Among these small creatures are the single most successful animals that ever lived—the water bears who will be mentioned later. They’ve been on earth for 500 million years, and their phylum has come unscathed through every known extinction period, however drastic. They’ll be here long after the rest of us have gone extinct, and most of us have never heard of them.
Worms are another example. How many of us know about worms? We think we do—we think they’re good for the soil and all that—but as it turns out, such knowledge while accurate is minimal. One of the greatest mysteries in biological science involves the simple earthworms I see on my driveway after a rain. They’re not native to this country. You’ll see what I mean when you read the essay about them.
All in all, if the smallest animals were big, we’d understand them better, we’d be used to their appearance, and we’d admire what they do. These tiny creatures can learn, as has been demonstrated scientifically, and they also have emotions such as fear and even frustration or disappointment, as another essay will explain. I once watched a tiny beetle trying to make a decision, but I was with other people, one of whom brushed it off my sleeve, which it was trying to explore. That ended my observation, or I’d describe it.
Imagine looking at a soaring eagle, high above us in the sky, a noble, magnificent creature. If the eagle were the size of a fly and flew around us, we’d spray it with one of the many lethal chemicals developed for that purpose. These smallest animals will never be big enough for most of us to feel any connection, but the better we know them, the more we can appreciate the paths that evolution has taken to create this enormous complexity of life-forms. Only one of these life-forms is us.
—Liz
Slugs
— Liz —
The names of animals have different connotations. To call someone a pig is fairly insulting, to call someone a louse is highly insulting, and to call someone a slug is exceptionally insulting, implying laziness, stupidity, and uselessness, so I’m wondering how readers will react when I say I’d like to have a slug as a pet. “You want a slug?” someone will cry. “What for?”
Let me explain. After a brief, much-needed rain, I was behind our house checking the rain gauge (we got almost an inch that time) and what did I see but five slugs in the still-damp grass! Two of them were mating—one was on top of another one, anyway—a third slug was at a slight distance, perhaps also thinking of mating, and a fourth and fifth were a few feet away, both minding their own business and evidently relaxed as if they had already mated. Years had passed since I’d seen a slug or even thought about them, so I was excited.
Our planet has many kinds of slugs, which are related to snails, clams, oysters, and octopuses. I don’t know which kind mine were except that they’re known as gastropod mollusks, which means “stomach-foot mollusks,” because like snails they slide along by contracting the skin on their bellies from the waist down while stretching the skin from the waist up, then doing the opposite. Somehow they flow forward smoothly and surprisingly quickly, considering that their featureless bodies look the same from all directions and seem even less complicated, say, than a banana. Their bodies are versatile, however. Like an octopus, a slug can push its body through the tiniest hole, a little at a time. And when they move they squeeze out a small amount of slime, which helps them glide quickly and also protects their undersides from roughness.
But often enough when you look at a slug, you see nothing more than a tiny brownish oval shape that isn’t moving. So what surprised me when I saw the slugs in question was their awareness, especially from the two slugs mating, as if the slug on top felt the need to understand his surroundings. Slugs are hermaphrodites, having both male and female organs, but the slug on top seemed to be taking the male role. His rear end (I use his because of the role he was playing) seemed to be adorned with tiny, dark protuberances not evident on the slugs that weren’t mating, and was partly wrapped around the slug below. He seemed to feel responsible for the safety of them both because he appeared to sense my proximity. Up from his pale brown front end came one of his eyes. Nothing happened for a while, so I moved a little closer, and up came the other eye.
A photo of a slug usually shows her (I don’t like to call an animal “it”) with what looks like a V shape of two tiny horns made of the same material as the rest of her body. These come up from her front end and carry her eyes. At the tip of each horn is an eyespot. Not all slug species have these eyespots, but these slugs did, complete with lenses with which they see objects as we do but not in color. If a slug doesn’t feel the need to look at something, she pulls her eyes back down into her body, where they disappear without a trace.
If eyes suggest a forehead, then two other sense organs come out of her chin—two much smaller horns that inform her of taste and scent. The sense of touch is in her entire body. She has no sense of sound but perhaps can feel vibrations. The slug I watched didn’t put out his taste and scent organs, perhaps because he wasn’t overly concerned. He even withdrew one of his eyes and left only the other to keep track of me.
We tend to see the slug types as disgusting. Surely they’re damaging our flower beds or doing something else that’s awful so we stamp on them or even put out poisons. But any life-form is fascinating if you watch it long enough, and the small, slow-moving animals are particularly favorable because you can watch any one of them indefinitely and note all kinds of behaviors. Just think what you could learn by watching slugs—not when you’re high above them on a rain-dampened lawn, but at eye level beside a glass aquarium planted with moss and other vegetation, complete with their favorite foods and easy access to water. I’d learn from them and find out if they’d learn from me. If a single-cell organism can learn and remember things, as has been demonstrated with paramecia, and if birds and fish can recognize individual humans (most humans can’t recognize individual birds or fish), who knows what a slug can achieve?
A marvelous book, mentioned earlier in another essay, was written on this subject, The Sound of a Wild Snail Eating by Elisabeth Tova Bailey. It’s about a snail while this essay is about a slug, but they’re the same thing, really—a snail is a slug with a shell. I can’t get enough of this book—it opens a world of utterly fabulous creatures that most of us know nothing about. After you read it, you will never again see a snail or a slug without marveling. You might even want one as a pet.
Worms: Lowly and Exalted
— Sy —
Found only in a critically endangered ecosystem known as the Palouse prairie, a storied giant was long thought to be extinct. Only a handful of sightings have been reported since the 1970s. Today there are only ten of these animals in captivity in the world. Seeing a rare species is one of the highlights of a naturalist’s life—and on one day in Moscow, Idaho, I was thrilled to have the opportunity to see one.
In the second-floor laboratory at the University of Idaho’s College of Agricultural and Life Sciences, PhD candidate Chris Baugher did the honors. From a plastic Tupperware container the size of a shoe box, and onto some moistened white filter paper, he dumped out several cups of black dirt. And there it was: a worm.
Not just any worm, mind you. This was a giant Palouse earthworm—portrayed in the media as a “spineless, subterranean Bigfoot,” described as “Moby Worm,” and considered by worm experts to be the holy grail of North American earthworms. I had read it was white, grew to grow more than a yard long, and spat saliva that smelled like lilies.
The worm before us was none of the above. It wasn’t white at all—mostly reddish purple with a handsome, peach-colored forward section. It was only about eight inches long. And Baugher and soil scientist Jodi Johnson-Maynard, considered the world’s top experts on the animal, admit they’ve never been able to detect its scent.
To my untrained eye it looked a lot like the common night crawlers they sell at the Hancock Market here in New Hampshire to bait anglers’ hooks.
But n
ight crawlers—the reddish gray species you find on sidewalks after a rain—are, like most earthworms now found in the United States, an invasive species. They arrived in ballast used to steady early ships from Europe. “Of the six thousand species of earthworms,” explained Baugher, “very few are native. It may be that the giant Palouse earthworm has been here for a very long time.”
Shockingly little is known about any of our native earthworms. There is only one working earthworm taxonomist in America. International earthworm experts gather at a symposium only once every four years. The giant Palouse earthworm illustrates just how mysterious are the lives of the little creatures who live under our feet—animals to whom we give little thought.
But Johnson-Maynard reminds us that earthworms have profound effects on our lives. “To many people the soil is just a black box we walk on,” she says. But it’s the foundation of our food chain and, she points out, importantly regulates gas exchange with the atmosphere. Soil sequesters three times as much carbon as the atmosphere, adds Baugher. And earthworms are soil’s stewards.
It’s difficult to learn about animals who live underground. Baugher and Johnson-Maynard have made plaster casts of their burrows. They have tried digging the worms up, but that’s a good way to cut them in half—not a good thing to do to a rare species. Genetic expert Lisette Waits is working on ways to identify their worms’ burrows by DNA gathered from swabbing mucus (which they secrete to speed their passage) from burrow walls.
“To cultivate the giant Palouse earthworm is a real chore,” said Johnson-Maynard. Nobody is sure what type of soil it prefers, how wet to keep it, or even what it eats. Night crawlers come to the surface at night and carry leaf litter down to their burrows to feed. Maybe the giant Palouse does the same; maybe not. “We’re just trying to keep them alive.” (That’s why the worm I saw was dumped out of its container; the researchers need to make sure their animals are still alive.)
Most of the specimens in captivity were brought in by one man, Cass Davis. He’s a self-described “liberal redneck,” an Earth First! environmentalist who feeds himself by hunting and fishing. “I’m quite familiar with worms,” he told me. “I’ve put a lot of worms on hooks.” He used to swallow night crawlers on a dare; that way he earned chewing tobacco as a teen. Now fifty-two, he found his first giant Palouse earthworm in 2012 in a rut on a road. It had been run over, but even in this condition, it didn’t look like a night crawler. He brought it in to the university lab—and sure enough, it was the storied worm. He has a photo of it—and all the others he’s found—on his cell phone. “They have beautiful lips!” he told me as he displayed the picture.
Davis is one many citizens of this corner of Idaho, including a number of farmers who have collaborated with the university scientists, who are proud to share the home of the giant Palouse earthworm. (Though some farmers—ironically the very recipients of the worms’ hard work aerating the soil!—fear that if conservationists get the worm endangered status, it could restrict use of their land.) “Citizen scientists have been very important to the project,” says Johnson-Maynard. Folks bring animals into the lab all the time, hoping they’ve found the elusive worm. One person brought them a very small snake; another brought in a leech; and once someone brought a photo of a long white thing that turned out to be the intestine of a large mammal.
Still, Baugher and Johnson-Maynard are grateful to them all. They love it that the giant Palouse gets people excited about earthworms. “It’s unique to this region. It draws them in,” says Johnson-Maynard. “And it really is a beautiful animal!”
Amphibians
— Liz —
The only amphibians we now know are the salamander and frog types (toads are frogs), and we think of them as nothing much, not realizing that tiny though they are, their brains are fully functional, with consciousness, memory, thoughts, and even emotions. In short, their brains are more or less like ours except specialized for different problems and focused in different directions. It’s true that an amphibian has yet to write a book or design a nuclear reactor, but we humans have yet to successfully spend our childhoods as fish before morphing into land-based life-forms in an entirely different ecosystem with all-new problems we must then solve. That amphibians do this perfectly we see as nothing. That’s just us, though, with the normal human reaction to a nonhuman life-form.
Amphibians are faced with extinction. Believe it or not, this is due in part to a certain fungus that during its infancy swims like a fish. You read that right—the spores of certain fungi swim like fish. They also swim with a goal in mind, and the goal is an amphibian to whom they can attach, just as a coral polyp attaches to a rock. While swimming around, these fungi find their victims by sensing the proteins and sugars in their skins and swim toward them, then attach to them, grow their hyphae (their “roots,” so to speak) down through the victim’s skin, then suck the juices from the victim, who eventually dies of heart failure. I’d say this fungus has some powerful abilities, and those who do this are known as chytrids, which, for reasons yet undetermined (but probably through human activity), are spreading worldwide; hence all amphibians are threatened.
If amphibians go extinct, which could certainly happen, an entire taxonomic class would disappear. That’s all the animals of a certain group, when normally it’s just a species that goes extinct. Losing an entire class would be as bad as losing all the birds or all the mammals and worse than losing all the dinosaurs, because certain dinosaurs turned into birds and in a sense are with us now.
But despite the horror that’s waiting to happen, we still don’t help amphibians. We are among their most important predators, and we kill them on damp nights in the spring when they’re crossing the roads. Amphibians must do this for several reasons—sometimes to find mates, sometimes to forage, and sometimes to travel to the vernal pools in the woods that form when snow melts. Because these pools are not connected to streams or ponds, fish have no way to reach them, so many amphibians lay their eggs in these pools, knowing that their eggs will not be eaten and most will survive and hatch.
Amphibians travel at night because the air has more moisture. The modern amphibians have some kind of lungs, but they also take air in through their skins, which must be damp for this to happen. Thus they must move when the air is damp and won’t dry them too badly. But most are so small, relatively speaking, that no matter how quickly they move, they can’t cross a road in a timely manner, which puts them at great risk. A car is to them what a bomb would be to one of us.
If not for them and their brave journey with the hardships they endured when leaving the water for the land, we would still be fish, not people with cars to squash them. Thus we owe them the courtesy of not running over them. So please, everyone who reads this, know that a careless or uncaring driver can kill as many as twenty amphibians all at once. Not even the little dinosaurs who turned into birds had to withstand that kind of predation.
Here in New Hampshire where I live, groups of volunteers go to the most dangerous roadsides—those that amphibians have been known to favor—to assist the little frogs and others who are trying to cross. The volunteers wave at the cars to ask them to slow down, and many do. Sometimes the volunteers have signs that say “Save the frogs.” Sometimes the drivers wave at the volunteers to thank them. And the frogs that were hopping across the road finish their journey, hopefully to live, find a mate, and make more little frogs.
Bumble, Bee Happy, Bee Smart, Bee Safe!
— Sy —
Like many kids, I used to lie in the grass and watch bumblebees harvesting pollen from the clover. Unlike many other bees, these big, furry bees were so gentle I could let them crawl across my palm without fear of getting stung. I loved to select one bumble to follow around the yard as she buzzed from clover to rose, rose to snapdragon, sipping nectar from her pointy black tongue and collecting pollen on her fuzzy black-and-yellow coat, later to groom it off to carry home in “pollen baskets
” on her rear legs. Though our parents may have chuckled benignly at our beliefs, I’m sure lots of kids, like me, reported that our insect friends were cheerful and smart.
As it turns out, we were right.
Two separate studies published just a few weeks apart report that bumblebees show emotions, solve problems, and will teach others to how to solve problems, too.
“Even insects express anger, terror, jealousy, and love,” Charles Darwin wrote in The Expression of the Emotions in Man and Animals. But in the ensuing 150 years, his views on emotion fell so out of favor that few scientists even tried to look for thinking or feeling in tiny, invertebrate animals—until now.
It’s difficult to study something as private as an emotion in a creature as different from us as a bumblebee. Unlike our dogs and cats, they have little reason to communicate with us. So neuroethologist Clint Perry at Queen Mary University of London came up with an ingenious experiment, published in the journal Science. His research team trained twenty-four bees to enter a plastic tunnel when a treat was promised. When marked with a blue card, the end of the tunnel offered tasty sugar water. A green sign meant none.
But what about an aquamarine sign? Like you or I might be, the bumbles were confused. Was it green or was it blue? They wandered around, not knowing what to do. Then the researchers gave half the bees a dose of cheer: a surprise treat of a drop of sugar water. Like people in a good mood, they then became more optimistic: They entered the ambiguous tunnel, encouraged to hope for the best. Those who had no sugar water spent just as much energy dithering around but didn’t take a chance that the tunnel would be a good bet. This suggests that the metabolic effects of the sugar weren’t responsible for the bees’ behavior—but the boost in mood was. Who doesn’t cheer up after a sweet treat?
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