, in fact, that you don’t have to look much farther than Lake Michigan to see freshwater drums in the wild.
“They’re really common,” says senior aquarist Kurt Hettiger, “especially if you go to the area harbors.” They are also quite numerous this year, he says. “We don’t know why. It could be that the forage is correct for them. They’ll forage on invertebrates along the bottom. That’s why they have those downturned mouths.” The fish also use their blunt snouts to flip small stones as they search for crayfish, clams, snails and even small fishes (including juvenile drums).
During the spring breeding season, freshwater drums are as musical as the rest of the family—the grunniens in their scientific name, Aplodinotus grunniens, means grunting. “I’ve heard the sound, lots of times,” says Kurt.
These fish are also notable for their large otoliths, the round bones found in fishes’ ears. Measuring up to an inch in diameter, the otoliths have been used as “lucky stones,” currency and, polished to a ivorylike finish, jewelry.
The freshwater drum is an important sport fish in the Mississippi and Missouri Rivers, and while these fish typically weigh between 5 and 15 pounds, the record is 54.5 pounds—which must have seemed like a kettle drum.
This species is the only North American freshwater representative of its family, but it’s widespread, ranging from Canada to the Gulf of Mexico and on down through eastern Mexico to Guatemala.
Moving into salt water, in the Caribbean (and the Caribbean Reef) you’ll find the spotted drum. At first glance, there’s no family resemblance to our native
drum. This is a much smaller fish—6 to 9 inches—with a towering dorsal fin and eye-popping combination of stripes and spots. (Immature spotted drums, like the one pictured here, only have bold ebony-and-white stripes.) But just look at its shape and you’ll see the characteristic deep body, blunt snout and downturned mouth for bottom feeding.
Spotted drums are also found on reefs in the Gulf of Mexico, off Florida and in the Bahamas. This is a secretive and solitary fish, and you might have trouble finding one in the grotto habitat at the back of the Caribbean Reef. During the day spotted drums don’t stray far from the shelter of overhanging or small caves, only venturing out after dark to forage on the seafloor for crabs, shrimps and marine worms.
Be sure to beat it to Shedd to check out the drums and catch Jazzin’, too, Wednesdays from 5 to 10 p.m., through Sept. 5.
Jazzin’ at the Shedd is sponsored by Bank of America.
Karen Furnweger, web editor