Gray Matters: The Minnesota Zoo's Dolphin Problem

Everyone loves the dolphins at the Minnesota Zoo. When one of them dies unexpectedly, especially a young pup, it raises uncomfortable questions about both the dolphins and those of us who love them.

Dolphin at Minnesota Zoo
Cameron Wittig


The dolphin brain is one of the largest animal brains in terms of size relative to body mass.  According to Emory University dolphin and whale neurologist Lori Marino, cetacean (dolphin and whale) brains started expanding 35 million years ago, reaching present-day size 15 million years ago, while human brains started expanding rapidly, overtaking all other animals, only in the last million years. “Dolphins have had their big brains a lot longer than we have,” she says.

Kevin Willis, biological director at the Minnesota Zoo, argues that size isn’t everything and points out that glial cells insulate their brains. “The dolphin’s brain has to function in cold water,” he says. “So the bulk of the total size is for insulation—the size of their brains isn’t just for brightness.”

But that view of glial cells is changing. “We now know that glial cells modify neural transmission, therefore playing an integral role in brain processes not just as ‘supporting actors’ but as real players,” Willis notes.

Although the dolphin brain is organized differently than the human brain, there are similarities: We both have cortexes, for instance. Marino says the recent discovery of “spindle cells” in dolphin brains—long, spindly structures involved in self-awareness, social cognition, and communication, the same mysterious structures found in human brains—is yet more evidence that the two species might be more like-minded than we ever thought. —S. M.

These dolphins live in what is, at one million gallons, a mid-sized dolphinarium relative to facilities around the world. I ask Ehmke what he would do if he had an unlimited budget—far beyond the $8 million the zoo requested this year from the state to repair its pool liner (the zoo received $4 million)—to change the dolphin exhibit. He brainstorms effortlessly. “A lagoon the size of our central lake,” he muses. “Wouldn’t that be marvelous to do? With rocky substrate bottoms, and seaweed, and the whole picture of a coastal environment.”

Then he snaps back to reality. “Again, there are limitations on what’s possible financially. And [Discovery Bay opened in 1997] when the zoo needed to do a new home for the dolphins. That was the primary [consideration], as opposed to the message that some of our other exhibits have.”

Behind a lawyer’s pursed lips he makes an admission. “In my ideal world, every exhibit at the zoo would have the kind of immersion quality that I talked about, and that connection to the environment. I think the most important message that we need to be giving is that these animals need this environment to survive. It’s not as long as we’re taking care of them there’s always going to be bears and there’s always going to be dolphins. It’s more, unless you have an ocean or a forest that’s clean and safe these animals won’t be here in the future. Ideally, I would like every exhibit at our zoo to have that message implicit to it. Right now, honestly, Discovery Bay doesn’t.”

Ehmke goes on to point out that his concern is purely aesthetic. “It’s not from any concern about animal welfare or animal management,” he says. “Neither is that meant to say a lot of education and empathy and other things aren’t instilled by that exhibit, but [the education and empathy is] much more about the dolphins themselves and their charismatic nature rather than a connection between the habitat and the animals.”


This isn’t a murder mystery. Even if there is dolphin-on-dolphin crime in this story, it’s not really a whodunit: The zoo has complied with every USDA requirement for investigation into cause. And these are animals, not people—in the definition of the legal system, in fact, they’re property. But even while we define the terms, and despite the fact that they’re under our care and all it entails—birth control, surgery and medication, the diversions of cuisine and structured play—the laws of nature are still on display: These animals have sex with each other and kill each other, sometimes for what seems to be simple pleasure. The animals in a zoo are living their lives on display for our pleasure, and as our scientific understanding of these same animals becomes more sophisticated, Willis’s question—“Are we responsibly caring for these animals?”—becomes more difficult to answer. It just might be impossible to answer.

Senior writer Steve Marsh’s work also can be found in Delta Air Lines’ Sky and at GQ.com and nymag.com.