TWO
Planet Predator
No one seems to approve of predation but, like sin, it is not often that anyone succeeds in stopping it for an appreciable length of time.
—Durward Allen
Genesis: The First Bite
Not long after a swirling cloud of cosmic dust and gas condensed to become the solar system, life arose on the third planet from the sun. Earth in those times, some four billion years ago, was an alien realm of rock and water under violent assault, showered in lava, shocked by lightning and bombarded by ultraviolet rays beating unhindered through an atmosphere starved of oxygen. Simple organic molecules, synthesized with the flashing of heat, spiced the oceans, eventually bonding to produce a protein-coated cell encircling a spiraling, replicating strand of nucleotides nicknamed DNA. For a billion or more years, life was just such a simple, single-celled affair, of bacterial microbes feeding off the sun, reproducing without sex. Then one day, as the theory goes, one of those cells somehow swallowed its neighbor. And life, as they say, would never again be the same.
It was a natural step or two beyond that for predator and prey to add spermlike tails and fluttering cilia of rudimentary self-propulsion, the first glimpses of the chase. With this new race of supercells now roaming the seas, evading and pursuing and eating each other, size too became an issue. For the sake of survival, it was a good idea to be bigger than your attacker could swallow. Two ways of doing that were either to grow a bigger cell or to join with other cells into a more forbidding collective mass. An answer to increasingly dangerous times was under development, in the form of multicelled organisms.
By introducing “hazard to complacency”—in the words of paleontologist Stephan Bengston—predation had begun transforming a generic world community of microbes to a biosphere humming with complexity and gigantic potential. For a long time that potential lay smoldering among the miniature masses, until one more defining moment in the history of life, when life itself erupted.
The Big Bang
Marine fossils paint an idyllic scene of animal life in its infancy, off the naked shores of the Precambrian continents some 670 million years ago. Coralline fronds arch lazily from the ocean floor, ancestral jellyfish undulate in the currents, marine worms plow through the ooze.
Rolling forward a quick one hundred million years, to the dawn of the Cambrian period, the seascape abruptly changes. Animals suddenly appear cloaked in scales and spines, tubes and shells. Seemingly out of nowhere, in bewildering abundance and variety, the animal skeleton emerges.
Paleontologists have long wrinkled their brows trying to explain why—after at least one hundred million years of soft, serene, multicellular existence—life so hurriedly turned hard. The startling abruptness of it all had troubled Charles Darwin to the point of doubting his own theory of evolution. “To the question why we do not find rich fossiliferous deposits belonging to periods prior to the Cambrian system, I can give no satisfactory answer,” he confessed in his masterwork, The Origin of Species. “The case at present must remain inexplicable: and may be truly urged as a valid argument against the views here entertained.”
Sophisticated hypotheses have been volleying back and forth for decades, some linking the skeletal genesis to changing chemistries of the seas and skies. But wounds discovered in the fossils themselves suggest the sudden hardening of life was more than just a chemical reaction. It was an arms race.
The Cambrian explosion, beginning some 565 million years ago, created in a 10-million-year spree of evolution the blueprint for virtually every major body plan of animal life existing today. It cast the die, in variously deceptive guises, of everything animal—shrimp to giant squid, ant to elephant. And as much as that revolution likely had something to do with rising global levels of atmospheric oxygen (thus enabling turbocharged metabolisms and leaps in body size), it by no small coincidence also came with an evolutionary flourish of lethal weaponry and armored, mobile defense.
The Cambrian was a time for the meek to start watching their backsides. Among the predatory guild was Sidneyia, helmet-headed like a horse shoecrab, with two columns of grasping limbs. The sly Ottoia was a chunky burrowing worm ambushing little shelly creatures from below, vacuuming them through its muscular proboscis—the feat confirmed by whole little fossil mollusks found inside Ottoia’s fossil intestines. By modern standards the Cambrian collection pushes the bounds of credibility. There was Opabinia, anticipating B-grade Martian fauna by half a billion years. Opabinia was an elongated cockroach with five knobby eyes and a serpentine proboscis. The hose nose ended in a mighty claw that evidently cherry-picked careless creatures from the bottom of the sea and delivered them to the mouth. When the paleontologist Harry Whittington of Cambridge University first shared his reconstruction of Opabinia to a gathering of serious-minded colleagues, they broke out laughing.
Among the prey swam the soft-bodied Pikaia, a graceful, undulating ribbon of flesh, unglamorously hunting detritus. In navigating the Cambrian war zone, Pikaia obviously relied on something other than brawn. The relevance of Pikaia’s survival, mentioned here mainly for anthropocentric purposes, stems from its unique wiring. The little worm was internally governed by a single rod of nerves running head to tail, the founding hallmark of the phylum Chordata. The descendants of Pikaia would eventually sprout the fins of fish and fill the oceans, the meaty thighs of tyrannosaurs to stomp across the land. Some would spread the wings of birds and cruise the continents by air. Others would come to wear trousers and classify fossils.
But back to the true heroes of the battleground. Among the Cambrian prey crawled the trilobites, the lovable cockroaches of the sea, hardened and armored to the hilt. The dreamlike Hallucigenia, named for its catalogers’ first impressions, was a multilegged oddity like a centipede, but bristling with spines. There also crept Wiwaxia, a sluglike beast sheathed in a chain-mail suit of armor and—just to make sure—a minefield of dagger blades springing from its back: A headless armadillo crossed with a tailless porcupine.
Some of the fossils that show what these 540-million-year-old armored animals looked like also suggest what they were steeling themselves against. Some of the spines of Wiwaxia appear to have broken and healed. Holes in the armor of certain trilobites suggest they had been bitten.
Bitten by what, nobody could at first imagine. Because the terror of the trilobites was, for nearly a hundred years, still lying in little, innocent-looking pieces. In 1886, Canadian paleontologist J. F. Whiteaves uncovered a fossil from a British Columbia shale quarry, of a spiky creature about three or four inches long—the tail end of something shrimplike, guessed Whiteaves, who, thus stumped, named his creature Anomalocaris, or “odd shrimp.” Another paleontologist, Charles Doolittle Walcott, in a nearby outcrop called the Burgess Shale, later found a circular creature, radially divided into thirty-two segments, pineapple-wise. Walcott named it Petoyia and assumed it a jellyfish.
For decades the two creatures appeared in various artists’ reconstructions of the wondrous Cambrian seascape, each going about its own business. It wasn’t until 1985 that Harry Whittington and his colleague Derek Briggs, upon reexamining the specimens (by then lying dormant seventy years in the bowels of the Smithsonian Institution), decided the two creatures were actually body parts of one another. That four-inch shrimp of Whiteaves’s turned out to be one of Anomalacaris’s claws. That jellyfish of Walcott’s was its mouth. Once pieced together those claws and mouth translated to a monster that in its time approached four feet long, as huge and deadly as anything that had ever moved on Earth. As Briggs and Whittington proudly pointed out, Anomalocaris was the Tyrannosaurus rex of its time.
Anomalocaris glided through the seas on undulating wings like those of a stingray, snatching prey with its hooked claws and crunching them in that deadly pineapple slice of constricting blades. When Briggs and Whittington simulated the bite of Anomalocaris’s circular guillotine, it formed a W, matching suspiciously the outline of wounds not uncommonly found in trilob
ites among various Cambrian fossil beds. The wounds suggested more than a demonstration of shearing force. Those disfigured trilobites, by their very presence, signified creatures that had gotten away. Their battered armor represented not failure, but defenses that had served their purpose. Given that the trilobites were to swim the Paleozoic seas for another three hundred million years, they certainly qualified—by any survival-of-the-fittest criterion—as evolutionary successes.
Which in turn put the monster Anomalocaris in a more benevolent light. If that which didn’t kill the trilobite indeed made it stronger, then Anomalocaris must have been one formidable strength trainer. The Cambrian was a time in which “ways of eating … and ways to keep from being eaten proliferated,” wrote Briggs and Whittington. And Anomalocaris had pushed the limits on both ends.
The Cambrian frenzy was the first unmistakable appearance of the modern complex food web, woven not only with producers and consumers but also consumers of consumers—those superpredators capable of eating all others. It served as the first hard evidence for predation as a major architect of life’s myriad form and function.
Beauty in a World of Wounds
To what degree, the impact of predation, remains the eternal question. It is the one that Geerat Vermeij, an evolutionary biologist who holds an office at the University of California at Davis, has spent most of his life asking.
When Vermeij was nine years old in East Dover elementary school in New Jersey, his fourth-grade teacher brought to class a collection of shells from Florida. Vermeij examined the shells like no other student ever had. He turned them over in his hands, as if manipulating a puzzle, his fingers gliding over undulations, bumps, and ridges, noting the sharpness of edges, the textured exteriors and glassy interiors. There was something altogether different and more exciting about these warm-water shells than the coarse and chalky cockles and razor clams he’d collected as a toddler on the shores of his Netherlands homeland. “How could one explain a shell as odd as the lightning whelk, with a spiral crown of knobs at one end and a drawn-out spout at the other?” he later reminisced. “Why was its interior so stunningly sculptured with smooth, evenly spaced ribs that spiraled away beyond the reach of my fingers?”
Vermeij had never seen such beauty, which had nothing to do with the fact that he’d been totally blind since the age of four. (Born with a rare form of glaucoma, Vermeij had seen only dim shapes and colors before he lost his eyes to the disease.) With his practiced fingers, Vermeij viewed the shells in three-dimensional clarity. Their strength and complexity contrasted so conspicuously with lesser-endowed shells from the cold waters of the North Atlantic. “Why should this be so?”
Immediately thereafter, cigar boxes began filling with the new collection of young Gary Vermeij, self-confirmed conchologist for life. After blazing his way through high school (top in his class), then Princeton (taking Braille notes with a stylus, hiring readers to convey the printed literature), through his graduate careers at the University of Maryland and Yale, Vermeij set about gathering the shells of mollusks from the oceans of the world, Costa Rica to New Zealand, Micronesia to Madagascar.
From his global excursions in search of shells, Vermeij began to develop a curious picture of molluscan architecture. “How odd that all the cold-water shells from New Zealand are so thin,” he thought.
Vermeij would hunt his mollusks by wading slowly through the shallows, toes probing the sand and seaweed for shells, or crawling hand-and-knee upon the shore, acquainting himself with the topography, listening for the rumble of an oncoming wave, the echo of an approaching crevasse. Lifting a specimen, he would run his fingers over the contours, seeing by feeling the lip and protuberances, the aperture, the spiral formations, the ridges and valleys, over a living landscape of calcium carbonate.
The tactile explorations came with their hazards. Vermeij in his wanderings would be stung by a stingray in Panama that as he recalled, was “flapping as it sought in vain to free its barbed tail from my foot.” He would be bitten by a moray eel in Polynesia. In Guam, Vermeij mistakenly caressed a live stonefish, whose dorsal fin is a venomous hypodermic needle capable of inflicting one of life’s most excruciating pains, and occasionally the lesser agony of death.
As Vermeij collected, the artist in him grew to despise the marred and broken shells that so often passed through his fingers. He would toss them aside as one would a chipped plate from a set of fine china. While Vermeij was still in his teens, his brother gifted him with a special shell painstakingly procured from the Philippines. A gem to the untrained eye, under the scrutiny of Gary Vermeij’s fingers it might as well have been a lump of cubic zirconium. “It was with a sinking feeling that I realized the specimen was badly flawed. Running in a jagged line from one end of the shell to the other was a scar, a rough, ugly welt rudely interrupting the otherwise smooth contour of the shells’ pleasing conical shape.” To Vermeij, the scar was “a blemish, an insult that some careless human collector must have inflicted on the specimen.”
It seemed the seas were full of such disappointments. In 1970, while wading tropical tide pools in Guam, Vermeij’s colleague handed him a cowrie, a beautiful piece of polished shell, otherwise ruined by a hole in what had been the animal’s roof. Vermeij sighed and chalked it up to another “crime against nature”—probably the work of waves pounding upon the shallow reef. When his colleague mentioned he’d seen shells broken in this very way by crabs he kept in his aquarium, Vermeij shrugged, filed the thought, and forgot about it.
It wasn’t until two years later, pondering yet another summer of broken shells, that the flawed gift from the Philippines, the wave-battered cowrie from Guam, the crab in the aquarium, flashed to a single coalescing revelation in Vermeij’s mind: those disfiguring scars and welts, those elaborate spines and thick buttresses, those tight coilings and tiny openings—as if the occupants had spiked their house, locked the doors, and huddled in the corner—were neither fashion statements nor the fallout of dumb luck. These were the armaments and injuries of battle.
The persnickety collector therewith swung about-face, eschewing the most elegant of specimens for the roughest of characters, gathering battered old battleships and crippled goners, seeking the wrecked and wounded from around the globe. “Suddenly, all those ugly broken shells that I had previously dismissed as unacceptable specimens became mines of information,” said Vermeij. “Once I recognized the evolutionary importance of scarred shells, I encountered repaired damage everywhere I looked.”
Vermeij found destruction everywhere, but curiously more so in the heavily armored shells of the tropical Pacific than in the lighter fortified shells of the Atlantic. The reason, he first ventured to say in a 1974 issue of the journal Evolution, amounted to the more varied and lethal cast of predators cruising the Pacific sea bottom. The variation in shells was evolution as an arms race.
Back again in Guam, Vermeij resumed exploring his new view of evolution with a small experiment easily appreciated by any little child who has ever, in a moment of sadistic mischief, thrown a grasshopper into a jar of raging ants. Into an aquarium of variously fortified snails, Vermeij introduced two of the reef’s most powerful crabs. Carpilius maculatus, a bulky brute measuring nearly five inches across the back, wielded massive, stubby claws studded with blunt crushing teeth; Eriphia sebana was a smaller but comparably serious crab, with longer and unmistakably lethal claws. The dangerous crustaceans went into the tanks with the defensive snails. And together, Vermeij and his wife, Edith, stood back and listened, waiting for the inevitable explosions of shell.
The crabs would first tend to focus their attack on the rim of a snail’s aperture. Wrestling for position, a pincer would find the point of maximum leverage.
Pow!
Small thin snail meets big powerful crab—an obvious mismatch.
Kapow!
Not to imply that the battles were one-sided bloodbaths. Sometimes the struggles went an hour. Often enough, powerful pincers met impregnable shells. Many a
stubborn mollusk sent an exhausted crab to defeat, the mollusk’s shell battered but intact, still housing one whole and securely ensconced snail. At times it seemed hard to decide which was the underdog.
Among the most heavily armored of snails was a battleship named Drupa morum. The knobby, fortified shell wall of Drupa morum ran two to three millimeters thick, the creature inside secured behind a tight, constricted opening that barred probing pincers. Drupa, the living fortress, sent away many comers to defeat.
But then, there came the she-crab named Railroad Tie. The biggest most awesome specimen of Carpilius maculatus in Vermeij’s collection was nicknamed for the heavy log needed to bar the lid of her aquarium against her escape. Railroad Tie had never met a snail she couldn’t break. In the marquee event of Vermeij’s Coliseum, the unstoppable offense of Railroad Tie was pitted against the drum-tight defense of Drupa morum. On meeting the impenetrable mollusk, the big crab with her extraordinary right claw bypassed the customary perimeter assaults on the snail’s rim. Her claw enveloped the entire shell of Drupa. She started squeezing with a force of some twelve hundred pounds pressure.
Drupa’s shell held.
Where the Wild Things Were Page 4