How predators get past the trickiest of defences

Many clever species are undeterred by porcupine quills, venomous snake fangs, sticky-armed octopuses, and more.

By Jason Bittel
Published 16 May 2022, 10:26 BST
Western_banded_gecko
Western banded geckos have a very specific strategy for killing venomous scorpions.
Photograph by Joël Sartore, National Geographic Photo Ark

When a western banded gecko wants to eat a defenceless cricket or worm, it just gulps it down.

“Pretty boring,” says Malachi Whitford, an ecologist at Clovis Community College, in California.

But if the same gecko goes after more dangerous prey, such as a dune scorpion, it uses a different strategy: It contorts its body as if building up spring-like tension before lunging at the arachnid, Whitford says. Then, as soon as it bites down, the lizard begins thrashing around like a concertgoer in a mosh pit.

“Watching it with the naked eye, it almost looks like the gecko has some sort of medical problem,” says Whitford, who led a study describing the new behaviour in the Biological Journal of the Linnean Society. “It’s just so fast and so violent.”

To investigate more closely, Whitford and colleagues caught several wild geckos and scorpions and filmed the reptiles’ attacks in the lab with a high-speed camera. The footage suggests the thrashing may be an attempt to break scorpions’ delicate stingers or prevent them from delivering much venom. Or the geckos may simply be trying to kill the scorpions. (See pictures of amazing amphibians.)

Video: Cannibal Scorpions Fight to the Death

Whatever the case, the geckos have embraced a behaviour that allows them to feed on a very dangerous food source, Whitford says.

It’s only one example of how predators get past even the most formidable defences of would-be prey.

Raptors vs. wasps: battle for the treetops

Taking on a single stinging arachnid is not for the faint of heart. Then again, squaring off against a colony of hundreds or thousands of venomous airborne insects is next level.

Red-throated caracaras are social, medium-size raptors that work together in lowland forests in Central and South America to attack wasps of numerous different species. They often pursue those in the tribe Epiponini, which includes the so-called warrior wasps. 

First, the birds take turns dive-bombing the wasps’ nests, which range from grapefruit-size to larger than a watermelon. Each assault means risking painful stings, but eventually the caracaras knock the structure to the forest floor. The birds then gobble up protein-rich wasp larvae as the adult wasps flee.

“The red-throated caracaras are exploiting what’s known as the absconding response,” says Sean McCann, an independent natural historian from Vancouver, British Columbia, who studies animal behaviour. “Basically, that’s when the wasps abandon their nest in the face of an unbeatable foe.”

Caracara attack squads are so effective at crippling and devouring wasp nests that it was believed that the birds were equipped with a wasp-repellent chemical. But McCann’s research has disproven that theory; although the birds do suffer stings, their hit-and-run technique seems to limit the damage.

Flipping the script on formidable foes

When a weasel-relative known as the fisher wants to eat a North American porcupine, it dances circles around the prickly creature, dashing in every now and then to bite at its eyes and nose. After a while, the porcupine becomes disoriented, and the fisher can flip it over and tear into its soft, un-quilled underside.

Turning well-fortified creatures over is a common strategy that has evolved independently in many animals. For instance, titan triggerfish in the Indian and Pacific Oceans perform a similar manoeuvre to get at the fleshy underbelly of sea urchins. Sea otters love to eat urchins too, but they solve the problem by bashing the echinoderms with rocks until their shells crack

Bottlenose dolphins also use a combination of brains and brawn to prey on sticky-limbed Maori octopuses, wily adversaries that can kill dolphins by smothering their blowholes, and, in one notable case, by latching onto the dolphin’s larynx—causing asphyxiation. 

The key is to disable the octopus before trying to eat it. Dolphins accomplish this by slapping the cephalopods against the water’s surface and tossing them high into the air. This causes massive trauma—and even can tear off their dangerous limbs.

The leatherback turtle’s armoured oesophagus 

The leatherback turtle doesn’t need any fancy moves. When leatherbacks want to slurp down a venomous jellyfish—they favour lion’s mane jellyfish—they have the advantage of a six-foot-long oesophagus, says Kara Dodge, a sea turtle expert at the New England Aquarium, in Massachusetts.

Every inch of the oesophagus’s surface is covered in long, spiky protuberances, or papillae, each with a hard tip that allows the turtle to drag gelatinous prey down to its stomach, mashing the meal up along the way. 

“It’s basically a spiny conveyor belt for jellyfish,” Dodge says. “And it allows them to just continuously feed. We filmed them eating over 120 jellyfish in two hours.”

It’s unknown if the turtles have some immunity to jellyfish venom, as do garter snakes that eat poisonous newts, opossums that feed on rattlesnakes, and grasshopper mice that attack bark scorpions. 

“People have hypothesised there might be some mechanism for the turtles to neutralise the venom as they’re eating jellies,” Dodge says, “but nobody has actually figured out what that mechanism might be.”

Whatever it is, it’s working: Leatherbacks are the only turtle with a diet consisting solely of this gelatinous prey.

The snake that eats other snakes

You might think venomous snakes such as cottonmouths and rattlesnakes in the longleaf pine forests of the southeastern U.S. have little to fear. But there’s another serpent in these woods that sends them slithering.

It’s the Eastern indigo snake, which can grow to about eight feet, and has big, black scales with an iridescent shimmer. Their diet includes a variety of animals, from rodents and birds to frogs and turtles, but what indigos like most is to eat other snakes. They accomplish this without venom or constriction. (Read about cobras that eat other cobras.)

“They typically target the head or neck of other snakes, chewing on the prey item until it is subdued enough to swallow,” says Houston Chandler, science director of the Georgia-based Orianne Society, named after co-founder Thomas Kaplan’s daughter. “Because indigo snakes are so big, they can easily overpower smaller snakes, dragging and pushing them around at will.”

Recent research suggests that indigo snakes also may have some immunity against venom in case they get bitten in the fray.

All this goes to show that defences such as spines, suckers, armour, and even venom can’t make an animal invincible. Just as Superman is vulnerable to Kryptonite, evolution has a way of levelling the playing field.

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