by Ted Dewan
Walrus
A violent lunch companion
The word ‘walrus’ may be from Dutch walros (‘shore-steed’) and its Latin name Odobenus rosmarus means ‘tooth-walking seahorse’, but walruses look nothing like horses. They are almost as round as they are long; they have no visible ears and they drag themselves along by their teeth. They also change colour when heated, from off-white to pink to cinnamon brown. A beach heaving with basking walruses looks like a skip-load of deformed cocktail sausages.
The walrus in Lewis Carroll’s 1871 poem ‘The Walrus and the Carpenter’ was inspired by a stuffed specimen in Sunderland Museum, of which only the head remains. The poem, in turn, inspired John Lennon’s acid anthem ‘I Am the Walrus’ on Magical Mystery Tour.
Walruses are inordinately fond of seafood. They enjoy cockles and mussels, crabs, shrimp, snails and octopus and can wolf down more than 6,000 clams in a single meal. Clams bury themselves in the seabed, so the walrus first has to unearth them. To do this, it brushes the sediment away with a flipper and it almost always uses the right-hand one. There are no southpaw walruses. It was long assumed that all animals are ambidextrous, but recent research has shown this is not so. As well as walruses, whales, chickens and toads tend to lead with their right, whereas frogs and lizards favour the left.
Another way that walruses feed is to create a high-pressure hose effect using their lips and tongues to blast the seabed and expose their lunch. This creates a thick murk of sand and debris, so, rather than using their small eyes to identify prey, they slide along feeling the bottom with their moustaches. These are composed of more than 400 incredibly sensitive whiskers, known as vibrissae, Latin for ‘vibrators’. A grazing walrus can move each of them independently.
THE ARCTIC SUPERMARKET
Walruses suck as well as blow. When they find a clam, they hold it firm in their lips, create a vacuum around it and use their tongue like a piston to extract the soft tissue. As a special treat, they hoover up seagulls from underneath or suck the brains of seal pups out through their nostrils, a party trick also used by young Inuit in Greenland to impress tourists. Walruses have a sucking power three times stronger than the average Dyson, which explains why their stomachs are full of small pebbles.
Medieval merchants used to pass off walrus tusks as unicorn horns. They are canine teeth that never stop growing; in a large male they can be 3 feet long. Apart from helping them haul themselves on to ice floes, they are mostly for show. Walrus society is simple: the bigger the male, the more impressive the tusks, the more lady walruses make themselves available.
Mating among walruses is much like a sub-zero version of a Club 18–30 holiday. The females lounge provocatively on the ice, while being ogled by a pack of alpha-males bobbing around in the water, trumping, clacking, roaring, rasping and occasionally gouging chunks out of one another. Unlike those in Club 18–30, however, the female will only mate with one male. Walrus sex takes place underwater and it’s impressive stuff. The male’s penis contains a bone almost as long as its tusks, which guarantees fail-safe operation in even the coldest Arctic seas.
Wasp
Sugar and paper
Of the thousands of species of wasp out there, there are only two that regularly bother us: the Common wasp (Vespula vulgaris) and the German wasp (Vespula germanica). There’s not much to chose between them: both live in colonies and fashion delicate spherical paper nests, both have a nasty retractable sting, both cause a huge fuss at late summer picnics. Wasps, of course, suffer the great misfortune of not being bees: they don’t make us honey, their markings are stark and uncuddly and their behaviour seems thuggish in comparison to the mystical dances and complex social life of their furry cousins. This is unfair; for a start, bees are really just vegetarian wasps. Each of them has a job to do and without the voracious appetite of the wasp many insect pests would overrun our gardens.
The appetite is not quite what it seems. Like bees, most of the wasps we see are sterile females, but in spite of their impressive mouthparts, they have a very simple digestive tract, which means they can only eat sweet nectar. They kill and scavenge tirelessly, but not for themselves. Their jaws are used to chew up protein for the endlessly hungry larvae back at the nest. Then, in return for bits of bacon sandwich or beetle, they get a blob of sweet, nutritious ‘soup’ from the larva’s mouth. But at summer’s end, this food source runs out. Its breeding work done, the commune disperses; next year’s queens find a sheltered place to spend the winter, while everyone else gradually dies off. This is when worker wasps – now unemployed and unfed – become a nuisance to humans. In the last few, purposeless weeks of their lives, before cold weather finishes them off, they seek alternative sources of sugar, in our kitchens, orchards and picnics. It’s now that most human–wasp interaction occurs – sometimes with fatal consequences, for wasp and human.
Often these interactions culminate in one of the humans claiming they are being attacked by a ‘hornet’. The hornet (Vespa crabro) is the largest and noisiest of the European social wasps, which no doubt explains why people have long been terrified of it. But, in fact, its sting has much less effect on humans than that of a bee. Bees have evolved their venom as a defence against honey-stealing vertebrates, including beasts the size of bears and badgers, whereas a hornet’s poison is intended mainly for use on its invertebrate prey. Analysis of hornet venom suggests that a fatal dose for a human (unless he was allergic to it) would be something like a thousand stings.
It’s a bad idea to kill a wasp: dying wasps emit a pheromone that alerts its nest-mates to danger, so you may be surrounded within seconds.
There is an important exception. The Asian giant hornet (Vespa mandarinia) of Japan, also known as the yak-killer, is the super-predator of the wasp family. They are enormous – like flying thumbs, with a quarter-inch sting. They are fast, strong and merciless – ten of them can take out an entire honeybee colony in a matter of hours, tearing off the bees’ heads with their terrifying jaws. Their venom is strong enough to dissolve human tissue and they kill over fifty people a year. But the Japanese get their own back in style: they serve the larvae raw as hornet sashimi and deep-fry the adults, which are reputed to taste like sweet prawns.
Whale
Supersized songsmith
Fifty-five million years ago, small hoofed carnivores started to move from the land back into the sea. Those wonderful pictures of legs becoming fins and tails, bodies becoming longer and more streamlined, nostrils moving back and up, seem to run the evolutionary clock backwards. DNA evidence now shows us that whales have nothing to do with other water-based meat-eaters like seals and walruses; their closest living relative is the vegetarian hippo, with deer, camels and pigs as very distant cousins. It’s one of evolution’s most compelling stories: how a clumsy, crocodile-shaped otter ends up producing the largest, most graceful and mysterious of all the creatures on the planet.
Blue whales were only caught after the invention of the ‘grenade’ harpoon in 1868. In 1931, 29,000 were killed in one season. There are now fewer than 5,000 – one whale for every 8,500 cubic miles of their ocean habitat.
The blue whale is the largest animal that has ever lived by a huge margin: thirty times heavier than an African elephant, the next largest mammal. The biggest dinosaur weighed less than half as much: some female blue whales can lose as much as 50 tons when feeding their young. A newborn blue whale is the same weight as a female elephant: it puts on 14 stone a day, 8 lb an hour. When fully grown, its heart is the same size as a family car, processing 2,000 gallons of blood, pumping 60 gallons a beat, with an aorta large enough for a five-year-old child to swim through.
Whales grew large because the buoyancy of water meant they could – nothing so heavy could survive on land; the energy needed to move and feed would be too great. But for a warmblooded animal living in the sea is problematic: it’s a desert – there’s nothing to drink. And it’s cold: heat travels twenty-four times faster in water. Being large helps, as it redu
ces the surface-to-weight ratio, but the real star of whale survival is blubber. It not only acts as an insulating overcoat and life-jacket (it’s less dense than seawater); it also stores the water extracted from food and provides a handy on-board supply of nutrients when food is scarce.
WHY THE BIG NOSE?
Communicating in water is also a challenge. Smell is useless, sight limited and touch is tricky when you have fins rather than fingers. But sound waves travel four times faster under water, and whales have turned the ocean itself into a sophisticated communication system. Whale song is the loudest noise made by any single animal: some songs are so low in frequency that they can be felt thousands of miles away. The massive head of the sperm whale focuses sound into a burst that can stun a giant squid but it also acts as a kind of acoustic retina, a giant IMAX sound screen through which it interprets its dark world. The half-hour songs of the humpback whale contain grammatical rules: sounds are combined into structures that operate like syntax, packing the song with millions of discrete units of information. Whales sing in different dialects depending on where they’re from, and sing different songs in different places at different times of the year.
Whether these songs are sat-nav read-outs, shipping forecasts, personal ads or epic poetry, we will never know. What we do know is that military sonar and general noise pollution in the sea has reduced their carrying range by 80 per cent and many stranded whales have severe inner ear damage. We may not hunt whales as once we did, but we still torment them.
Woodlouse
The backyard shrimp
Woodlice are land-based crustaceans, and, despite appearances, are much more closely related to shrimps and lobsters than they are to millipedes or centipedes.
They have blue blood and still breathe using gills, These are attached to the pairs of pleopods (literally, ‘swimming feet’) on their abdomen and contain a branching network of moist tubes that allow them to extract oxygen from air, although a woodlouse will survive quite happily in water for up to an hour.
Woodlice have a rich array of nicknames: ‘sow bugs’, ‘ball bugs’, ‘armadillo bugs’, ‘slaters’, ‘grammerzows’, ‘chiggy pigs’, ‘cheeselogs’ ‘bibble bugs’, ‘cud worms’, ‘coffin cutters’, ‘monkey peas’, ‘pea bugs’, ‘granny-ants’, ‘granfers’, ‘Billy Bakers’ and ‘tiggyhogs’. In Holland they are called pissebed (literally ‘piss-in-the-bed’). This is because they don’t urinate: their porous shell also allows them to expel their waste as ammonia vapour rather than liquid urine. They produce more nitrogenous waste for their size than any other animal.
The porous shell also means they are vulnerable to dehydration. Their tendency to clump together in large groups helps keep them moist and protects them from predators. Toads, shrews and centipedes are all keen on woodlice. Blowfly larvae also burrow into woodlice and eat them from the inside. The woodlouse spider (Dysdera crocata) lives on nothing else and has specially adapted fangs for piercing their shells.
Woodlice were eaten as a cure for stomach upsets, rather like Rennies – their shell is made from calcium carbonate, which neutralises the acid in the stomach.
Woodlice do use their bottoms to drink. Small forked tubes called uropods suck water into their anuses. They’re not fussy eaters either. They prefer rotting vegetation, but in lean months their own faeces will do. There’s a New Zealand species, the sea slater (Scyphax ornatus), that survives mostly on drowned honeybees. Their odd personal habits make them good news in a compost heap and their fondness for munching through rubbish has led to them being employed by natural history museums to clean delicate animal skeletons.
Woodlice are members of the Isopod order (meaning ‘equal feet’). There are 3,500 species and they’ve been around for 160 million years. They carry their young in pouches, moult regularly and live for about two years. Not all of them clump together in damp crevices. The desert woodlouse (Hemilepistus reaumuri) pairs for life, navigates by the sun and lives in organised colonies of burrows where the young do the housework. They can walk several miles a day.
It’s tough being a male woodlouse. Not only can females give birth without mating (parthenogenesis), but males infected with a certain bacterium actually turn into females.
The Deep sea isopod (Bathynomus giganteus) is a giant aquatic woodlouse that lives on the icy darkness of the ocean floor and hoovers up dead whales. They are white, 2 feet long and weigh as much as a decent-sized lobster.
Woodlice are perfectly edible. In his polemical pamphlet Why Not Eat Insects? (1885), Vincent M. Holt considered their flavour superior to shrimp and gave a recipe for a woodlouse sauce for fish.
Woodpecker
The tongue that listens
The woodpecker’s tongue is one of the most amazing of all animal organs, so much so that it often gets cited by creationists as ‘proof’ that evolution is flawed. In some species it can extend to fully two-thirds of the bird’s body length, is covered in sticky saliva, has vicious barbs and has an ‘ear’ at the end of it. In fact, tongue structure of the woodpecker is very similar to that of most other birds: it’s just longer, presumably because this delivered the evolutionary advantage of being able to reach deeper into the tree for insects. The secret is a series of wafer-thin hyoid bones, that fold up like an accordion in a fluid-filled sheath when the tongue is not being used. As the woodpecker sticks out its tongue, powerful muscles contract near the base, forcing the bones forward and the tongue out of the bill. Relaxing the muscles brings it back inside. When a woodpecker is born, its tongue is anchored near its ears, much like a chicken’s. As it grows, the hyoid sheath gradually extends around and over the skull, when it fuses with the back of the nostrils. As for the ear on the tongue’s tip, this is a concentration of pressure-sensitive nerve endings called Herbst’s corpuscles that feel the tiniest vibrations of insect prey.
My father told me all about the birds and the bees, the liar. I went steady with a woodpecker till I was twenty-one.
BOB HOPE
There are over 200 species of woodpecker, and each has a particular speed and rhythm of drilling, some reaching sixteen blows per second. Every time a wood-pecker brings its head to a halt, the force is equivalent to a thousand times the force of gravity (or 250 times the force an astronaut is subjected to during lift-off). The reason that their heads do not shatter is a sponge-like cartilage cushion that absorbs most of the shock. Also, every time the woodpecker strikes a blow, a muscle pulls the brain-case away from the beak.
Woodpecker drumming isn’t searching for food. It’s a species ‘signature’ used to communicate and attract mates. Woodpeckers often choose materials where the resonance is high – dead trees, metal drainpipes or wooden eaves. They drum at different rates when insect-hunting or excavating nests. In 1995, a pair of Northern Flickers (Colaptes auratus) drilled 200 holes into the foam insulation of the shuttle Discovery’s external tank, delaying its launch.
Green woodpeckers (Picus viridis) are also known as rainbirds – hearing their distinctive ‘laughing’ call means rain is on its way. This dates back to an early version of the Genesis story, where the woodpecker refused to help God excavate the rivers and oceans and was punished by being forced to peck wood and drink rain. The bird once had forty English vernacular names including Hewhole, Wudewale and Galley Bird, but the one still used is ‘Yaffle’. Most people assume this refers to its laugh but it actually means ‘to eat greedily’. Which green woodpeckers do, as anyone who’s ever seen one attacking an anthill will testify. They can get through 2,000 ants in a single sitting.
Worm
Wiggly woo woo
The animal kingdom is subdivided into thirty-four categories called phyla. There is some disagreement among biologists about the precise number and placing of the divisions, but everyone agrees that more than half of them (usually seventeen) are made up of various kinds of worm. There may be more species of beetle, but there are more individual worms in the world than any other type of creature. No matter how many cattle there
are in a field, the worms under the soil will always outweigh the cows on top of it.
Nematodes, or roundworms, are parasitic worms found almost everywhere on earth from the ocean floor to the human gut. They are the most numerous animals on the planet, ranging from a hundredth of an inch to 27 feet long. There are about 40,000,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000 nematodes all told and their DNA is 75 per cent identical with that of human beings. Most nematodes are benevolent, humbly servicing the ecosystem, but some are dangerous parasites that can cause river blindness, elephantiasis and hookworm anaemia. Then there are flatworms and segmented worms, spoon worms and peanut worms, ribbon worms and horsehair worms. Velvet worms live in old leaves and rotting logs. They paralyse animals and liquidise them with saliva. Acorn worms live in U-shaped burrows on the seabed. They eat and excrete mud. Those little coils you see on the beach at low tide are acorn worm droppings. All worms except paddle-worms are hermaphrodites. Pseudoceros bifurcens is a flatworm that lives 60 feet underwater in Queensland, Australia. It performs a mating dance called ‘penis-fencing’. The worms spend up to an hour trying to inject each other with sperm: whoever wins gets to be the male. Ribbon worms will eat their own bodies if their food supply runs out. They can eat up to 95 per cent of themselves and still survive.