Gather ’round and listen to my tale of Shedd Aquarium’s most mysterious animal, the invisible hellbender.

What’s a hellbender, you say? Why, it’s a phantom amphibian, a salamander up to 2 feet long, wrinkled, slimy and beady-eyed, given to making its home under rocks in clear, fast-flowing streams. And while it has lungs, it never has to come up for air. Legend has it hellbenders cavort with trolls and troglodytes on moonless nights.

And nigh on 12 months ago, right around Halloween, one arrived unbidden at Shedd Aquarium’s door. For two months, it was in plain view in quarantine, as solidly real as a soft-bodied amphibian can be. Then, with barely a ripple, it slipped into a Local Waters habitat, amidst darters and dace, stonecats and madtoms. And it hasn’t been seen since.

So where the heck is the hellbender?

“Believe me,” says senior aquarist Kurt Hettiger, “I spend a lot of time looking for it.”

Kurt, whose knowledge of local aquatic life runs as deep as an underground river, knows the animal is in there. “And I knew that this was going to happen. I just hoped it would come out once in awhile.”

The “problem” is that the darter exhibit happens to be ideal hellbender habitat: cool and shadowy, with a nice midstream current—and lots of underwater nooks and crevices, and even a hidden mud hole amid the ferns and other vegetation in the land area, in which to conceal itself. And rocks, lots of rocks, which hellbenders love to burrow under. In other words, the hellbender immediately made itself at home and isn’t venturing out of its cozy hideaway for any frivolous reason such as an aquarist looking for it.

Hellbenders, Cryptobranchus alleganiensis, are North America’s largest salamanders. As their species name reflects, their native range runs a rocky diagonal from southern New York to northern Georgia, branching a little into southern Indiana and Illinois. While they are not on the federal endangered species list, they are protected in several states, including Illinois, where they are endangered. In the few remote places where hellbenders are still common, they are indicators of excellent water quality.

Despite having functioning lungs, and often gill slits left over from their larval stage, the totally aquatic hellbenders absorb oxygen from water through capillaries in the deeply folded skin on their sides. Their specific environmental requirements of constant levels of dissolved oxygen, cool temperatures and swift water flow mean that they are vulnerable to siltation from agricultural and residential runoff, the damming of rivers and chemical pollutants, especially some toxins found in herbicides, which disrupt their hormones and cause reproductive failure. Add to the environmental degradations that have put hellbender populations in a tailspin overcollecting for the pet trade.

In fact, Shedd’s elusive hellbender was part of a large shipment of amphibians and reptiles passing through O’Hare. While it is not illegal to export hellbenders, an exporter must provide documentation for each animal’s origins, including a collecting permit if it came from the wild. The hellbender lacked the proper paperwork, so U.S. Fish and Wildlife Service inspectors confiscated the animal and brought it to Shedd.  

Shedd works closely with the U.S. Fish and Wildlife Service to help identify aquatic species in suspect shipments and to provide a safe haven with expert care to seized animals. Confiscated animals often become part of Shedd’s permanent collection. So it was with the hellbender.

Aside from being thin when it arrived, the animal checked out as healthy. He was plumped up during quarantine on silversides and earthworms and bits of shrimp and clam. And Kurt continues to toss in those tempting tidbits as he feeds the fishes in the habitat. “I’m surprised I haven’t seen it after I get done feeding.”

He continues, “Hellbenders are pretty much nocturnal, so it might come out at night and rummage around.”

The next step might be to stake out the darter exhibit late at night and, equipped with night goggles, wait for a subtle, shadowy movement—from the back of the habitat? from under a rock?—to finally give away the mysterious hellbender. Maybe the aquarist has some trolls and troglodytes that he doesn’t know about, too.

Or maybe Kurt will just keep looking during the day as he tends the fishes and maintains the habitat. He has time—hellbenders can live close to 30 years. “I’m sure it’s happy in there. It has everything it needs.”

Posted by Karen Furnweger, web editor  

Editor’s note: The hellbender is invisible no more! This impressive amphibian is in full view in its own focus habitat in the At Home on the Great Lakes exhibit.