The Book of Animal Ignorance (8 page)

Catfish

Swimming tongue

T
here are over 2,200 species of catfish and they are found on every continent except Antarctica. They live in the frozen rivers of Siberia and the steamy swamps of Borneo. Species have been found in the Himalayas and the Andes at altitudes of over 14,000 feet, while others bask in the warm coral reefs of the South Pacific. They range in size from some of the smallest known fishes to the largest.
Scoloplax dicra
is fully grown at half an inch while the European wels (
Silurus glanis
) grows to 16 feet and can weigh 650 lb.

Catfish account for about 8 per cent of all fish and are among the most remarkable creatures on earth. There is a talking catfish, a walking catfish, an electric catfish, an upside-down catfish and a catfish that looks like a banjo, but what really makes them stand out is their senses – the most finely tuned in nature. They have more taste buds than any other creature. Their entire bodies are covered with them. A 6-inch catfish may have over a quarter of a million taste buds, not just in its mouth and gills, but on its whiskers, fins, back, belly, sides and tail. The channel catfish has the best sense of taste of any vertebrate, able to detect less than a hundredth of a teaspoonful of a substance in an Olympic swimming pool full of water.

Catfish also have extraordinary senses of smell, touch and hearing. They can smell some compounds at a dilution of 1 part in 10 billion. They have no visible external ears, but because they are the same density as water, their whole body acts as a giant ear. In addition, ultra-low-frequency sound is picked
up by the lateral line, small pores along the fish's side containing tiny hair-like projections that are supersensitive to vibrations. These are used to find prey and avoid predators. The Chinese have exploited this talent for centuries, using catfish to warn of earthquakes: they are said to be able to detect them days in advance.

Catfish do not have scales – their smooth skin gives them a heightened sense of touch – and some also have excellent eyesight, especially the channel catfish (
Ictalurus punctatus
, Latin for ‘spotted fish-cat') whose eyes are used for medical research into vision. Other parts are used to study herpes, their gonads are removed for research into reproduction and, if that were not enough, this unfortunate creature (variously known as the willow cat, forked-tail cat, spotted cat or lady cat) is also delicious. It ranks third after bass and crappie as the most popular fish to catch in Texas. As well as all the familiar senses, catfish – like sharks – have an extra one called electroreception that detects the electrical fields of worms and larvae buried in mud. Most catfish are harmless to humans (though some can give you a nasty jab with their toxic spines) but beware the
candiru
, a tiny catfish that lives in the Amazon. If you swim in its murky waters and urinate, the fish will find its way into your urethra. Once inside, it erects its spines, causing inflammation, haemorrhage and death.

THE MOUTHBROOD DIET

Cheetah

The savannah strangler

C
heetahs used to range across the whole of Africa and most of southern Asia. Over the past century, their population has shrunk dramatically as a result of hunting for fur and to protect livestock. Of the 12,000 surviving animals, only a hundred survive in Asia, in a tiny wildlife park in the Iranian mountains.

Cheetahs have almost disappeared before. The modern population can be traced back to a single African group of 500 animals that survived the last ice age. Genetically, this means all living cheetahs are as close as identical twins.

Cheetahs are fast because they have to be: unlike most big cats, they hunt during the day, climbing termite mounds to spot stray antelope or gazelle. The black ‘tears' under their eyes are thought to cut down glare and they have a wide, super-sensitive stripe on their retinas that gives sharp focus across the entire width of their vision, allowing them to chase and turn with near perfect accuracy. Anything within a 2-mile radius is in trouble.

Only a handful of cars can reach 60 mph faster than a cheetah and none can do it on grass. But they have to be quick. Unless the antelope is caught within thirty seconds, the cheetah will overheat. They kill by strangulation. Their teeth aren't as long or as sharp as a lion's or a leopard's but their bite is more powerful, crushing the windpipe and blocking the airflow. If successful, it then has to bolt its food, leaving behind the skin, bones and intestines. An adult can take on board up to 30 lb of flesh in a sitting (equivalent to an adult human polishing off six legs of lamb) and survive on it for five days. Lions, vultures and hyenas steal half of all kills but cheetahs don't argue.

BUILT TO SPRINT

They know a single injury to their ‘fit-for-purpose' body will doom them to starvation.

A female cheetah will sometimes bring back a live antelope calf to train her offspring. Cubs start hunting at eighteen months and, untrained, will often chase after completely inappropriate prey like buffalo.

‘Cheetah' is originally a Hindi word,
chita
, which comes from the Sanskrit,
chitraka
, meaning ‘speckled'. There was confusion for a long time between cheetahs and leopards. When a medieval writer uses ‘leopard' he usually means a cheetah. They were believed to be the illegitimate offspring of lions (which have manes) and ‘pards' (which were spotted). Cheetah cubs do have manes (it helps camouflage them in grass). Their Latin name,
Acinonyx
jubatus
, means ‘fixed-claw with a mane'.

In ancient Egypt, India and Persia, cheetahs were trained to hunt by humans. Rewarded with butter and taught to recognise fifteen vocal commands, they were taken out on horseback, wearing hoods like falcons, and then set after antelope.

They are notoriously difficult to breed in captivity because the female needs to be chased by several males before she can ovulate. The sixteenth-century Mughal emperor, Akbar the Great, kept over a thousand cheetahs but managed only one litter. The next cheetah born in captivity wasn't until 1956.

Chimpanzee

The thinking man's ape

I
t is almost impossible to discuss the history of our nearest living animal relative without talking about ourselves. In 2002, a series of British TV adverts featuring chimpanzees dressed as a family of humans ended after forty-six years – the longest-running advertising campaign of all time. Their undeniable charm was based on a fallacy: that chimpanzees are like cheerful, uncoordinated human children. The irony is that the opposite is probably closer to the truth: that humans are chimps who didn't grow up. We got smart instead.

Adult chimps (
Pan troglodytes
) may not be much taller than a ten-year-old but they weigh twice as much and have five times the upper body strength of an adult human. Chimps can recognise themselves in a mirror, vocalise and use sophisticated gestures to communicate. Young chimps laugh when playful or being tickled. They appear to express emotions. They don't have the physiology for speech, but they can learn some human sign language – though without grammar or syntax. They can use a variety of tools – some ‘fish' for termites with twigs; others crack nuts with rocks or sharpen spears with their teeth. They learn from one another. To this extent, different groups of chimps have their own ‘cultures'.

In particular, their sister species the bonobos (
Pan paniscus
), only identified in 1929, seem to approach the common problems of food distribution and reproduction from a much jauntier angle. Whereas chimp groups are run by a team of dominant males, bonobos are like a feminist hippy collective, with sexual contact – male-female, female-female, adult-child – used as the universal social solvent. Anything that arouses the interest of
more than one bonobo results in sex. Unlike common chimps, bonobos often have sex face to face; like them, the males have huge testicles, because the females of both species are serially promiscuous. It's a sperm war: the more sex, the more partners, the better chance of raising your own offspring.

All of this fascinates us, and why shouldn't it? Here are two species, closer to us than they are to the gorillas and with whom we share all but 1.5 per cent of our genetic material, whose behaviour is both like and completely unlike our own. But chimps and bonobos are no mere pit stops on the way to becoming human. Since our paths split from a common ancestor 5 million years ago, the genomes reveal that chimps have ‘evolved' more than we have (meaning that more of their genes have changed as a result of selective pressure than ours). Also, they are much more genetically diverse than humans, suggesting that they were once common and we were rare. Whatever small genetic shifts allowed us to stand on our hind legs, freeing our hands to pinch and grip, and our brains to grow, it isn't a lack in the other species, just a difference. And, as Darwin once expressed it, a difference of degree, not of kind.

There are fewer than 200,000 chimps and bonobos left in the wild. The start of their decline predates human intervention, but we haven't helped: more are eaten as bushmeat each year than are kept in all the world's zoos. Imagine a world without chimpanzees. It's precisely because we can, and they can't, that we should save them.