The Book of Animal Ignorance

by Ted Dewan

  Starfish move using simple hydraulics. They take in seawater through a special sieve-like opening called a madreporite and distribute it internally to all the feet-tubes. By squeezing and sucking water in and out of the feet in sequence, they can move surprisingly quickly. Some species manage three feet a minute.

  Starfish sex is a strictly arm’s-length business. Each leg contains a large sex organ, but short of dissecting them it is impossible to tell male from female. They gather in groups when spawning, the male releases sperm into the water if he detects eggs; the female releases up to two and half million eggs at a time if she detects sperm. The larvae are completely unlike their parents and look more like free-swimming plankton. Eventually they grow arms, sink to the bottom and stick to a rock, before metamorphosing into adults.

  THE STARFISH DINER

  Fully-grown starfish have few predators; their spiny skin is covered in tiny pincers which nip at anything that annoys them. They also ‘groom’ the skin, keeping it clear of parasites. One species, Luidia, just disintegrates into fragments if it gets caught.

  Starfish eat almost anything too slow to escape, particularly mussels and oysters. A square-mile army of starfish was recently sighted off Le Morbihan in France, at a density of fourteen to the square foot, moving slowly across the ocean floor and consuming everything in its path.

  Tapir

  Ancient forest horse

  When Stanley Kubrick cast tapirs alongside early hominids in the opening sequence of 2001: A Space Odyssey, it was because they seemed ‘prehistoric’. He was right: they may look like the result of a night of passion involving a pig and an anteater but tapirs are the last survivors of a large family of mammals that have changed little in twenty million years. At one point they were found on every continent (except Antarctica) but now there are only four species left: three in Central and South America and one on the other side of the world, in South-East Asia.

  Tapirs are perfectly adapted to life in warm, wet forests. They can graze on the forest floor for fallen fruit and browse higher up for green twigs and ferns. Their stout bodies barrel through thick undergrowth at high speed and they are as happy in the water as on dry land. But the key to their early success remains their most distinctive feature, a short, multi-directional trunk – the ultimate accessory for forest life. It gave them greater reach when feeding, functioned as a snorkel for travelling under water, and provided a continuous olfactory read-out on the presence of food, or the possibility of sex.

  FOURTEEN TOES AND ONE FINGER

  But the climate has changed, and cooler, drier conditions have seen forests replaced by grassland, which favours grazing ruminants, not shortsighted, semi-aquatic fruit-chewers. Unlike their closest relatives, horses and rhinos, tapirs haven’t managed this transition, and now all four surviving species are endangered.

  As well as the loss of habitat, tapirs are also threatened by human predation. Hundreds are poached each year for their fatty meat (often sold as buffalo), their durable hide (tapira is a Brazilian Indian word for ‘thick’) and the various parts of their anatomy still used as folk cures for heart disease and epilepsy. In many Amerindian tribes, the Milky Way is known as the ‘Tapir’s Way’, in the same way the American Plains Indians call it the ‘Path of the Buffalo’. In China and Japan, their name means ‘dream-stealer’.

  The Thai word for tapir is P’som-sett, which means ‘mixture’. It comes from the belief that the tapir was made from the leftover bits of all the other animals.

  Other than humans, tapirs are too strong and nimble to have many predators. Occasionally, a big cat will take one on, in which case the tapir simply leaps into a nearby stream and sinks until the cat is forced to let go. Tapirs like walking on the bottom of streams and ponds: it cools them down and allows fish to strip their hide of parasites.

  Tapir calves look very different from their parents: they are striped and spotted, like furry watermelons. This provides surprisingly good camouflage in the dappled shade of the forest, but they still fall prey to the giant anaconda, which likes to swallow them whole. Although we call their offspring ‘calves’, zoologists have now agreed that tapirs are sufficiently different from other hoofed mammals not to call the adults ‘bulls’ and ‘cows’.

  Tapirs are the least well-studied of all large mammals. We don’t know whether they mate for life, how their family groups work, where they sleep, or the function of their strange bird-like whistles. But this is changing. Their importance in the ecosystem of the rainforest has made them a conservation landmark species. Just as they need the forest to survive, so many of the forest fruiting plants depend on the tapir’s digestive tract to propagate. Saving the tapir will help save the rainforest, too.

  Tardigrade

  The bear that wouldn’t die

  Tardigrades are the toughest animals on the planet. Also known as ‘water bears’ and ‘moss piglets’, they sound cute, but don’t be fooled. They live anywhere there’s water – 5 miles down in the ocean; on the polar ice-caps; in radioactive hot springs; on top of the Himalayas; on forest floors; on the bottom of lakes; on wet beaches; in Alpine meadows; in the miniature ponds created in the cups of leaves; in the moss on your roof; on the ground where your dog pees each morning. They are plump, microscopic animals that fall somewhere between the annelid worms and the insects. Only a twentieth of an inch long, they have a head, four pairs of stubby, clawed legs and a sausage-shaped, opaque body. They’re called water bears because of the way they look and move (although they’re more like a section of frayed, rumpled leg-warmer) and moss piglets because moss is one of the best and easiest places to find them.

  A tardigrade in suspended animation is called a ‘tun’, because it looks a bit like a tiny wine barrel.

  INSIDE THE RESURRECTION MACHINE

  There are 800 recorded species of tardigrade, with at least 10,000 still to be named and they are distinctive enough to have their own phyla. Most land-dwellers feed on plants and fungi, but many are carnivorous, sucking up nematode worms, rotifers and other tiny creatures. The water-dwellers (who can live 100,000 to the pint) seem to survive without eating at all for long periods, although some are parasites, living on sea cucumbers and barnacles. Many species are all female. As they aren’t speedy at getting around (‘tardigrade’ means ‘slow-stepper’), they rely on the wind or splashing raindrops to move them to new habitats. Under those circumstances, being able to fertilise your own eggs is a definite advantage: you can populate a new clump of moss all by yourself. Other species reproduce sexually, in a topsy-turvy kind of way (the female inserts a tube into the male and steals his sperm). Tardigrade eggs are spectacularly beautiful, shaped into multi-pointed stars and dimpled spheres that look like chic lampshades, although their practical function is to keep their contents moist and safe from being squashed.

  What really sets tardigrades apart is their ability to enter a state of suspended animation. If their water supply dries out, they dry out too. All life processes come to a complete halt and they become totally inert – but they are not dead. This condition, known as cryptobiosis, was first identified in 1776. Some scientists believe it may hold the clue to the origins of life itself. The tardigrade expels all its water and breaks down its cell fats into a sugar called trelahose, which binds and protects all its vital organs. Then it waits – for as long as a hundred years – for a single drop of water to revive it.

  In this ‘dead’ state, tardigrades are practically indestructible. They have been frozen to within a degree of absolute zero (–272°C) and heated to temperatures of 151°C. They have been placed in liquid helium for a week, and given doses of radiation a thousand times greater than the fatal dose for a human. They have been immersed in chemicals and squeezed by pressures six times greater than those at the bottom of the ocean; but like living granules of instant coffee, with one drop of water, back to life they come.

  Termite

  Family values

  Termites have evolved the most sophisticated family organ
isation of any animal and it’s based around monogamy. Despite living in colonies containing millions of individuals, breeding termites mate for life. Some species only have one king and queen per colony; others have several and, unlike those of ants or bees, these are proper marriages not brief flings: there are couples still mating years later. This has helped make termites, with ants, the most successful insects of all: if you added all 2,600 termite species together, they would account for 10 per cent of the planet’s total biomass. Unfortunately their high-fibre diet means they also produce 11 per cent of global methane emissions, second only to ruminants like cows and sheep.

  HOW DOES YOUR WOOD SOUND?

  But life doesn’t always run smoothly, even for termites. In the species Zootermopsis nevadensis the divorce rate is running at about 50 per cent. Sometimes the males walk out; often the female invites in a new male with predictably violent results. Touchingly, rejected termites tend to take up with one another. Marriage leaves the male termite relatively unaffected, although he usually dies first. The queen, however, can swell to 300 times her original size, as her ovaries expand. The queen of the Indian mound-building termite (Odontotermes obesus) lays an egg a second, or more than 80,000 a day. If the nest is attacked, the workers have to drag her to safety, as she is too fat to move of her own accord.

  To make things worse, termites are in the middle of an identity crisis. In 2007, DNA research revealed that they are actually cockroaches. Their former order Isoptera (‘equal wing’) has been abandoned and they have been moved into Blattodea (blatta is Greek for cockroach). The theory is that they evolved from their cockroach-like ancestors when they developed the ability to eat wood.

  Didgeridoos are made from eucalyptus logs hollowed out by termites.

  It’s the blind workers who do the wood-munching, feeding the rest of the colony from their mouths or bottoms. They are like mini-cows, with a multi-chambered stomach to break down cellulose. Their guts are home to 200 types of microbes which all help turn the wood into energy. Studies of these tiny organisms are being funded by the biofuel industry to see if they hold the key to extracting clean-burning fuel from corn. In some species, workers arrange their droppings into combs which grow fungi, ensuring a supply of rich protein, even during the dry season.

  A termite nest is the most complex animal structure not built by us. The external mound can be over 25 feet high, protecting the nest from the fierce sun, acting as an air-conditioning duct by releasing the heat and carbon dioxide generated by the termites and their fungus gardens and replacing it with fresh oxygen. The Formosan subterranean termite (Coptotermes formosanus) even fumigates its nest with naphthalene to repel ants and nematode worms. As it doesn’t occur naturally, no one knows how – or from what – it is made.

  Termites can burrow through concrete. In North America, they cause more damage than fires and floods put together; the annual global termite damage bill now exceeds $5 billion.

  Termites are one of the most popular culinary insects: they contain 75 per cent more protein than rump steak. In the Amazon basin, the Maue tribe barbecue them while the Kayapo fry them in their own juices or use them crushed as a condiment. In Nigeria you can buy termite stock cubes.

  Toad

  When amphibians explode

  Few animals spook us like the toad. The witch’s right-hand animal, they have been feared throughout history as ugly, poisonous creatures of the night. Touching them might give you warts and meeting their stare could turn you epileptic.

  In East Anglia, to become a ‘toadman’ was to make a pact with the Devil, the most dangerous initiation ritual of British folk magic: all your power was focused in the bone of a toad, which no one else was allowed to see or touch.

  Wearing the legs torn from a toad guarded against skin disease. Carrying its tongue made you irresistible to women. Breast cancer could be cured by rubbing a live toad over your chest, and the best protection against witches was to bury a toad in a bottle near your door or hearth. Killing them was strictly taboo.

  Despite all the bad press, toads, taxonomically speaking, are members of the frog family. There are 350 species and the main differences are skin and teeth. Frogs tend to have tiny teeth and smooth skin; toads have no teeth and thick, warty skin, and usually walk rather than hop.

  ‘Toady’ (as in ‘sycophant’) comes from ‘toad-eater’, one half of an eighteenth-century pair of con artists, who would swallow a toad in public and then beg his quack doctor-partner to cure him with a ‘magical elixir’.

  Also, unlike most frogs, toads are poisonous. They secrete a milky fluid from their warts and from a pair of glands behind their eyes – the ‘toad spittle’ of legend. In some species this venom contains hallucinogenic compounds and can be ‘milked’ for recreational use. Unfortunately, it also contains powerful steroids which cause irreparable damage to the heart. Licking or kissing toads is likely to make you sick long before it gets you high.

  Twenty tons of toads are squashed on British roads every year. This is because they have followed the same path, century after century, to ancient breeding ponds, which often means crossing busy roads. Purpose-built subterranean toad tunnels have helped, easing the passage of as many as 1,500 toads in a single evening.

  ‘Toad-in-the-hole’ was originally steak encased in batter, until steak became too expensive and was replaced by sausages. The name was taken from a now-forgotten public craze of the nineteenth century. Hundreds of examples were reported of live toads being discovered entombed in the middle of ancient rocks. ‘Toad-in-the-hole’ hysteria peaked in the 1830s when William Buckland, the Oxford Professor of Geology, buried a number of toads in stone blocks to test their survival skills. Although some lived for as long as two years, most died and public fascination waned.

  A more recent toad mystery took place in a Hamburg pond in 2005, when toads started exploding during the mating season. More than a thousand toads, swollen to three times their usual size, crawled out of the water, making eerie screeching noises, and blew up, propelling their entrails up to a yard away.

  Initial suspicions of a virus or industrial pollution turned out to be wrong. The toads were being attacked by super-smart crows. The birds had worked out that, with a single strike through the toad’s chest, they could remove its liver. The toad’s own defence mechanism did the rest. As they puffed themselves up to intimidate their attacker, they forced their own intestines out through the wound at high pressure, in a kind of fatal hernia.

  Tuatara

  Three-eyed loner

  Most species described as ‘living fossils’ struggle to fully justify the claim but not the tuatara. This ancient reptile looks like an iguana, but it isn’t a lizard. Nor is it a dinosaur, although it has changed little since the days of the giant reptiles. It’s a sphenodon, or ‘wedge tooth’, the last member of an order that once covered the planet. The tuatara has survived for two reasons. Firstly, it happened to find itself on the small land mass that became New Zealand about eighty million years ago, as it split from Gondwanaland, the southern super-continent, before mammals had established themselves. And second, it found a way of adapting to a colder climate.

  Most of the sphenodons disappeared with the dinosaurs; those that didn’t got hustled out of their niches by mammals. The tuatara ploughed its own furrow quite happily for millions of years, until the mammals finally reached them, paddling canoes. With the canoe-mammals came others, most notably dogs and rats. The tuataras were gradually driven from the mainland and now survive only on islands dotted around New Zealand’s coast.

  Tuatara means ‘spiky back’ in Maori. The Maori once ate them but only the men – a woman who broke the rule risked being pursued and killed by the entire tuatara population.

  Their main disadvantage in the battle with mammals is metabolism. Tuataras are the most primitive of all living reptiles. Their brain is tiny, more like an amphibian’s than a lizard’s. Their heart and circulatory system are also rudimentary, making them extremely cold-blooded, and
they live on islands which are often wind-battered and chilly. Out of necessity, ‘do it slowly’ has become the tuatara’s motto. They grow more slowly than any other reptile. It takes them fifteen years to reach sexual maturity and even then, the females only manage to produce a clutch of eggs every four years and they take over a year to hatch. Their method of hunting is to sit outside their burrows at night waiting for beetles, worms, crickets, or – best of all – a young tuatara to toddle past. Their method of defence is to sit inside their burrow waiting for the danger to go away. That’s no challenge for a sprightly rat. In 1981, the island of Whenuakura had a population of 200 tuataras. By 1984 they had gone, replaced by a colony of rats.

  Several features set the tuatara apart from their lizard cousins. They can live for well over a hundred years. They don’t have teeth but all-in-one serrated jawbones: in old tuataras these jaw ‘teeth’ are worn smooth, leaving them to gum their way through slugs and earthworms. Also, unlike the doubly endowed lizards, tuataras have no penis: they reproduce by pressing their bottoms together, like birds and (probably) dinosaurs.

  HOW TO CATCH A TUATARA

  Oddest of all is the third eye in the middle of their forehead. Although scales grow over it by the time they are six months old, it is a real eye with a lens, retina and a nerve connection to the brain. It appears to be light-sensitive and might help in regulating body temperature. Temperature matters to a tuatara: they live cheerfully in conditions that would trigger hibernation in most reptiles (10°C), so heat can kill them. Rising temperatures also pose a more serious threat. As with turtles and crocodiles, the sex of the hatchling is determined by the heat of the egg. The warmer northern colonies of the 55,000-strong tuatara population are now producing twice as many males as females.