Extreme Nature

Mark Cawardine

With Rosamund Kidman Cox

Copyright

HarperCollins Publishers Ltd.

77–85 Fulham Palace Road

London W6 8JB

www.harpercollins.co.uk

First published by HarperCollinsPublishers 2005

Text © 2005 Mark Carwardine

Commissioning Editor: Helen Brocklehurst

Art Director: Mark Thomson

Editor: Rosamund Kidman-Cox

Design and layout: Richard Marston

Proofreader: Kate Parker

Index: Hilary Bird

Editorial Assistant: Julia Koppitz

Colour reproduction by Dot Gradation, Essex

Mark Carwardine asserts his moral right to be identified as the author of this work.

A catalogue record for this book is available from the British Library.

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Source ISBN: 9780007207688

Ebook Edition © OCTOBER 2014 ISBN: 9780007596614

Version: 2014-10-13

Contents

Cover

Title Page

Copyright

Introduction

Extreme Abilities

Extreme Movement

Extreme Growth

Extreme Families

Keep Reading

Index

Acknowledgements

About the Publisher

Introduction

Extreme Nature is about some of the most intriguing, supernatural, out of the ordinary and extreme plants and animals on the planet. A fish that can change sex, a frog that gives birth through its mouth and a flower that smells so bad it makes people faint are in the motley collection of weird and wonderful creatures included in the book.

If proof were ever needed that fact really is stranger than fiction, then look no further than the natural world. Did you know, for example, that a bombardier beetle can blast a chemical spray that’s as hot as boiling water? Are you aware that a castor bean produces a toxin 6,000 times more deadly than cyanide? And have you ever wondered about the three-toed sloth, which has just two modes of being: asleep and not quite asleep?

It would have been hard for a science fiction writer to dream up some of the most bizarre creatures and wacky behaviour described in this book. Imagine an animal that squirts up to a quarter of its own blood at its predators – that’s the Texas horned lizard. There is a frog that can withstand being frozen to –270°C (–454°F) and a moth with a 35cm (14in) tongue. A fish that can inflate itself to become a spine-covered sphere three times its original size may sound like a character from The Hitchhiker’s Guide to the Galaxy, but it really does exist, in tropical seas around the world, in the form of the pufferfish.

One of the richest environments for such peculiar and eccentric wildlife is the sea. This is where scientists first discovered the coelacanth, for example – a strange-looking fish that was thought to have gone extinct 65 million years ago, but is now known to be alive and well and living in the western Indian Ocean. The sea is where we first set eyes on a remarkable octopus that lives a life of deception, by disguising itself as anything from a flounder or a jellyfish to a sea snake. And in the cold, dark ocean depths scientists have found shrimp-like creatures thriving 11 km (6.8 miles) below sea level. But the sea is also the most unexplored region of the world and studying its wildlife can be about as difficult and challenging as exploring outer space. Even now, there are probably huge animals lurking beneath the ocean waves as yet unseen by human eyes – and untold numbers of smaller ones. But with the help of space-age research techniques and equipment, such as deep-sea submersibles and remote-access vehicles, we are just beginning to understand the true extent of alien-like life on our own planet.

There are more outlandish creatures to discover on land, too, though many of them are likely to be the natural world’s tiddlers and relatively hard to find. But the fact that we’ve already unearthed plants that eat animals, insects capable of walking on water and frogs with baggy skin just makes scientists determined to search for new species of plants and animals and ever-more extravagant forms of behaviour. It’s hard not to wonder what secrets have yet to be unravelled in the treetops, deep underground, in hidden corners of remote tropical rainforests, or under the glare of a microscope.

Extreme Nature was written with the invaluable help of over 150 such scientists working in all corners of the globe. With their generous assistance, in just a few sentences it’s been possible to summarise some of the highlights of many years, sometimes decades, of research. Thanks to them, if you’ve ever wondered which animal has the best colour vision, if a millipede really does have a thousand legs, how fast a falcon can swoop, or which is the world’s most dangerous snake, this is the place to look.

Any study of extreme nature is inevitably full of surprises, and when it comes to superlatives, there is always another record-breaker just around the corner. But while there’s little doubt that few of the records we’ve included are absolutes, in one way or another all animals and plants have something exceptional about them that deserves our attention. It’s certainly been enormous fun corresponding with so many experts in so many different fields and, with their guidance, making the final selection.

Ultimately, the aim of the book is simply to revel in these other-worldly creatures and their outlandish behaviour. We hope you enjoy being wowed by some of their exploits.

Extreme Abilities

Most devious plant · Strangest boxer · Most explosive defence · Most poisonous animal · Most ingenious tool-maker · Most gruesome partnership · Best electro-detector · Stickiest skin · Deadliest plant · Biggest blood-sucker · Keenest sense of smell · Most enthusiastic singer · Most gruesome tongue · Most inquisitive bird · Biggest drug-user · Most painful stinger · Slipperiest plant · Heaviest drinker · Best mimic · Most formidable killer · Best architect · Most painful tree · Loudest bird call · Deadliest drooler · Most sensitive slasher · Smelliest plant · Most impressive comeback · Hottest animal · Most shocking animal · Coldest animal · Most talkative animal · Most bizarre defence · Smelliest animal · Slimiest animal · Keenest hearing · Stickiest spitter · Best colour vision · Most dangerous snake

Most devious plant

NAME | ghost orchid Epipogium aphyllum
LOCATION | North and Central Europe east to Japan
ABILITY | cheating a fungus

© Jeffrey Wood/Royal Botanic Gardens, Kew

The natural world as we know it is built on partnerships. But in all societies there are cheats, and plants are no exception. Most green plants would be unable to exist without the help of fungi, which provide them with food-exchange partnerships. In fact, the invasion of the land by plants – algae – was probably only made possible by such partnerships. It has even been suggested that early land plants developed roots just so they could join forces with the fungal roots, or hyphae.

Most plants are proper partners, giving the carbohydrates they manufacture with their chlorophyll. Some, notably orchids, have such a close partnership that they don’t even bother to produce proper food packages to accompany their embryos into the world, instead relying on fungi in the soil to provide the food needed for germination and early growth. This allows an orchid to produce lightweight, microscopic seeds – millions of them.

Some orchids, however, have become cheats: they use fungi that have partnerships with trees, and they never give anything in exchange. Via fungal hyphae, these orchid vampires tap into the trees, siphoning off nutrients. The give-away is often the fact that they have stopped producing chlorophyll and so aren’t green but a rather sickly pinkish cream, like the ghost orchid, or brown, like the bird’s-nest orchid. Some, such as western coralroot, are blood red or even purple. The drawback is that, without the fungus, the orchid will die. And one day a fungus might just evolve a way to get its own back.

Strangest boxer

NAME | boxer crab, or pom pom crab, Lybia species
LOCATION | Indian and Pacific Oceans
ABILITY | packing a punch with anemone gloves

© Roger Steene/imagequest3d.com

Mutual relationships in the sea are common. A famous one is between a hermit crab and an anemone, where the former gains protection from the anemone’s stinging nematocysts, and the latter gets leftover food. Boxer crabs seem to have taken this a stage further. These tiny crabs – their carapace measures just 1.5cm (0.6in) – are prey to many animals. Their defence is to wield minute, stinging anemones on specialised claws. A jab with a ‘glove’ can cause pain (even to a human) or death and seems an effective defence – one boxer has even been observed seeing off a blue-ringed octopus. The anemones are also used in crab-to-crab boxing. But such fights are ritualistic, and boxing opponents hardly ever touch each other with their anemones, grappling instead with their walking legs.

When a growing boxer has to moult, it must put down its anemones and then grab them again when its new carapace (outer covering) has hardened. If it then finds itself with just one anemone, it merely breaks it in two, and the anemone obligingly duplicates itself. Surprisingly, the anemones don’t seem to object to being picked up or to being brandished in the face of a predator – at least, one hasn’t been seen trying to escape. And it’s hard to tell what it gets in return other than free travel, but since the boxer uses the anemone to stun food animals, maybe the anemone gets enough leftovers to make life on the claw worth it.

Most explosive defence

NAME | bombardier beetles Carabidae family
LOCATION | on every continent except Antarctica
ABILITY | mixing chemicals to create an explosion

© 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.

Most poisonous animal

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.

Most ingenious tool-maker

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?

Most gruesome partnership

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.

Best electro-detector

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 of an attack. But for hammerheads, it’s the main thing, and it could be one reason why their heads are shaped in the curious way they are.

Sharks have special electrical receptors – hundreds of tiny, dark pores called ‘ampullae of Lorenzini’ – which are filled with a conductive gel that transfers electrical impulses to a nerve end in each pore. Ordinary sharks have these all over the snout and lower jaw, forming a curious pattern of dark holes resembling a sparse five-o’clock shadow.

But hammerheads also have a mass of them across the underside of their oblong heads, which scan across the sandy sea-bottom like metal detectors, searching for prey animals that can’t be found in any other way – creatures such as stingrays and flatfish that bury themselves, lie still and usually have no appreciable scent.

The hammerheads are able to detect the slight direct currents caused by interaction between the bodies of their prey and the seawater and the even slighter alternating currents caused by muscle contractions around an animal’s heart. The eight species of hammerhead can sense it better than most other sharks, and the biggest of these, the great hammerhead, which measures up to 6m (20ft) long, may be able to sense it best of all.

Stickiest skin

NAME | holy-cross, crucifix or Catholic toad Notaden bennetti
LOCATION | Australia
ABILITY | producing a super ‘superglue’

© Ken Griffiths/ANTphoto.com

Some of the world’s strangest creatures are found in Australia – a continent of extremes giving rise to extreme adaptations. The holy-cross toad lives where many other amphibians can’t: in hot, harsh areas inland, where droughts may last for several years. It uses its strong back legs to burrow down in the soil, where it sits out the heat of the day, and when drought sets in, it survives by digging a chamber a metre or so underground in which it aestivates (becomes dormant), emerging only when the rains return.

Like its close toad relatives, the holy-cross also has unique glands in its skin. If it is disturbed or distressed, these release a special secretion that turns into glue. The glue hardens in seconds and has a tensile strength five times that of other natural glues. This is particularly useful should ants attack, as even the biggest immediately get stuck to the toad’s skin. And since, like all frogs and toads, it sheds its skin and eats it about once a week, the holy-cross toad has the pleasure of swallowing the ants that attack it.

Scientists in Australia are now trying to produce an artificial glue as good as the toad’s. Holy-cross toad glue will stick plastic, glass, cardboard and even metal together. More importantly, it can repair splits in cartilage and other body tissues and therefore might prove to be a miracle adhesive that will help surgeons repair the most difficult of injuries.

Deadliest plant

NAME | castor bean Ricinus communis
LOCATION | worldwide; origin unknown, but probably Ethiopia
ABILITY | producing the deadly poison ricin

© Haroldo Palo Jr/NHPA

The castor bean plant produces possibly the most deadly plant toxin, 6,000 times more deadly than cyanide, but it has also been known for thousands of years as a wonder plant. The secret and the poison both lie in the seed. More than 50 per cent of it comprises a rich oil, but to protect it from being eaten is ricin, a protein toxic to almost all animals (lesser quantities of ricin occur in the leaves). The poison, once ingested, inactivates the key protein-making elements of a cell without which it can’t maintain itself and dies.

For humans, death is prolonged, ending in convulsions and failure of the liver and other organs. There is no known antidote. The most usual cause of poisoning comes from accidentally eating seeds, but ricin can be administered in aerosol form, in food or water, or injected, as in the famous case of a dissident Bulgarian journalist. While waiting at a bus stop at Waterloo station in London, in 1978, Georgi Markov was murdered by being stabbed with an umbrella that injected a pellet containing ricin. Widely available and easily produced, ricin could be used for biological warfare.

It is equally easy to extract the seed’s valuable oil, however, which has been used for at least 4,000 years as a lamp oil and soap and also as medicine for a huge array of ailments. Today its uses include high-grade lubricants, textile dyes, printing ink, waxes, polishes, candles and crayons. In the future, its array of protective chemicals may even provide a cure for tumours.

Biggest blood-sucker

NAME | Amazon leech Haementeria ghilianii
LOCATION | Amazon basin
ABILITY | drinking up to four times its weight in blood

© Werner A Wuttke

No, the biggest blood-sucker isn’t a vampire bat. Vampires, which are native to the tropical Americas, don’t actually suck blood – they lap it up. They find large mammals – most noticeably cows, pigs or horses – make a cut in their skin and then drink the blood. Not being very big (average body length is 6.5–9cm/2.5–3.5in), a single bat only actually consumes a few tablespoons of blood a night, though because of the anticoagulant in its saliva, the prey keeps bleeding for some time after the bat has flown away.

The world’s largest leech, measuring up to 46cm (18ins) does suck blood, however, and a very hungry one can take in four times its body weight before it becomes satiated. Since a large Amazon leech weighs about 50g (1.8oz) – the record is 80g (2.8oz) – that’s a lot more than a few teaspoons of blood. Like the vampire, the Amazon leech feeds on large mammals, which it attacks when they enter water, and it also uses an anticoagulant to keep the animal’s blood flowing. But the leech injects an anaesthetic, too, so that the temporary host is unaware of what’s happening to it.

All leeches are segmented worms – their nearest relatives are earthworms – and all, regardless of size, have precisely 32 segments. A few segments at each end of the Amazon leech are modified into suckers for attaching to prey, and every segment has its own independent nerve centre – hence a leech has 32 brains.

Keenest sense of smell

NAME | polyphemus moth Antheraea polyphemus
LOCATION | North America
ABILITY | a male can detect a female on the evidence of just one molecule

© Jeff Lepore/Science Photo Library

Many animals rely on their sense of smell to find food or a mate and even to find their way around. Some live in places where other senses are of little use – eyes don’t help much if you spend most of your life in the dark, and ears would be hopeless in a particularly noisy environment – so they rely on smell more than most.

Some animals, such as sharks, are selective in their smelling abilities and are super-sensitive to significant smells that are relevant to activities such as feeding or breeding. In fact, smell is so important to sharks that they have been dubbed ‘swimming noses’. Their smell receptors are fine-tuned to picking up small concentrations of fish extract, blood and other chemicals – but so are the receptors of many other animals. Some catfish have such super-receptors that they can smell compounds at 1 part to 10 billion parts of water.

The likelihood is, though, that moths are the record-holders, especially the males. They use their antennae to home in on the sex pheromones, or chemical allures, released by females and can even detect if these females are on plants suitable for egg-laying. Some females release deviously small amounts of pheromone, to make sure that only those males with the most highly tuned antennae can follow the trails. The likely record-holder for the best known sense of smell is the polyphemus moth: just one pheromone molecule landing on a male’s antennae will trigger a response in his brain.

Most enthusiastic singer

NAME | humpback whale Megaptera novaeangliae
LOCATION | oceans worldwide
ABILITY | singing the longest and most complex songs in the animal kingdom

© Flip Nicklin/Minden Pictures/FLPA

Drop a hydrophone into the water in an area where humpback whales are breeding and you may hear a baffling medley of moans, groans, roars, snores, squeaks and whistles. These are the hauntingly beautiful sounds made by male humpbacks, which are famous for singing the longest and most complex of animal songs. Since most singing takes place at the breeding grounds, it is probably used to woo females and to warn away rival males – but the songs may also have more subtle meanings and nuances that we do not yet understand.

A song can last for as long as half an hour, and as soon as the whale has finished, it often goes back to the beginning and sings it all over again. Each song consists of several main components, or phrases, which are always sung in the same order and repeated a number of times, but are forever being refined and improved. All the humpbacks in one area sing broadly the same song, incorporating each other’s improvisations as they go along. This means that the song heard one day is different from the one being heard several months later and, in this way, the entire composition changes over a period of several years.

Meanwhile, humpback whales in other oceans sing very different compositions. They probably all croon about the same trials and tribulations in life, but the differences are so distinctive that experts can tell where a whale was recorded simply by listening to the intricacies of its own special song.

Most gruesome tongue

NAME | isopod Cymothoa exigua
SIZE | up to 4 cm long
ABILITY | eating and then mimicking the tongue of the spotted rose snapper fish

© Matthew Gilligan

This is probably the world’s most specialised and gruesome isopod – one of a group of crustaceans including woodlice, marine gribbles and slaters. Most isopods lead perfectly normal lives as herbivores, scavengers or carnivores, but some are parasites. Cymothoa exigua has a tendancy to select the mouth of the spotted rose snapper fish for its hangout.

Latching on to the fish’s tongue with its hooked legs (pereopods), it feeds on mucus, blood and tissue, gradually eating away the tongue. Gripping onto the tongue stub, the isopod then effectively becomes the fish’s tongue, growing as its host grows and feeding on particles of meat that float free as the fish eats. The biggest individual isopod recorded was 39mm (1.5in), but presumably it can grow to be as big as the fish needs its tongue to be.

Perhaps the practice is not as gruesome as it looks, as the rose snapper can continue to feed, but no one knows whether a time comes when Cymothoa decides to let go and get a taste of blood in someone else’s mouth. Strangely, the relationship between the fish and its parasite has been observed only in the Gulf of California, or Sea of Cortez, though the fish is found in the eastern Pacific, from Mexico to Peru. It is the only known example of a parasite replacing not just a host’s organ but also its function (to hold prey) – a hard act to swallow.

Most inquisitive bird

NAME | kea Nestor notabilis
LOCATION | New Zealand
ABILITY | curiosity

© Tui De Roy/Minden Pictures/FLPA

Parrots are highly inquisitive, but even among parrots, keas are exceptional. They’re native to New Zealand’s South Island, a cold, snowy, unparrotlike place where keas have to use all their wits to find a meal. While parrots elsewhere are flying from one conspicuous fruit to another, keas are searching under rocks and bark and in bushes, cones and shells for food such as roots, shoots, berries or insect larvae. This and a mountainous habitat virtually free of predators has, over 2.5 million years of evolution, made them insatiably curious. And they’re especially drawn to things they’ve never seen before. So when humans arrived in New Zealand, the keas were delivered a bonanza of new objects to investigate for food.

Nowadays great sources of fascination are camping grounds and ski-resorts. These parrots are large and have powerful beaks, and they can rip right through a canvas tent for the sheer joy of investigation. A particular favourite is the rubber on cars – windscreen wipers mainly. One gang of keas is said to have ripped out the rubber lining around the windscreen of a tourists’ hire car, causing the glass to fall inwards and opening up the interior. When the tourists returned, they found clothes, food and car parts scattered in the snow, while the keas appeared to be playing a game of football with an empty Coke can. The birds then retreated and watched – with great curiosity, it seemed – to see what the tourists would do about it.

Biggest drug-user

NAME | chimpanzee Pan troglodytes
LOCATION | forests in East, West and Central Africa
ABILITY | self-medication

© Steve Robinson/NHPA

Yes, humans are the biggest drug-users. But we are not the only ones who use drugs, and we are only just beginning to discover the pharmaceutical knowledge of other animals. The current top-of-the-list user is the chimpanzee. Like us, chimps get stomach ache from time to time after overeating or consuming toxins. They also get parasites and diseases, and stressed animals usually end up feeling pretty ill.

It’s not surprising that an intelligent primate such as a chimp, which learns by trial and error and example, should have started to use medicinal products, since their forest habitat is full of them. In Tanzania, chimps suffering from diarrhoea have been seen using the leaves of the ‘bitter leaf’ tree that local people know as a medicine for malaria, amoebic dysentery and intestinal worms. Across Africa, chimps have been seen seeking out rough-leafed plants, plucking whole leaves from them, carefully folding the leaves, rolling them around in their mouths and then swallowing them. Excreted whole, the leaves push out parasites such as intestinal worms.

Many other animals also appear to self-medicate. Capuchin monkeys have been seen rubbing their fur with pungent plants that contain healing and insect-repellant properties. Black lemurs rub insect-killing chemicals from millipedes onto their fur. An elephant has been observed seeking out labour-inducing leaves of a tree just before giving birth. Given our increasing need for new antibiotics and remedies, such examples provide a good reason to keep nature’s pharmacy intact by respecting the environment.

Most painful stinger

NAME | box jellyfish Chironex fleckeri
LOCATION | near-shore waters of parts of Australia and South-east Asia
ABILITY | causing excruciating pain and possible death

© Valerie & Ron Taylor/ardea.com

Some say this is the world’s most venomous animal, but this depends what you mean. Is it the venomous creature you are most likely to encounter, does it kill more people than any other, or are the chemicals most toxic? Certainly, a single box jellyfish contains enough venom to kill at least 60 people, and many do die after being stung.

Though the jellyfish has no desire to kill humans, it is a hunter. An adult box jellyfish – as large as a human head, with tentacles up to 4.6m (15ft) long – has a full array of powerful stinging cells, called nematocysts, and hunts mainly fish. It is very active (unlike many other jellyfish) and jet-propels itself through the sea in search of prey. It’s also transparent, ensuring that fish (and humans) don’t spot its deadly tentacles.

There are four bundles of about ten tentacles, most over 2m (6ft 6in) long and each carrying around 3 million nematocysts. The toxin contains chemicals that affect heart muscle and nerves and destroy tissue, the purpose being to kill a fish quickly so it doesn’t get away. But if a box jellyfish encounters a human, it may also sting in self-defence. The pain is excruciating, and without anti-venom, a victim can die from heart failure in just a few minutes. In addition, nematocysts fire not just on command but when stimulated physically or chemically. Strangely, they can’t penetrate women’s tights, and until ‘stinger suits’ became available, lifesavers patrolling beaches would wear tights unashamedly.

Slipperiest plant

NAME | pitcher plants Nepenthes species
LOCATION | South-east Asia
ABILITY | catching prey in slippery, deadly pitchers

© Mark Moffett/Minden Pictures/FLPA

There are many different species of pitcher plant, but all are insect-traps with the slipperiest of sides, providing extra nitrogen (from insect corpses) to help the plants flower and set seed. Among the most sophisticated are the leaves of vine-like Nepenthes. Each of these pitfall traps has an ‘umbrella’ lid and a base partly filled with a soup of digestive enzymes. The lure may be colour (usually red), smell (nectar or, later, rotting corpses) or tasty hairs. When an insect lands on the rim, it slips into the deadly broth, possibly intoxicated by narcotic nectar.

Slipperiness is achieved in two ways, perhaps depending on what insects are likely to be attracted (walking insects if the Nepenthes is on the ground or flying insects if it is up in the tree canopy). The inner walls are usually impossible to climb, being covered with slippery waxy platelets. Others go a stage further and have a surface that attracts a film of water which aquaplanes the insects to their death. Some also use trickery. When their pitchers are dry, ants are lured by the nectar, and don’t slip, and so go and tell more ants about the find. If the surface is wet when they return, they all fall in.

Another of the Nepenthes species is in partnership with an ant that has specialised feet, allowing it to get in and out of the pitcher to retrieve corpses. It eats these and drops the remains and its faeces into the pitcher, so speeding up the release of nitrogen for its predatory host to ingest.

Heaviest drinker

NAME | broad-tailed hummingbird Selasphorus platycercus
LOCATION | North America
ABILITY | can drink up to five times its body weight in a day

© Mary Plage/Oxford Scientific Films

To say this or any other hummingbird drinks like a fish is to understate how much it drinks. In proportion to its body weight, it drinks a lot more than a fish. (Just to get that cliché straight: freshwater fish don’t drink – they absorb water through their skin. Saltwater fish that drink don’t do so to excess.) In the case of the hummingbird, it’s the fault of the flowers. Hummingbirds have evolved to drink nectar. The flowers they visit have evolved to provide that nectar, and the nectar they provide is typically about 30 per cent sugar and the rest water. To keep their wings going at a rate quicker than the human eye can see – to hover – hummingbirds need a huge amount of sugar, which means that by drinking nectar they take in up to five times their body weight in water every day.

If any other animal, including a human, tried to drink even one times its body weight, it would be dead long before it could do it. So while hummingbirds were evolving beaks to fit into the flowers with their watered-down nectar, they were also having to evolve nature’s heaviest-duty kidneys. Some water just passes through the bird unprocessed, but 80 per cent goes to the kidneys to be expelled as very dilute urine. And why the broad-tailed in particular? It’s simply the most energetic hummingbird, and thus the most supersaturated.

Best mimic

NAME | Indo-Malayan mimic octopus
LOCATION | Indonesian-Malaysian archipelago
ABILITY | pretending to be anything but an octopus

© Roger Steene/imagequest3d.com

If you are a medium-sized predator, the average octopus is one of the most edible animals in the sea. It’s substantial and meaty, and without a shell, bones, spines, poisons or any other unpleasant defence mechanisms. In fact, the best defence most species of octopus have is to stay hidden as much as possible and do their own hunting at night.

So to find one in full view in the shallows in daylight was a surprise for two Australian underwater photographers, swimming off the Indonesian island of Flores in the early 1990s. Actually, what they saw at first was a flounder. It was only when they looked again that they saw a medium-sized octopus, with all eight of its arms folded and its two eyes staring upwards to create the illusion of a fishy body. An octopus has a big brain, excellent eyesight and the ability to change colour and pattern, and this one was using these assets to turn itself into a completely different creature.

Many more of this species have been found since then, and there are now photographs of octopuses that could be said to be morphing into sea snakes (six arms down a hole, and two undulating menacingly), hermit crabs, stingrays, crinoids, holothurians, snake eels, brittlestars, ghost crabs, mantis shrimp, blennies, jawfish, jellyfish, lionfish and sand anemones. And while they mimic, they hunt – producing the spectacle of, say, a flounder suddenly developing an octopodian arm, sticking it down a hole and grabbing whatever’s hiding there.

Most formidable killer

NAME | killer whale, or orca, Orcinus orca
LOCATION | oceans worldwide
ABILITY | preying on the world’s largest animals

© Mark Carwardine

Anything that can attack and kill the largest animal that ever lived, the blue whale (see), has to be the greatest predator ever (apart, of course, from Homo sapiens). But blue whales are peaceable creatures with few defences apart from size, and so maybe the killer whale qualifies better on the grounds that it can kill the great white shark. At a maximum length of 9m (29ft 6in), killer whales are the largest members of the dolphin family and among the largest of all predators, but their real edge is that they’re pack hunters and work together to subdue large prey.

Several distinct forms are known – residents, transients and offshores – each of which differ significantly in appearance, behaviour, group size and diet. The transients are the ones that tend to specialise in larger prey but, perhaps surprisingly, they travel in smaller groups than their fish-eating relatives: fewer than six or seven is fairly typical (fish-eating groups often comprise 15–30 whales). The transients devise different, often ingenious, hunting techniques for different prey. In the Antarctic, for example, they will tip seals and penguins off ice floes and into the mouths of their group-mates; and in Patagonia, they beach themselves to grab sealion pups.

When Basque whalers saw killer whales feeding on the carcasses of dead whales, they called them ‘whale killers’, and the name stuck. Many people prefer to use the more politically correct name, orca, but in Latin, orcus means ‘belonging to the kingdom of the dead’, and so it’s not much better.

Best architect

NAME | African termite Macrotermes bellicosus
LOCATION | sub-Saharan Africa
ABILITY | creating an air-conditioned, multi-storey communal residence

© John Shaw/NHPA

Some 200 species of ant – most famously leafcutter ants – farm fungus inside their nests as a source of fast food. So do about 3,500 beetles and 330 species of termite. But of all these insects, none seems to cultivate a more difficult crop than the African termite, and no crop requires more elaborate technology to maintain it. The staple fungus of African termites grows only on their faeces and needs a very particular temperature. Anything above or below 30.1°C (86°F) is too hot or too cold, and every aspect of the construction of the termite mound is part of an effort to keep the temperature exactly that.

The termites always build with mud, above a damp pit. They dig at least two long boreholes down to the water table. They also construct a 3m (10ft) diameter cellar, about 1m (3.3ft) deep, with a thick central pillar that supports the main part of the mound. This houses the queen, the nursery and the fungus farms. On the ceiling of the cellar are thin, circular condensation veins, and around the sides of the mound are ventilation ducts. On top are hollow towers – chimneys – that rise 6m (20ft) above ground level. Every dimension is just right for the precise circulation of air and moisture that will keep the fungus at 30.1°C no matter what it’s like outside. What’s more, workers are only a maximum of 2cm (0.8in) in size, and so in relative terms, the mound is taller than any human building – the equivalent of 180 storeys.

Most painful tree

NAME | gympie-gympie stinging tree Dendrocnide moroides
LOCATION | Australia
ABILITY | defending itself with toxic chemicals

© Bill Bachman/ANTphoto.com

Of course, any tree could fall on you, and plenty of trees are poisonous to eat, but this aside, the trees that cause the most excruciating pain are ones that you just brush against. These are the stinging trees that are found in several parts of the world but are most persistently painful in that land of advanced toxins, Australia. Here are six Dendrocnide species, two of which – the northern shiny-leaf stinging tree and the southern giant stinging tree – are large, tree-like trees, and four of which are more like shrubs. Of the six, the worst agony is said to be inflicted by a shrub, the gympie-gympie, but they all hurt a lot.

What looks at first like a layer of fur on all parts except the roots is really a mass of tiny glass (silicon) fibres containing toxic chemicals. Just a brush against a tree results in the skin being impaled with a scattering of fibres, which act like hypodermic needles and are all but impossible to extract (Australian first-aid kits sometimes include wax hair-removal strips). The poison causes burning, itching, swelling and sometimes blistering that is said to be at its most unbearable soon after contact but can keep causing pain for years. The fibres can penetrate most clothing, and sometimes air-borne ones can be inhaled. Oddly, the stings don’t affect all animals. Insects and even some native mammals actually eat the leaves. The ones that suffer tend to be introductions to Australia, such as dogs, horses and humans.

Loudest bird call

NAME | kakapo Strigops habroptilus
LOCATION | New Zealand
ABILITY | producing a boom that can be heard up to 5km (3 miles) away

© ANT Photo Library/NHPA

Which bird is loudest depends on who is listening and where. The song of a nightingale overcoming traffic noise is so loud (90 decibels) that prolonged exposure to it could, theoretically, damage your ears. So could the even louder, shrill, 115-decibel cry of a male kiwi or the metallic ‘bonks’ of the Central American bellbird, designed to carry in thick rainforest. But possibly the best long-distance sound to make is a boom.

In Europe, the booming record-holder is the bittern. But the world record-holder is probably the New Zealand kakapo, which is now extinct on the two main islands and, despite great conservation efforts, numbers fewer than 90 individuals. Every three or four years, the normally solitary males gather at traditional kakapo amphitheatres – display grounds with excavated bowls. Here they puff up air sacs in their chest and belly and start booming, an average of 1,000 times an hour for 6–7 hours a night (kakapos are nocturnal, and sound carries best in the colder night air). They do this for 3–4 months to call in likely mates to witness their dance displays and for mating. But since this giant, flightless parrot is now confined to a handful of offshore islands, few people will ever hear its eerie, ‘fog-horn’ boom.

Intriguingly, the booms of Australasian cassowaries are nearly as loud but have an added long-distance element: a low-frequency component below the range of our hearing (though it can be felt). It’s likely that a kakapo boom also contains ultra-low-frequency sound, but its booming is now so rare that it has yet to be completely analysed.

Deadliest drooler

NAME | Komodo dragon Varanus komodoensis
LOCATION | islands of Komodo, Rinca, Gili Motang, Gili Dasami and Flores, Indonesia
ABILITY | producing dangerous bacteria-laden saliva

© Mark Carwardine

The Komodo dragon is a renowned giant: the average male is more than 2.2m (7ft 5in) long, and some measure up to 3.1m (10ft 2in). The longest lizard of all, however, is its much slimmer relative, the Salvadori monitor from New Guinea, though two thirds of its 2.7m (8ft 8in) maximum length is made up by its tail.

But the Komodo dragon is the heaviest lizard of all, with an average weight of 60kg (130lb) and a maximum of 80kg (176lb), and it is a fearsome predator. It has large, sharp, serrated teeth for cutting and tearing prey, but its hidden weapon is its bacteria-laden saliva. Once bitten, a victim may escape, but within a few days it will succumb to infection. The dragon then tracks it down with its acute sense of smell – a sense that also makes it a super-efficient scavenger.

Though it is a giant by today’s standards, the Komodo dragon may be a pygmy compared to one of its mainland ancestors (Flores Island supported other ‘pygmies’, including a now-extinct elephant, on which the dragon is believed to have preyed). In Australia there once existed a true giant, the 6.9m (23ft), 617kg (1,370lb) monster monitor Megalania prisca, which became extinct about 40,000 years ago. The Komodo dragon poses relatively little threat to humans and usually only bites when cornered. But Megalania, whether or not it was a deadly drooler, would have been a lizard to be very, very afraid of.

Most sensitive slasher

NAME | sawfish Pristis species
LOCATION | shallow, warm coastal waters
ABILITY | using its saw for slashing and sifting

© Marty Snyderman/imagequest3d.com

A sawfish has external teeth, set around a sensitive, flat snout – the saw, or rostrum (here shown from the underside). Swung from side to side, the saw can be used as a powerful weapon to slash shoaling fish such as mullet and herring, which it then eats off the sea-bottom. Generally speaking, though, the sawfish is a slow and peaceable animal, spending its time in shallow, muddy water, raking the mud with its saw for crustaceans and other prey. The saw-teeth get worn by all this grubbing, but they grow continuously from their bases and so don’t wear out.

Like its close relatives, the rays, it’s perfectly camouflaged against the bottom of the sea, and like its more distant relatives, the sharks, it swims in an undulating way. And like both groups, its hard bits are cartilage, not bone, and its teeth are adapted scales. It has another similarity. Using special cells, the ‘ampullae of Lorenzini’, on its saw and head, it can detect electrical fields generated by prey.

One problem for females is that they give birth to live saw-babies. But a youngster’s saw is covered with a sheath to make birth relatively painless. A much greater problem for all sawfish (possibly seven species) is the fact that their coastal waters are being polluted and developed and that they have been overfished to the point where all are endangered, some critically. A sawfish’s saw is also its downfall. Not only has it been sought after as a trophy, but it also fatally entangles the fish in nets.

Smelliest plant

NAME | titan arum, corpse flower, or devil’s tongue, Amorphophallus titanum
LOCATION | western Sumatra, Indonesia
ABILITY | pumping out the smell of decomposing flesh

© Neil Lucas/naturepl.com

What smells bad to us often doesn’t bother other animals. In fact, the scent of the foul-smelling titan arum – the tallest and probably heaviest of flowering structures – is positively attractive to carrion beetles and bees. Whether its smell is the worst, to us, has still to be tested (there are other contenders for this, including the even bigger giant titan, A. gigas). But the titan arum produces a sufficiently awful smell to make people faint.

The ‘flower’, or inflorescence, comprises a vase-shaped spathe (petal-like leaf) at least 1.2m (4ft) tall, which grows rapidly from a gigantic tuber weighing up to 80kg (177lb). Out of this rises a spadix, a spike with thousands of tiny flowers more than 2.4m (8ft) tall, so strange it gives the arum its scientific name: ‘huge deformed penis’. The upper part of the spike produces the smell, and to make it travel further, the spadix generates heat and may steam at night as it pulses its fragrance of ammonia, rotting flesh and bad eggs for up to eight hours at a time.

This attracts pollinating, carrion-loving insects, but few people have observed the pollination, probably because the plant flowers only every 3–10 years and then for just two days. Once the flower dies and hornbills have dispersed its seeds, it’s replaced by a titanic leaf up to 6m (20ft) tall, which makes the food so that, one day, the tuber can grow another stinking flower.

Most impressive comeback

NAME | Chatham Island black robin Petroica traversi
LOCATION | Chatham Islands, east of South Island, New Zealand
ACHIEVEMENT | increasing in numbers from just five to 250 in 18 years

© Don Merton

New Zealand’s Chatham Islands are believed to have been the last Pacific archipelago to be visited by humans. Yet when people finally did visit, they stayed, and they did a pretty thorough job of doing what humans have always done to islands: stripped them of a lot of their native plants and animals. The Polynesians arrived around 700 years ago, the Europeans came along in the 1790s, and between them they caused the extinction of 26 of the islands’ 68 species and subspecies of birds. The main cause was introduced land mammals, and among the sufferers from cats and rats in particular was the 15cm (6in) endemic black robin.

By 1900 it had disappeared from the two main islands and survived only on Little Mangere, a tiny, windswept stack with sheer cliffs that helped keep predators away but didn’t offer the birds much protection from the elements. By 1972 only 18 were left. By 1976, seven.

In the meantime, though, the government had bought nearby Mangere Island and begun to reforest it, and all the birds were moved there. Nevertheless, by 1980, there were just five, with only one breeding pair. But by fostering eggs to other bird species on other islands – which improved the survival chances of the chicks and spurred the breeding female to nest again – conservationists painstakingly cranked the species back to life. Now there are about 250 black robins on Mangere and South East islands, and there are plans to repopulate other islands in the Chathams.

Hottest animal

NAME | Pompeii worm Alvinella pompejana
LOCATION | deep-sea hydrothermal vents
ABILITY | withstanding scalding water

© Peter Batson/imagequest3d.com

The Pompeii worm thrives in large colonies in one of the darkest, deepest, most hellish places on Earth – close to a geyser of water so hot it could melt the worm in a second. It is also subject to a pressure great enough to crush a person and doused in a soup of toxic sulphur and heavy metals. Communities of Pompeii worms cling to the sides of ‘smokers’ 2–3 km (1.2–1.9 miles) under the sea. These belching chimneys grow over hydrothermal vents on volcanic mountain ranges, created from the chemicals that precipitate out as 300°C (572°F) vent water meets cold seawater.

To survive on a smoker requires super-worm strategies. For its home, the worm makes a paper-like chemical-and-heat-resistant tube. For a thermal blanket, it ‘grows’ a fleece of filamentous bacteria, feeding it with sugar-rich mucus secreted from its back. This blanket may also detoxify the vent fluid in its tube.

Unlike the vent tubeworm Riftia pachyptila, the Pompeii worm has a gut and ‘lips’ which it extends to ‘graze’ on bacteria that grow on the surface of the colony. But no one knows quite how it copes with what are the highest temperatures and temperature gradients experienced by any organism apart from bacteria, for though it angles its head (gills, mainly) away from the hottest water, its tail experiences flushes hotter than 80°C (176°F). Keen to make use of the Pompeii worm’s technology for human endeavours, scientists are now racing against each other to unravel its survival secrets.

Most shocking animal

NAME | electric eel Electrophorus electricus
LOCATION | South American rivers
ABILITY | stunning prey with electrical discharges

© Andrea Florence/ardea.com

Think of it as a living battery. The electric eel can grow to be more than 2m (6ft 5in) long, but its organs are packed just behind its head, leaving 80 per cent of its body to electricity generation. It’s stacked with up to 6,000 specially adapted muscle cells, or electrocytes, aligned like cells in a battery. Each electrocyte emits low-voltage impulses that together can add up to 600 volts – enough to render a human unconscious. The positive pole is behind the eel’s head, and the negative pole is at the tip of its tail. It tends to remain straight when swimming, using its long ventral fin for propulsion, and so keeps a uniform electric field around itself.

Electricity affects almost every bit of the eel’s behaviour. As well as stunning or killing with high-voltage pulses, it communicates with other eels electrically and uses electrolocation (a sort of electrical bounce-back system) to detect objects and other creatures in the water. Fish and frogs are its staple prey, and it can detect the minute electric currents these and other living things produce. The eel can’t see well, but this doesn’t matter much, since it is mainly nocturnal and tends to live in murky water.

There are other electrified fish, including the related knifefishes, which generate a weak electric field around themselves that they use to sense objects and fish prey and to communicate. The only other shockers are the torpedo ray and the electric catfish, but neither is as shocking as the electric eel.

Coldest animal

NAME | wood frog Rana sylvatica
LOCATION | Canada and Alaska
ABILITY | withstanding being frozen for weeks

© J M Storey/Carleton University

There’s an African midge so well adapted to drought conditions that, as a sideline, it can withstand being artificially frozen to –270°C (–454°F). Lots of other insects can survive freezing, too, but the creatures that can withstand cold for the longest period are probably bacteria in Antarctica.

The most freeze-tolerant higher animal is the wood frog, which can literally become a ‘frog-sicle’, enabling it to live further north than any other amphibian and to hibernate close to snowmelt ponds, presumably to give it a head start and enable it to reproduce quickly before the ponds dry.

When the temperature drops below freezing, the frog’s liver starts converting glycogen to glucose, which acts as an antifreeze. The blood passes the glucose to the vital cells, which are then protected from freezing on the inside, all the way down to –8°C (18°F). But the rest of the frog’s body fluids, up to 65 per cent of them, turn to ice and the organs, deprived of blood, actually stop working. Even the eyeballs and the brain freeze. It is effectively the living dead. (The painted turtle Chrysemys picta can do this, too, but only briefly.) When a thaw comes, the frog’s heart starts beating and pumps blood containing clotting proteins around the body, which stops bleeding from wounds caused by the jagged ice crystals. The frogsicle quickly comes back to life and, just as miraculously, so do the frozen parasitic worms in its body.

Most talkative animal

NAME | African grey parrot Psittacus erithacus
LOCATION | Central and West Africa
ABILITY | communicating with humans

© Jenny Pegg

African greys live in huge flocks that sweep through the rainforests foraging for fruit, nuts, seeds and herbs and constantly communicating with each other. In the wild, no one has been able to do more than categorise their calls as, for example, threat or making contact. These calls could, though, be far more meaningful and complex if the language skills of pet grey parrots are anything to go by – for African greys can be taught to understand and speak human language and may some day even be able to read words.

The most famous of these parrots (though several others have been making the news recently) is Alex, protégé of Dr Irene Pepperberg of Brandeis University in Massachusetts. Alex can identify the colours and shapes of objects and what they’re made of. He can, for instance, say, ‘four-corner wood square’ if that’s what he’s been shown. If he wants to be given something or to go somewhere, he only needs to ask. And he can actually make wisecracks and some rudimentary conversation.

One story Dr Pepperberg tells about him is how during a demonstration of his ability to identify alphabetic letters on cards, Alex would say ‘sssss’ for S, ‘shhh’ for SH, ‘tuh’ for T and so on and after each correct answer would ask for a nut. Since that would have slowed things down too much, Dr Pepperberg would say each time, ‘Good birdie, but later.’ Finally Alex looked at her, narrowed his eyes and said, ‘Want a nut. Nnn, uh, tuh.’

Most bizarre defence

NAME | Texas horned lizard Phrynosoma cornutum
LOCATION | southern USA and Mexico
ABILITY | blood squirting

© Raymond Mendez/Oxford Scientific Films

Revered by native peoples for thousands of years, the Texas horned lizard has an array of abilities. It eats mainly ants – and lots of them, since much of an ant is indigestible. This necessitates a huge stomach. Eating more than 200 ants a day means exposure in the open for long periods, and being stomach-heavy means a horned lizard finds it difficult to scamper away from predators.

Instead, it relies on an armoury of defences. It has camouflage colouring, with an outline broken by spines and outgrowths, and it will freeze if a predator approaches. Its horns and spines can pierce the throat of a snake or bird, and it can hiss and blow itself up to look even more fearsome. When it comes to coyotes, foxes and dogs, a horned lizard’s most spectacular defence is to squirt foul-tasting blood from sinuses behind its eyes. That usually has the desired effect. But it squirts only when it’s provoked, since it risks losing up to a quarter of its blood.

Such abilities are, however, no defence against human invasion of its land. Its strange shape and colouring has made it attractive to reptile collectors, and its habit of freezing means it is prone to being run over. And with humans have come exotic fire ants, which it can’t eat and which are replacing the native ants on which the lizard depends – a sorry way for such a determined survivor to go.

Smelliest animal

NAME | striped skunk Mephitis mephitis
LOCATION | North America
ABILITY | defending itself with a spray containing the smells that mammals hate most

© T Kitchin/V Hurst/NHPA

Bad smell is all in the nose of the receiver, and we humans have far fewer sensors than most animals. Nonetheless, we can smell a striped skunk up to 3.2km (2 miles) away, if the wind is in the right direction. It’s possible to train our brains to ignore the most disgusting of smells, from vomit and faeces to rotting flesh – but never skunk. Other animals, including African zorillos, Tasmanian devils, wolverines and different species of skunk, produce revolting musk when threatened or attacked, but not of the strength or permanence of striped skunk spray.

The amber oil is made in two muscular glands under the skunk’s tail and can be delivered as a spray or precision jet up to a distance of 3.6m (12ft). The spray contains compounds which are the cause of the vomit-producing smell, like very, very rotten eggs. It can also cause temporary blindness and, if swallowed, unconsciousness. It is virtually impossible to remove from clothes, which are best thrown away after a close encounter.

Other mammals are also revolted by it, and so the skunk’s only serious predator is the great horned owl, which probably has little need of a sense of smell. Skunks prefer not to waste their musk, as the glands take a couple of days to refill, and so they usually raise their black-and-white tail as a warning before spraying. But such warnings go unheeded on roads, which is why cars are now their worst enemy.

Slimiest animal

NAME | hagfish Myxini species
LOCATION | worldwide
ABILITY | drenching predators in mucus by the bucketful

© Peter Batson/imagequest3d.com

This is an eel-like animal, 0.5–1m long (20–33 in), without fins, jaws, scales, a backbone or much in the way of eyes. Though not a true fish, it does have gills and excels in a fish-like trait – producing slime. For fish, a thin slime coating is a way of regulating the salt and gas balance between their bodies and the water, repelling parasites and maintaining speed. But for a hagfish, slime is also a weapon.

Its lifestyle is pretty basic, even a little squalid: it lives on the sea-bottom, usually at around 1,200m (4,000ft), where it eats anything it can overcome or scavenge. When it finds a suitable victim, it slithers into it, usually by way of its mouth, and then uses its toothed tongue to rip the animal to pieces from the inside out.

That’s nothing, however, compared to what it does when it’s threatened. Glands all along its sides exude a slime concentrate that reacts with seawater to create a cloud of mucus goo hundreds of times larger than the original secretions. It’s very tough goo, too – reinforced by thousands of long, thin, strong fibres – and the offending predator or unlucky passer-by becomes stuck in it and suffocates. The hagfish itself would suffer a similar fate, except that it has a way of extricating itself: it ties itself into a knot and slips the knot down the length of its body, squeezing free in the process.

Keenest hearing

NAME | greater horseshoe bat Rhinolophus ferrumequinum
LOCATION | Europe and Morocco east to Afghanistan and Japan
ABILITY | tracking and catching insects at speed in total darkness

© David Hosking/FLPA

To hunt and orient oneself in the dark requires an extreme sense. Bats do it by ‘seeing’ with echolocation. They emit high-frequency (ultrasound) pulses from their mouths or noses and analyse the returning echoes to determine the size, shape, texture, location and movements of the smallest of objects. A bat’s nose structure helps focus the sound, and its complex ear folds catch the returning echoes. Echoes from above hit the folds at different points to those from below. And by moving its ears, a bat can hear sound bouncing back from different angles.

The noise is so intense that, to avoid going deaf, most bats ‘shut off’ the sound in their ears as they signal. A bat may ‘shout’ – at 110 decibels, in the case of the little brown bat, which hunts in open spaces; or it may ‘whisper’ at 60 decibels, in the case of the northern long-eared bat, which catches insects around vegetation. Bats using lower frequencies (longer wavelengths), such as the greater horseshoe, tend to glean insects off vegetation or hunt large ones; those using higher frequencies (shorter wavelengths) generally catch flying insects at closer range.

While it is difficult to be certain that the greater horseshoe bat has better hearing than other bats, its echolocation system is one of the few studied in detail and it is undoubtedly impressive. But many other bats have incredibly keen hearing, too, and it is possible that the real record-holder has yet to be discovered.

Stickiest spitter

NAME | spitting spider Scytodes species
LOCATION | worldwide
ABILITY | snaring and immobilising prey with sticky spit

© Robert Suter

The spitting spiders are most closely related to the venomous brown recluse spiders. Like the brown recluses, they have only six eyes (as opposed to eight) and relatively poor vision. But they make up for it with their snaring skills. Their main sense is touch and, as the spiders walk, their two front legs, which are longer than the other six, tap the ground ahead, feeling for something edible.

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