• Choose a category
• All
• Classic-Fiction

By Root 503 0

the neighboring tree to form a fingerlike mass jutting into the air. After an hour, the wind rocked two branches close enough for the workers at the end of the “fingertip” to grasp a twig on the opposite tree. As the trees swung apart, the chain pulled taunt and the bridge from one tree to the next was renewed.20 The ants had created an easy route to avoid the long march down to the ground and then over to and up the second tree. The next morning, the ants were still there, strung together and straining under the weight of a small cicada being carried across their bodies by a team of their nestmates. Being part of such a skywalk has my vote as the worst job in an ant colony.

FLOATING AND SWIMMING

Much of my time in the tropics has been spent in one of two uncomfortable situations: wedged between branches high in a tree or traveling along the ground in a downpour so warm and torrential that I felt like I was suffocating. Luckily, these are superb times to ant-watch, with the goal of understanding an ant’s physical world. There’s a rule of thumb among biologists: living things in temperate zones suffer more from physical events such as cold spells, while creatures in the tropics are more vulnerable to biological threats, such as predators or competitors. Flooding is an exception to the rule in that it is a physical problem for ants no matter where in the world they live.

Flooding can be serious even for canopy ants. Southeast Asian bamboo-dwelling Cataulacus muticus ants use their helmet-shaped heads as rain shields to block the holes that allow access to their nests. If a chamber still floods, there’s an unusual backup plan: hundreds of workers drink their fill, climb outside, lift their abdomens high, and communally pee. The removal of one milliliter of liquid requires the ants to relieve themselves a total of 1,515 times.21 Other species bail out their nests by spitting the water away with an audible click of their mandibles or smearing it on the ground outside their nest.22

Weaver ants’ leaf nests shed water, but having been in a tent that collapsed from the force of a cyclone, I know firsthand what a wild ride they experience during heavy storms.23 Meanwhile, any ants caught outside take a beating. When a shower begins, the workers that had been climbing to their nests turn around and walk in reverse, with their legs spread wide, giving their adhesive toe pads a better grip. If the rain turns torrential, they find shelter under a branch or, failing that, aggregate in clumps that grow in size and compactness until as many as a hundred ants are huddled together, limbs entwined, holding tight to the bark to keep from being washed away. As soon as the rain slackens, they disentangle themselves and scurry home, head forward.24

Ants on the ground have it worse. Within a marauder ant nest, things get soggy as water swirls through passageways, though the entrances are often higher than the surrounding ground, which helps keep water out. Marauder ant workers caught in the rain will, if they’re lucky, make it back to the nest or find a sunken or underground section of a trunk trail to retire to. As a last resort, the ants withdraw beneath the leaf litter, though this is likely to become submerged as puddles form. Once I observed a leaf break free of the bottom, dislodged by a bubble that then burst to the surface, with soused ants swirling into view. Apparently, the workers had found safe haven in an air pocket below the leaf. The unlucky ones drowned.

Once the rain stops and the puddles soak into the earth, the marauder ants emerge from their hideaways to reorganize into columns. Heavy downpours obliterate physical evidence of a trail’s existence and must wash some of the pheromones away, too. A trail reemerges as the workers locate each other, linking up in a route that usually manages to follow the old one closely. Workers that fail to find their nestmates become lost and die.

The red imported fire ant of the American South—originally from floodplain habitats in Argentina—survives deluges by forming a raft of thousands