Great Adaptations
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Great Adaptations

Star-Nosed Moles, Electric Eels, and Other Tales of Evolution's Mysteries Solved

Kenneth Catania

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eBook - ePub

Great Adaptations

Star-Nosed Moles, Electric Eels, and Other Tales of Evolution's Mysteries Solved

Kenneth Catania

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About This Book

"The irresistible enthusiasm of Great Adaptations couldn't come at a better time."—David P. Barash, Wall Street Journal "Be very amazed."—Carl Safina, author of Beyond Words and Becoming Wild How one scientist unlocked the secrets behind some of nature's most astounding animals From star-nosed moles that have super-sensing snouts to electric eels that paralyze their prey, animals possess unique and extraordinary abilities. In Great Adaptations, Kenneth Catania presents an entertaining and engaging look at some of nature's most remarkable creatures. Telling the story of his biological detective work, Catania sheds light on the mysteries behind the behaviors of tentacled snakes, tiny shrews, zombie-making wasps, and more. He shows not only how studying these animals can provide deep insights into how life evolved, but also how scientific discovery can be filled with adventure and fun.Beginning with the star-nosed mole, Catania reveals what the creature's nasal star is actually for, and what this tells us about how brains work. He explores how the deceptive hunting strategy of tentacled snakes leads prey straight to their mouths, how eels use electricity to control other animals, and why emerald jewel wasps make zombies out of cockroaches. He also solves the enigma of worm grunting—a traditional technique in which earthworms are enticed out of the ground—by teaming up with professional worm grunters. Catania demonstrates the merits of approaching science with an open mind, considers the role played by citizen scientists, and illustrates that most animals have incredible, hidden abilities that defy our imagination.Examining some strange and spectacular creatures, Great Adaptations offers a wondrous journey into nature's grand designs.

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Information

Year
2020
ISBN
9780691209555

1

THE ENIGMA OF THE STAR

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“It is a riddle, wrapped in a mystery, inside an enigma.” These are the famous words Winston Churchill used to describe the inscrutable inner workings of the Russian government in 1939. But he might as well have been talking about the star-nosed mole. It’s one of the most unusual creatures that has ever walked—or more accurately, burrowed through—the Earth. Everything about it seems strange. It’s a mole, but it likes to swim; it has a high metabolism but thrives in the coldest parts of North America (without hibernating); it makes its living digging through mud, but its lustrous fur is spotless; it gets eaten by owls and weasels and other predators, but it only needs to breed once a year to maintain large populations. It has strange teeth and clawed shovels for hands. But the real mystery, the thing that makes you stare, is that nose. If one day you are lucky enough to cross paths with a star-nosed mole, don’t feel self-conscious, everybody stares, and the mole can’t see, so no harm done.
I am inordinately fond of these animals, which have played a big role in my life as a scientist. As I look back, I’m surprised by how often chance encounters and luck seem to have carried me past hurdles. I’m going to recount some of these adventures, along with many discoveries about animal behavior, evolution, and neuroscience. In science, we are taught to recognize generalities in the strangest specifics, and this is epitomized by studies of the star-nosed mole. Although the mole is essentially blind, it has provided new insights about visual systems and the organization of mammal brains. And while its star-shaped nose seems entirely unique, this structure is a case study in the relationship between development and evolution—and demonstrates that missing evolutionary links can sometimes be found . . . right under your nose. Studying this astonishing animal has taught me many things; most importantly it has taught me how to be a scientist. There’s no doubt the mole’s star also gave me a taste for biological mysteries.
For starters, though, you might wonder why anyone should care about a strange little mole with a weird face. Perhaps an analogy will serve. If you were a mathematician, you would know all about the legendary unsolved math problems. The most famous are the seven so-called Millennium Prize Problems. If you were the first to solve one of these, you’d get a million dollar prize, not to mention the prestige that goes with solving such a long-standing question. The situation is different in biology because it’s not always clear what any given problem might be, and there’s seldom only one answer. And yet the star-nosed mole has stood out as an unsolved biological “problem” since it was first described in the 1800s. It is the living, breathing embodiment of a question—actually many questions. What is the star? Is it an extra hand or some kind of sensor, or both? Is it used for digging, for smelling, or as part of a bizarre mating ritual? Why doesn’t any other mammal have a star? How did it evolve? How does it develop? What ability might it give the mole, if any? Many biologists have asked these questions over the years, and you don’t need a background in calculus and differential equations to find the answers. But you do need a star-nosed mole, and these are not easy to find.

THIRD TIME’S THE CHARM

So how did I get involved with star-nosed moles? As with much in life, early experiences were key. As far back as I can remember, my parents encouraged my obsession with animals of all kinds. A couple of incidents stand in for a thousand other stories. When my pet water snake escaped, I searched everywhere but couldn’t find it until days later, when we realized it was visiting my father’s aquarium and eating his fancy guppies. Not long after that, my four-foot-long black rat snake escaped and joined my mother for her afternoon nap—no doubt innocently searching for warmth. My parents were unperturbed. They suggested I return the snakes to their cages, the same way they might remind me to put the milk back in the refrigerator. I was very lucky.
My parents also accidently introduced me and my brother to star-nosed moles through a book called Animal Oddities. We took great pleasure making fun of the strange animal faces, especially the proboscis monkey and the hammerhead bat. But we didn’t make fun of the star-nosed mole; it was simply too weird. I still remember the artist’s drawing of all those creepy appendages ringing the nose.
That early memory came in handy the second time a star-nosed mole entered my life. I was engaged in an intensive program of study that would form the foundation of my professional career, though I was only ten years old and my classroom was the forests, streams, and lakes of Columbia, Maryland. I was always searching for creatures, having by then graduated from insects to snakes and turtles, while also pursuing minor studies in quartz crystals. It was the crystals I was after that day as I walked along the stream bank and jumped onto each small beach of sand and rocks, hoping to see the glint from a facet. Instead, I found a small, dead body practically on display in the middle of a jumble of broken quartz. It was that oddest of oddities—a star-nosed mole, fleshy appendages and all. I was dumbstruck. Finding a dead animal didn’t disturb me—that was common enough in the forest. But the meaning was clear: a creature that had earned a place of honor alongside exotic monkeys, strange bats, and giant anteaters lived practically in my own back yard.
I told my mother about my miracle discovery, and we got out her field guide to mammals. The first thing I checked was the mole’s geographical range, not that there’s much to confuse with a star-nosed mole. But I was always secretly hoping for a momentous discovery—imagine the news if star-nosed moles were supposed to live in the Amazon rainforest. The range map showed them restricted to eastern North America, all the way from the Smoky Mountains of Tennessee to what seems to be their favorite place, way up in eastern Canada. The entire state of Maryland was included, so no need to call the newspapers. I was surprised to learn this mouse-like animal isn’t a rodent; moles and shrews are instead part of a different order of mammals, the so-called insectivores that eat insects and other invertebrates. I also learned that star-nosed moles are common in wetlands and are semiaquatic, meaning they spend part of their time swimming and diving for food in streams and ponds. So that’s why it was in the middle of the stream; the mole hadn’t fallen into the water and drowned as I had imagined. It lived (and apparently died) around water. I added this new creature to my watch list and from then on I was always on the lookout, especially when exploring the upstream wetlands. I never did find another star-nosed mole in Columbia.
The third time star-nosed moles entered my life, I was an undergraduate at the University of Maryland majoring in zoology. This was the obvious path for me, but there was a problem. There weren’t many courses that included animal diversity or behavior, and there were few options to work directly with animals. I was bored. Concentrating on something you find boring is like being on a diet; it’s almost impossible to stick to it.
Added to that, I was distracted by a part-time job that was, if anything, too exciting. I was riding (and falling off) horses at Renaissance festivals for $150 a weekend (that was good money for two days’ work in the 1980s). It was fun, at first. But there were frequent injuries, and I had come to realize I didn’t have the “right stuff” for such a dangerous job. What I really wanted was something exciting to do in biology—some form of real research.
It was around this time that my father met Dr. Edwin Gould, the head curator of mammals at the National Zoo in Washington, DC. It wasn’t a chance encounter. My father is a psychology professor specializing in learning (he earned his doctorate working with the psychologist B. F. Skinner), and one day both he and Dr. Gould attended an informal gathering of local researchers interested in animal behavior. Dr. Gould was looking for a volunteer to help care for animals and, if the right person came along, to help conduct research at the zoo. The job would be focused on just one animal— the star-nosed mole.

LIONS AND TIGERS AND MOLES

I imagine that a law student interviewing for an internship would be awed by a firm’s towering headquarters, with partner names spelled out above the entrance. In my case, the architecture couldn’t have been more different. But to an aspiring biologist, going for an interview in the zoo’s hidden offices below the lion and tiger exhibit felt pretty momentous. I was met at the front desk and led around the circular hallway to a room that was mostly underground, with upper windows facing into the exhibit. Dr. Gould introduced himself and invited me to sit on a couch opposite his desk. I couldn’t help but notice the windows that normally viewed the cats were blocked with what seemed to be a haphazard arrangement of dark cardboard. He saw my look and told me, “It’s hard to concentrate on work when you can look into the exhibit instead.”
Maybe that’s all there was to it. But not long after my meeting I learned that a Siberian tiger had recently smashed through a window at the Houston Zoo, pulled a keeper through the opening, and killed him.1 The keeper had arrived early and was alone, so no one saw it happen. Presumably, the tiger got excited by the movement at the window and attacked.
Dr. Gould never mentioned it. Instead our discussion centered on smaller mammals that don’t try to eat anyone. These were kept (appropriately) in the Small Mammal House. He was proud that the National Zoo was the only place in the world with star-nosed moles in the collection. The problem was, they only live a few years and won’t breed in captivity, so they often needed to be replaced—not just for the exhibit but also for research.
“I can catch them,” he said, “but I don’t have time. I’ve got a guy—Bill McShea—he’s been collecting in Pennsylvania and bringing them to the zoo, but he’s too busy now. The thing is, the moles are really hard to find. You have to know how to identify their habitat and then find their tunnels.”
When I told him about my chance finding of a dead star-nosed mole years earlier, his eyes lit up. He also lived in Columbia and knew the area well. We compared our “field notes.” My field notes were the memories of a ten-year-old, but I knew exactly where I had found the mole’s body and what the habitat was like, and I had searched the upstream wetland and found spotted turtles. (I didn’t know it at the time, but spotted turtles and star-nosed moles are often found in the same parts of Maryland.)
This is probably what got me the job. I might not have found the moles, but I had definitely tried harder and gotten a lot closer than the average ten-year-old. Presumably, with a little training, I could learn how to actually catch them (although sadly not in or near Columbia, as the wetlands I knew so well had been turned into housing developments). The best place to find them nearby was in northern Pennsylvania. If I could go and collect the moles, care for them, and run experiments, it would kill three birds with one stone, so to speak.
It wasn’t just the field work that sounded exciting to me—there was also the research project, which seemed like something out of science fiction. As a mammal specialist, Dr. Gould had often wondered about that enigmatic star, and he had an idea. What if the star was a radar dish of sorts, used for detecting electric fields? At first this seemed pretty far out. Then he told me about a sense called “electroreception,” and I began to realize there was a whole realm of animal senses that I knew nothing about.
Sharks are the best-known example of an animal with this sense.2 They can detect an electric field of only 0.00000001 volts per centimeter. That’s about 6 million times smaller than the field generated by a double A battery if you dropped it in a glass of water, and we humans can’t even sense a double A battery when we hold it in our hands. What use is this sense to a shark? Your first guess would probably be right—the better to find you and eat you. Picture any typical movie scene with a patient in a hospital bed (perhaps recovering from a shark attack). There’s always a beeping heart monitor in the background. The beep is the amplification of electric pulses that pass from the heart to electrodes on the chest, and from there to an amplifier and speaker. That’s just one of many of electrical noises made by animals.
There are many other fish that have this sense, but the big splash at the time was the discovery that the duck-billed platypus uses electroreception.3 Hennick Scheich and his colleagues first showed that the platypus can find objects using electric fields, much like a shark. Next they recorded signals from cells in the platypus brain to demonstrate where information about electric fields is processed. The results were extraordinary—basically illustrating a “sixth sense” in a mammal—and it got them the cover of one of the most prestigious journals in science, the journal Nature (where Watson and Crick published the structure of DNA.) The discovery was in the news, and Dr. Gould heard the story on the radio as he was driving and pondering star-nosed moles. What if that was the answer to the long-standing “star enigma”? It was an audacious idea, but it seemed to make sense.
Everything about the job sounded exciting, and my enthusiasm must have been obvious. I would be working for free, but that was fine with me. I accepted the job as the new “mole man” at the National Zoo. There was only one hitch; everything depended on finding more moles. How hard could that be?

THE SNIPE HUNT

Imagine you have moles in your yard (maybe you don’t have to imagine). What if I asked you to catch one? It can be done, but it’s not easy. Moles can detect your softest footsteps, and they are especially alert for sounds of digging. They know every inch of their tunnels like the back of their giant, clawed forepaws, and they avoid areas that have been disturbed. They have escape routes from their main tunnels and escape routes from their escape routes. When cornered, they dig a short tunnel and then backfill the entrance, magically disappearing as if through a secret door, and you’ll never guess they’re sitting just a few inches away. Plus, they have special hemoglobin in their blood, allowing them to survive in that secret hideaway with little oxygen and high levels of carbon dioxide, until a predator (or a biologist) loses patience. It’s hard to catch one, even when the tunnels are clearly outlined on a manicured lawn.
But star-nosed moles don’t live in suburban neighborhoods. They live in the moist and muddy soil of wetlands, swamps, and bogs, and their tunnels can be nearly anywhere in a complex overgrown wilderness. They live throughout much of the northeastern United States and are not threatened or endangered, but they are mighty hard to find. That’s partly because you can’t see their tunnels. But also because many other small mammals live in wetlands, so even if you locate a tunnel, there’s no knowing who made it or who’s using it.
I had only a vague understanding of all this when I set out for Pennsylvania in a rented cargo van with a sleeping bag and a cooler full of hundreds of earthworms to feed hungry moles. It was a time in my life when sleep seemed overrated, and I could live for weeks on atrocious junk food. I brought a few bags of groceries, a pair of rubber boots, and a bundle of older clothes that I didn’t mind destroying. I splurged on flashlights—one light bulb didn’t seem sufficient for wandering around the foggy forest in the middle of the night. The plan was simple—meet Bill McShea in rural Pennsylvania and learn how to trap star-nosed moles.
The rendezvous was a beautiful piece of land with lush grasses, a small stream, and a forested foothill in the background. I got out of the van as McShea approached, and I could already picture us walking together up the hill and following babbling brooks into the sunshine as he pointed out the details of the mole’s habitat. This was surely going to be easier than I thought.
After brief introductions, he told me to follow him, but he went the wrong way. Instead of taking my imagined path up the sun-dappled hillside, we trekked downhill toward the muck and tussocks of a low-lying swampy area not far from the access road. It didn’t take me long to realize that catching star-nosed moles did not include hopping from stone to stone along clear mountain streams like a wood elf. It was more the job of Gollum, kneeling in the muck of the lowlands, head down, digging with bare hands alongside the grubs and earthworms. I was surprised but not disappointed. I didn’t care where I had to look—I was on a mission for the National Zoo.
I hung on McShea’s every word, but my trapping lesson was surprisingly short. He showed me what a mole tunnel usually looks like, where they tend to dig, how to set and check a Sherman trap (a small, metal box with a spring-loaded door), how often to check traps (every three to four hours, day and night), and how to clean traps (throw them into the stream). He said that each of the hundred or so traps was quite expensive. It all seemed doable, since he had already scoped out the area, found tunnels, and had caught star-nosed moles there before. Then came the shocker. The land belonged to his in-laws, and they didn’t want anyone else on the property. I would need to take the traps and find another place. How was I going to find another place? Thirty minutes after my lesson began, I was turned loose with my Pennsylvania map, my van full of supplies, and the traps.
People often reminisce about forks in life’s road, though it’s usually a metaphor. There was nothing metaphorical about my predicament. Which of the many roads would lead me to this legendary creature? It’s not as if a cure for cancer lay in the balance, and yet I had somehow landed at the nexus of an exciting research project at a very early stage in my (hoped for) career. Everything depended on my next choices.
I won’t try t...

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