Animal Weapons

by Douglas J. Emlen

  It was a new style of gun, rather than sneaky fire ships, that brought the age of the sailing battleship to its close, however. Advances in artillery, particularly rifled barrels and exploding shells, rendered these warships obsolete.28 For the preceding three hundred years, naval guns had all been smooth-barreled cannons firing solid iron balls.29 Guns and balls got bigger, but the technology remained the same. By the 1850s, however, spiral grooves were cast into the bores, or barrels, of cannons, causing projectiles to spin. “Rifle-bore” cannons struck targets with far greater accuracy and at longer ranges. Around the same time, cannonballs were replaced by pointed shells filled with explosives, utterly changing the type of damage inflicted in naval battle.

  Solid iron balls smashed holes into hulls, toppled masts, and impaled crews with flying shards of timber. But it took a lot of iron balls to sink a ship. For this reason, bigger ships were better in a brawl. They packed more cannons and, therefore, fired a bigger broadside. Thick wooden hulls and bigger broadsides rendered the largest ships invulnerable to all but an equally matched rival, precisely the conditions conducive to an arms race.

  Explosive shells cheated. They blew metal shrapnel everywhere, rupturing hulls beneath the waterline and triggering catastrophic fires.30 Wooden hulls simply could not withstand the destructive impact of exploding artillery. Just a single direct hit could sink a ship. Furthermore, since these new guns could be mounted on small, inexpensive vessels, they undermined the traditional rules of engagement. All but overnight the most impressive warships became bulky targets.

  The solution was metal armor shielding the sides of ships, but steel hulls weighed too much to power with sails.31 The arms race between sailing vessels was over. Navies were at an impasse until steam-powered screw propellers released ships from the weight constraint, launching a new arms race between ships powered by propellers instead of wind.32

  Epitomized by HMS Dreadnought, a sleek and imposing new warship took center stage. Sheathed in armor and sporting large, rifled cannons on rotatable turrets, these new “ironclads” killed from afar. Once new aiming techniques had been perfected, ironclad battleships could sink opponents from several miles away.33 Fights no longer unfolded yardarm-to-yardarm, but duels between these great ships persisted nevertheless, and the nature of these new guns created an environment where bigger was better—more than enough to trigger a race.

  Armor resisted small-caliber shells, which gave ships with bigger guns an advantage. Bigger guns, in turn, selected for thicker armor, and both required bigger ships to carry them. At the same time, revolutions in engineering were advancing the power provided by steam propulsion. The race for speed was on. Navies rushed to develop ships that were bigger, faster, more heavily armored, and sporting larger guns than ships in rival navies. The burst of battleship construction that followed has been described as one of the most rapid and prolific arms races of all time.34

  At first Britain, France, Germany, Russia, Italy, the United States, and Japan all launched into massive shipbuilding campaigns but, by the beginning of the twentieth century, the sheer cost and staggering sizes of the fleets caused the race to coalesce around just two naval superpowers, Britain and Germany.35 By the start of WWI, dreadnoughts had evolved into larger, faster “superdreadnoughts,” and both countries managed to assemble dozens of these outrageously expensive ships.36

  As impressive as these new navies appeared, they were threatened from the start by cheaters. Fire ships had evolved into torpedo ships—small, fast boats able to slip up close to a battleship and release motorized torpedoes. Bulky battleships could not maneuver fast enough to evade these little pests, so navies created destroyers—small, specialized warships designed to intercept and sink torpedo boats.37 Soon, destroyers themselves carried torpedoes, making them useful for offense as well as defense.38 Just as ant colonies produce both big-headed, powerful soldiers and smaller, mobile workers, fleets now spawned big ships and little ships designed around specialized tasks.

  But the sneakers kept getting better. Soon it was possible to carry torpedoes in underwater ships, firing them without ever breaking the surface. The ultimate sneaks, submarines, could creep up to the biggest battleships and sink them from below,39 undermining the prestige and tactical effectiveness of a navy’s most powerful weapons. Like peasant farmers with crossbows, submarines shattered the traditional rules of engagement. Battleships became ungainly targets; their greatest strength, a liability. The only way to use them was to surround them with other ships, gobbling up fleet strength and limiting movement since each behemoth now had to be escorted by a gaggle of destroyers and escorts running interference.

  The Germans apparently realized they would never catch up with Britain’s naval construction frenzy, so they secretly shunted funds from battleships to submarines, assembling a fleet of stealth U-boats.40 Ironically, Germany used its U-boats to greatest effect not by targeting and sinking naval battleships, which were now protected by squadrons of destroyers, but by sinking merchant ships crossing the Atlantic unprotected.41 There was no way the British (or any) navy could protect all of these merchant ships. They became easy targets for the submarines, crippling transport of war materials and personnel and undermining the Allied war effort.

  Submarines, in turn, spawned still another form of sneaking. The British cloaked military ships to look just like helpless merchant vessels. “Q-ships,” as they were called, were one of the most closely guarded secrets of WWI.42 The trick was to lure submarines in close and induce them to surface. Subs carried only a limited number of torpedoes, so if the merchant vessel appeared helpless enough, a submarine might surface to sink the ship using deck-mounted guns, saving precious torpedoes for a later target. Sometimes Q-ships would feign sinking, releasing smoke while crew members abandoned ship in lifeboats, enticing the U-boat to surface to finish the job. The moment the sub breached, remaining crew on the Q-ship dropped panels along the hull, revealing hidden deck guns and opening fire. The Q-ship double sneak was a bold and clever strategy, but it proved exceedingly dangerous and, ultimately, cost-ineffective. Q-ships sank fourteen German submarines during the war, but twice that many Q-ships were lost in the process.43

  Submarines were the ultimate “sneaks” in naval warfare. Small and invisible, they could sink even the largest of battleships.

  By 1914, it was clear even to the British that despite their grandeur, battleships were not going to prove decisive in battles. They’d been designed to fight other battleships, but such engagements almost never materialized and, as deterrents, they had become obsolete.44 Although battleships remained a part of naval fleets for many years afterward, their prestigious role as monarch of the seas was over, and the few that remained in service ended up supporting a newer and better weapon, the aircraft carrier.45

  In the end, the fate of all weapons comes back to benefits and costs. Early in arms races the payoffs for big weapons may soar. But circumstances change. Costs climb and cheaters invade, gouging profits until big weapons reach a point that’s unsustainable: the rewards no longer justify the expense. From that point forward, they’re just a liability.

  * * *

  The sunset was beautiful, as it nearly always was on Barro Colorado Island. Colorful parrots squawked as they converged from all directions, piling into a communal roosting tree at the edge of the water. A keel-billed toucan crossed the clearing in front of us with a soft whoosh. It was February 1992. I’d completed my stint in the Panama forest and was preparing to return to normal life as a graduate student. All the beetles were measured; the ant farms disassembled; and thousands of plastic tubes sat boxed and secure in deep storage. My lab was clean and my bags nearly packed. For almost two years I’d lived and worked at the Smithsonian research station on BCI, hanging with a crowd of biologists all working diligently to understand the details of life. Now it was time to go home.

  Several of us relaxed on a porch overlooking the canal, beads of precipitation dripping from our ice-cold bottles of beer
. Big ships were a regular sight, as boats traversed from the Atlantic to the Pacific or vice versa. Most were boring box boats, cargo carriers stacked to the brim with metal crates. Every now and then a cruise ship would appear. But the most exciting by far were the warships. This evening an entire fleet of the U.S. Navy glided quietly by—destroyers, cruisers, and, best of all, a battleship—a slate-gray monstrosity, awe-inspiring with its gigantic guns, bristling with antennae, radar, and satellite dishes. U.S. battleships were the largest vessels able to fit into the canal, we were told. At almost nine hundred feet long and just over one hundred feet wide, Iowa-class battleships had only eleven inches to spare when they squeezed into the locks.

  I’ll remember that night for the rest of my life, because I woke to a shattering explosion. In a flash of blinding light I was thrown six feet from my bed, hitting the wall and then crumpling to the floor. I sat there, shaken and aching in the sudden darkness, sure we were at war; my first thoughts were of the battleship. Why would it fire at the field station? This was not quite as preposterous as it might sound. After all, just twenty-five months earlier the United States had invaded Panama, ousting Manuel Noriega in Operation Just Cause. Bullet holes still marred the walls of buildings in Gamboa a mere ten miles away.

  Of course, we were not at war; the battleship was just a coincidence. Bolted to the other side of my skimpy dorm room wall was a hundred-foot-tall radio tower, and although it was supposed to be grounded, lightning had struck it that night with enough charge to zap me to the floor—one of the reasons, no doubt, that the building was dismantled a few years later and the clearing returned to the forest.

  I didn’t appreciate it at the time, but that glorious ship, cruising proudly into the fading light, was the USS Missouri, the last active battleship in the world. She was decommissioned a month later that same year. I had witnessed the final voyage of the very last battleship of them all.

  PART IV

  PARALLELS

  The first three sections of this book focus on animal weapons, plucking snippets from military history as needed to make a point or to illustrate a parallel. Just how far do these parallels extend? The final chapters delve more deeply and completely into humanity’s greatest arms races, revealing startling similarities with animals, as well as important differences.

  12. Castles of Sand and Stone

  African army ants, like their Central and South American relatives, are ferocious predators. Jaws of the largest soldiers can snap through a pencil, but the true force of these ants lies in their numbers. A raiding swarm twenty million strong pours forth from its nest, advancing in a column through the bush. The leading wave of ants is so thick that it drives everything that can to move out of its way. Anything that doesn’t faces a horrific death. Animals overtaken by a swarm are sliced into ant-size chunks, hoisted by workers, and carted piecemeal back to the nest. Streams of workers carry the carnage of a raid along ant superhighways—cleared trackways coalescing like giant, exposed blood vessels pumping blood back to a heart. As they race homeward with their loads, the workers are protected by walls of soldiers flanking the sides of the trackway and, in some places, covering it entirely with a latticework of their intertwined bodies.1

  The Kenyan Maasai love “siafu,” as they call these ants, since they scour through houses cleaning out cockroaches, detritus, other ants, and even rats. The Maasai also use siafu as emergency sutures, in precisely the same way that I did years ago in Belize. But African army ants have a dark side. Occasionally, livestock get trapped and, when prevented from escaping, they, too, are devoured. Coops full of chickens, tethered goats, and cows can be stripped to bones in just a few hours. Sometimes even elderly or drunk people fall victim. Eighteenth-century explorers describe the use of army ants as a cruel form of execution, binding criminals to a stake in the path of an advancing swarm.2 But the most tragic human fatalities involve infants left unattended in their cribs. Ants march into a nursery through an open window, swarm up the sides of the crib and pour into the mouth and lungs, suffocating the baby as its flesh is stripped away. As many as twenty infants every year still succumb to siafu.

  In January 2005, Caspar Schöning, now a biologist at Freie Universität Berlin, watched an army ant raid unfold at the edge of a meadow behind the field station where he was staying. Schöning had completed his doctoral studies the year before, focusing on the behavior of army ant swarms; he was in Nigeria with renowned nature photographer Mark Moffett to photograph a raid. What they captured was highly unusual. At first the ants carted back pieces of beetle and cricket—typical fare—along with shards of spider and moth, the pieces bobbing back and forth as the ants marched. But then a string of soft, white grubs began to appear. The ants were carrying termites. On and on the ants came, carting pale termite bodies back to the nest. Thousands and thousands of them streamed past. Big-headed soldier termites flowed by in pieces. Heads carried by one worker, legs by others, abdomens by still others. Soon the termite brood began to appear, tens of thousands of eggs and larvae shuttled along an endless conveyor of running ants. Schöning and Moffett estimate that more than half a million termites were snatched that night, including the colony’s offspring.3

  That the army ants had successfully plundered a termite colony was surprising, because siafu essentially never eat termites.4 In fact, Schöning and Moffett’s published account of this raid remains to this day the only documented example of its kind. Army ants are not exactly picky about their diet choices—they’ll eat anything from spiders to cows, and everything in between—and termite colonies litter the landscape, making them one of the most abundant sources of prey in the area. Termites are soft and plump, loaded with lipids, protein, and carbohydrates, and, except for the soldiers, they are utterly defenseless. When they’re exposed aboveground, just about everything eats them. All of which makes the omission of termites from siafu diet striking. The secret to termite safety: fortresses.

  Termite mounds are magnificent structures.5 The species raided that day by siafu, Macrotermes subhyalinus, erects castles of sand and mud towering ten feet above the ground—two thousand times taller than the termites themselves. The conical base of a mound may be four feet across, but it constricts as it rises to a central spire, and the top eight feet jut skyward like a stovepipe. On the outside is a solid wall. Meticulously erected by millions of workers, the wall is built from grains of sand mixed with excrement and spit to form a cement. Baked by the sun, the outer wall is as durable as kiln-fired brick. It takes a sledgehammer or an ax to breach the surface, and it’s not uncommon for sparks to fly with each strike.

  If you manage to smash through this wall, you’ll find empty space on the other side. No termites yet. Inside the outer wall sits a second wall. This inner wall is separated from the first wall by the insect equivalent of a castle’s moat—a no-man’s-land. This air-filled space forms a six-inch gap, and only after breaching the second wall will you get to the colony proper. The termites themselves enter or exit through tiny little gates, a half dozen termite-sized tubes that extend through the no-man’s-land to the outside world. These tubular gateways have rock-solid walls, and they’re guarded by masses of big-headed soldiers.

  At the core of the fortress a city of insects bustles.6 Millions of workers flow back and forth between dozens of coconut-sized chambers. Like coconuts, each chamber is encased in a rigid protective shell. They stack together in the soil in a bundle connected by a maze of tunnels and sheltered from the rest of the world by the concentric rings of the outer walls. Some of the chambers house food for the colony, a fungus that the termites cultivate in the cool darkness belowground. Others are nurseries packed with eggs or larvae. At the heart of the complex lies the most protected chamber of all. Like the keep of a medieval castle, the chamber housing the queen is set apart from the rest, accessed only by a single opening so small that the queen herself could not possibly fit through.

  Termite queens are as specialized for reproduction as the soldiers are for battl
e. Egg-laying machines, queen termites have bloated, pulsating abdomens thicker than my thumb, and they lay thousands of eggs each day. Minuscule workers wait beside the queen, plucking new eggs from her body as they emerge and shuttling them off to nurseries. The queen is so obese that she literally cannot move. Completely dependent on the workers to feed and tend to her, and irreversibly ensconced in her inner ward, she’ll live for ten years or more without ever leaving the protection of the royal chamber.

  Millions of busy workers and balls of growing fungus consume huge amounts of oxygen and release carbon dioxide. They also generate heat, and both must be dissipated from the colony for it to thrive. Remarkably, the architecture of termite mounds accomplishes this as well. Although hard as a rock and impenetrable to other insects, the walls of termite mounds are infused with hundreds of millions of microscopic pores. The walls breathe, allowing oxygen to enter and carbon dioxide to escape. Wind passing over the chimney—or even directly through the walls—pulls stale air out of the colony and replaces it with fresh, oxygenated air. The double-walled design also works like an insulator, keeping the colony inside at a constant and cool temperature.7

  Termite mounds provide protection, storage, and temperature control, but their primary function is protection. Impenetrable walls shelter each colony from attack. Short of a Godzilla-like monster ripping the top off—which for Schöning’s colony meant the claws of an aardvark—the only way into a mound is through one of the tiny, heavily protected gates. The heads of the termite soldiers who guard these gates are so big that they can barely walk, and eyes and other vulnerable organs are long gone. Giant jaws agape, soldiers waddle into the fray, lunging in droves at any insects that attempt to pass. Snapping jaws lock onto legs, sever heads from bodies, and snip off antennae, reducing invaders to jumbles of parts. At the same time, worker termites seal off the gates from within. The moment attacking ants are detected, an alarm signal spreads and workers flock to the gates. Like lowering wrought-iron portcullises to block entry to a castle, these tiny masons cement sand and mud into each tunnel gate until it is completely plugged. Only later will they reopen the gates, long after the raiding ants have marched on.