Extreme Nature. Mark Carwardine
© Thomas Eisner & Daniel Aneshansley/Cornell University
In the world of insects, ants can overcome almost anything. But they don’t always have it their own way. Bombardier beetles deliver an anti-ant surprise that is positively explosive. An ant, a spider or any other predator that, say, clamps on to a beetle’s leg with hostile intent instantly finds itself blasted with a chemical spray that’s as hot as boiling water.
So how does a small, cold-blooded creature manage to do this? Pure chemistry: in the rear of its abdomen are two identical glands lying side by side and opening at the abdominal tip. Each has an inner chamber containing hydrogen peroxide and hydroquinones and an outer one with catalase and peroxidase. When chemicals in the inner chamber are forced through the outer one, the chemicals react together, and the beetle has effectively created a bomb.
The resulting vapour, now containing the irritants known as p-benzoquinones, explodes from the end of the abdomen with a bang that’s audible to a human and a temperature that’s scalding to the would-be predator. What’s more, the beetle can rotate its abdomen through 270 degrees in any direction, so that it can aim with absolute precision, and if 270 degrees isn’t enough, it can shoot over its back, hitting a pair of reflectors that will ricochet the spray at the extra angle needed. Scientists find bombardiers fascinating because they’re the only animals known to mix chemicals to create an explosion.
| NAME | golden poison-dart frog Phyllobates terribilis |
| LOCATION | Pacific rainforests of Colombia, South America |
| ABILITY | producing the most deadly poison of any animal |
© Chris Mattison/FLPA
This tiny frog uses toxic chemicals as a defence in its body and is therefore technically poisonous (venomous animals inject toxins via a weapon – a tail, fang, spine, spur or tooth). The toxin is effective only when the frog is attacked, and since the frog doesn’t want to be harmed, it sports a brilliant yellow or orange colour to warn predators of extreme danger.
In fact, this most poisonous of frogs is possibly the most poisonous animal in the world. The toxin is in its skin – you can die even by touching it – and there is enough in the skin of one animal to kill up to 100 people. Though the frog has been known to science only since 1978, inhabiting just one area in Colombia, the Chocó indians have known about it for generations, using its skin-gland secretions to poison their blowgun darts and kill animals in seconds.
The golden poison-dart frog gets most of its batrachotoxin (meaning frog poison) from other animals, probably small beetles, which in turn get it from plant sources. Captive-bred frogs, by comparison, never become toxic, presumably because they aren’t fed toxic insects. The frog is active in the day, having few predators except a snake, that has become immune to the toxin. Surprisingly, birds have been discovered in New Guinea with the same batrachotoxin in their skin and feathers. The likely link has been tracked down to a small beetle, similar to the New World beetles, which also contains batrachotoxins.
| NAME | New Caledonian crow Corvus moneduloides |
| LOCATION | Pacific island of New Caledonia |
| ABILITY | thinking up ways to get at hard-to-reach food |
© Ron Toft
Quite a few non-human animals, from sea otters to woodpecker finches, use tools and sometimes even craft them. It’s usually assumed that the animal that is best at this is our nearest relative, the chimpanzee. Chimps use rocks to crack nuts and cut and fashion twigs or blades of grass to fish in mounds for termites. These are ‘cultural’ skills, practised only by certain groups of chimps and taught to youngsters. The skills are certainly sophisticated: an anthropologist once spent several months with a group of chimps trying to learn the art of termite fishing and finally achieved the proficiency, he reckoned, of a four-year-old chimp novice.
For pure innate, instant ingenuity, though, it would be hard to top the New Caledonian crow. In an experiment in a lab, meat was put in a little basket at the bottom of a perspex cylinder – and a female crow, Betty, was given a straight piece of wire. Holding the wire in her beak, she tried to pull the basket up, and failed. Then she took the wire to the side of the box holding the cylinder, poked it behind some tape and bent the end into a hook. She went back, hooked the basket, and got the meat. When the experiment was repeated, Betty did roughly the same thing, but with the addition of two different tool-making techniques. In the wild, New Caledonia crows make food-hooks out of twigs, by snipping off all but one protuberance. But bending a piece of wire … how would a crow know?
| NAME | luminescent bacteria Photorhabdus luminescens meets nematode Heterorhabditis bacteriophora |
| LOCATION | inside a caterpillar or maggot |
| ABILITY | combining forces to eat larvae alive |
© Randy Gaugler
This is a slow and horrible way to die. A worm-like creature, a nematode, goes on the hunt by squirming through the soil in search of an unsuspecting insect grub, or larva. It’s not particularly fussy and likes anything from a weevil to a fly maggot, but it may take months to find a suitable victim. When it does, it penetrates the cuticle of the larva, either through an opening such as a breathing pore or by hacking a hole with its special ‘tooth’. Once inside, it sets free more than a hundred bacteria from inside its gut, which start producing deadly toxins, digestive enzymes and antibiotics.
The bacteria are luminescent, and as they multiply, the grub takes on a deathly glow. The nematode then starts feeding on the bacteria and the remains of the grub corpse, which is kept free from other competing microorganisms by the antibiotics. Finally, it changes into a hermaphrodite female, laying eggs in the cadaver that hatch into both male and female nematodes.
Yet more of her eggs develop inside her, and when they hatch, the juvenile nematodes eat their mother. They then mate and produce their own eggs. It’s at this point, two weeks later, that the grub finally breaks up and thousands of young nematodes (each carrying the bacteria in their guts) exit into the soil. The bacteria and the nematode can’t exist without each other – a gruesome partnership but one that humans have joined, helping the little nematodes spread by deliberately releasing them to hunt down garden pests.
| NAME | great hammerhead Sphyrna mokarran |
| LOCATION | tropical and warm temperate seas |
| SKILL | hunting with electricity |
© James D Watt/imagequest3d.com
All sharks can, to some extent, detect other creatures by sensing the minuscule amount of electricity they create simply by virtue of being alive. In most sharks, this sense is principally an adjunct to more dominant senses (usually hearing, smell and vision) and is particularly important in the final split-second