IELTS Academic Reading Practice Test 420

The sea otter, Enhydra lutris, is one of the most distinctive animals of the North Pacific. It is a member of the weasel family that spends almost its entire life in the sea, usually floating on its back, and it is one of the very few mammals apart from primates that regularly uses tools. An adult male can weigh more than 40 kilograms and reach a length of about 1.5 metres, while females are somewhat smaller. Unlike seals and whales, the species has no layer of blubber, and it depends instead on the densest fur of any mammal: up to a million hairs on a single square inch of skin.

That coat is both the otter's protection and its vulnerability. Fur traps a layer of air next to the skin, keeping the animal warm in water that would quickly kill a human without a suit. But the fur must be kept scrupulously clean for the air layer to work, which is why otters spend hours each day grooming, rolling in the water and combing the coat with their forepaws. The arrangement is also the reason the species was hunted so intensively: a pelt of exceptional quality was worth a great deal of money.

Because fur alone cannot keep such a small, warm-blooded animal warm in cold water, the otter has an unusually high metabolism. It eats roughly a quarter of its body weight every day, feeding on sea urchins, crabs, clams, mussels, abalone and fish, and it spends much of its waking life searching for them. A typical dive lasts a minute or two and reaches depths of ten to thirty metres, though considerably deeper dives have been recorded. Prey is often carried to the surface and broken open on the otter's chest, with a stone used as a hammer or an anvil.

Otters are social animals and often rest in groups known as rafts, which may contain anything from a handful of animals to more than a hundred. In California, otters wrap themselves in strands of kelp before sleeping so that they are not carried out to sea by the current; elsewhere they often hold paws. Females with pups are particularly attentive. A mother carries her pup on her chest, wraps it in kelp when she dives, and feeds it for several months, during which she may lose a great deal of weight. Pups are not waterproof when they are born and cannot dive properly until their fur matures.

The otter's appetite has effects that reach far beyond the animal itself. Sea urchins graze on kelp, and where urchins are numerous they can strip a kelp forest to bare rock. By eating urchins, otters keep their numbers in check and allow the kelp to flourish. Kelp forests shelter fish and hundreds of other species, and they absorb carbon dioxide from the water. For this reason, ecologists describe the otter as a keystone species: a predator whose influence on its ecosystem is out of all proportion to its numbers.

The otter's fur made it a target as soon as European and Russian explorers reached the North Pacific. The survivors of the expedition commanded by Vitus Bering, which was wrecked on an island off Kamchatka in 1741, returned with pelts that soon commanded high prices in China, and within a few decades hunters from Russia, Britain and the United States were working their way along the coast from Alaska to California. The trade was brutally efficient. Estimates of the original population vary widely, but by the early twentieth century only a small fraction survived, perhaps a thousand or two animals scattered across a remnant of the former range.

Protection came in 1911, when the United States, Britain, Russia and Japan signed a treaty — the North Pacific Fur Seal Convention — that ended the commercial hunting of sea otters at sea. A few populations had survived. In 1938 a small group was discovered near Bixby Creek in California, and that remnant became the southern sea otter, which is still classified as threatened. Further north, animals had held on around the Aleutian Islands and Kamchatka.

Recovery has been slow and uneven. Reintroductions in the 1960s and 1970s moved animals from Alaska to British Columbia and Washington State, and those populations have grown steadily. In California, otters have spread along the central coast but have not returned to the south, and a translocation of about 140 animals to San Nicolas Island in 1987 met with only limited success. New threats have appeared as well.

In the 1990s, researchers in Alaska noticed that otter numbers were falling sharply in the Aleutian Islands and concluded that a small number of killer whales had begun hunting them, an unusual choice of prey that may have followed a decline in the whales' usual food. In California, bites from great white sharks are a leading cause of death, although the sharks do not eat the otters.

Oil is another danger. Because otters depend on clean fur, a spill can kill a large number of them, and the species is also vulnerable to disease and to the disturbance of the kelp forests on which it depends. Today the total population is estimated at something over 100,000, most of it in Alaska and Russia. That is a recovery, but not a restoration, and whether the species can ever return to the southern part of its range remains an open question.

On a beach with breaking waves, the water does not simply arrive and stay. Every wave that breaks pushes a volume of water towards the shore, and that water has to go somewhere before the next wave arrives. Most of it returns seaward in a broad, slow movement across the whole surf zone. Occasionally, however, it gathers into a narrow, fast channel known as a rip current and flows out to sea at a speed that can surprise even strong swimmers. Rip currents are among the leading causes of drowning on beaches around the world, yet they remain difficult to predict.

Rip currents are closely tied to the shape of the beach. Sandy shores are rarely flat. Waves tend to build ridges of sand called bars, with deeper channels between them, and the pattern of bars and channels may change from one week to the next. On a beach of this kind, the water returning to the sea naturally takes the path of least resistance: through a gap or hollow in a bar rather than over its crest. A rip current is therefore not a random event but a consequence of the way sand and water interact.

The sequence begins when a group of larger waves breaks on the shore and pushes more water onto the beach than can drain away in the usual manner. The sea level close to the shore rises slightly, a phenomenon known as wave set-up. The surplus water flows seaward, and where the surf zone contains a channel it funnels into it. Flow that was spread across hundreds of metres becomes concentrated into a stream perhaps ten to thirty metres wide, and because the same volume of water must pass through a much smaller space, its speed increases. It is this narrowing, rather than any mysterious pull from the ocean, that explains the strength of the current.

A rip is best understood as part of a circulation system. Water moves along the beach within the surf zone, pushed by waves that arrive at a slight angle, and then turns seaward through the rip. This longshore flow feeds the current, which is why a rip can keep running for hours even though the waves are constantly changing. The current is fastest in a narrow core, and its surface speed is usually greater than the speed near the seabed, because the flow is slowed by friction with the sand.

Measurements made with floating buoys carrying satellite receivers have given a clearer picture of how fast rips move. A typical rip flows at about half a metre per second; the strongest measured exceed two metres per second, which is faster than a world-class swimmer can sustain. Radar installations and video cameras on clifftops have since made it possible to follow several currents at once and to compare their behaviour with the waves that produced them. It is worth remembering, however, that most of these measurements come from a small number of beaches that researchers have been able to study in detail.

Popular accounts often call these currents 'rip tides', but the name is misleading: the tides influence when and where rips form, but a rip is not a tidal stream. Nor is it an undertow, a term that properly describes the slower movement of water back along the seabed beneath the surf. A person caught in a rip is carried out to sea rather than dragged downwards, and the current will usually release them beyond the breaking waves, where it loses speed and spreads out.

Rips are not all alike. Some are fixed features of a beach that reappear in the same place for weeks; others, often called flash rips, appear without warning where one section of the shore receives larger waves than another. In both cases the surface of the water gives clues. Because the flow is smoother than the surrounding surf, a rip often appears as a darker, calmer strip between lines of breaking white water, sometimes carrying sediment or foam out to sea.

The danger arises because people try to swim against the current. Fighting a rip directly is exhausting, and a swimmer who does so may be swept further out. Lifesavers advise swimming parallel to the shore until out of the current's pull, or, if that is impossible, floating and signalling for help.

In Australia, where the surf is heavy and much of the population lives near the coast, rip currents are associated with a substantial share of drownings, and lifeguards carry out tens of thousands of rescues each year. Worldwide figures are much less reliable, because many coastal countries do not keep detailed records. In some countries, schools now include rip current safety in the curriculum for children who live near the coast.

Predicting where and when rips will form is another matter. Forecasters can identify the conditions in which they are likely, and some national weather services issue daily risk assessments for popular beaches. But the precise location of a rip depends on details of the beach and of the waves that are rarely known in advance. Researchers have experimented with radar, video cameras and computer models, and the picture has improved, yet no system can say where a rip will appear on a particular beach tomorrow. In the meantime, the most effective safety measure remains education: teaching people to recognise the calmer, darker water and to know what to do if they are caught in it.

Walk into almost any large toy shop and the organisation of the shelves tells you something before you have read a single word. One aisle is pink and filled with dolls, prams and craft sets; another is dark blue and dominated by cars, construction kits and figures of superheroes. In 2012 a group of parents in Britain began a campaign, Let Toys Be Toys, asking retailers to stop signposting toys as suitable for one sex or the other. Their argument was simple: signs and labels tell children what they are supposed to like, and limit what they feel entitled to choose. Several large chains responded by removing 'boys' and 'girls' signs from their toy departments, an outcome the campaigners regarded as a modest victory.

The campaigners' case rests on a substantial body of research into how toys are marketed. Analyses of catalogues and television advertisements, carried out repeatedly since the 1970s, have found a consistent pattern. Toys shown with boys are more often vehicles, weapons, machines or construction sets, and the images emphasise action, speed and competition. Toys shown with girls are more likely to involve dolls, domestic settings, jewellery and appearance, and the images emphasise care and cooperation. Boys in these images are usually shown moving; girls are usually shown sitting or standing still.

Does the packaging create the preference, or merely reflect it? Developmental psychologists have established that children sort the world by sex remarkably early. By the age of two or three, most can label themselves and others as boys or girls, and they show a marked interest in same-sex peers and activities. By the time a child can read the word 'boys' above a shelf, they have already absorbed a great deal about what boys are expected to enjoy. Children notice very quickly which toys are intended for them and which are not. On this view, a shop sign confirms a preference rather than creating one.

There is evidence pointing the other way. Experiments in which the same toy is presented in different colours or packaging have produced mixed results, and many of the studies are small. Yet children are continually revising their ideas about what is appropriate for their sex, and the information they receive from adults, friends and the wider culture shapes those ideas over months and years. A single label may be trivial; thousands of them, repeated across shops, catalogues and birthday presents, are not.

The strongest objection to the campaign comes from those who argue that the differences are not entirely manufactured. Boys, on average, are more interested in wheeled toys and in rough, physical play than girls, and the difference appears early, before most children have been to school. A much-cited study of young monkeys, in which males were more likely than females to handle a toy with wheels, is often used to support the idea that such preferences have deep roots. Yet even researchers who accept a biological contribution rarely claim that it explains everything.

Averages describe groups, not individuals, and the overlap between boys and girls is enormous. Nor does an early preference tell us how strong it will remain, or how it will be shaped by the reactions of others. A boy who is mocked for pushing a pram is learning something that no packaging taught him.

This is why several commentators argue that the campaign, whatever its merits, has partly missed the point. Signs above shelves are the most visible part of a much larger system. The colour of the box, the photographs on it and the way a product is described all carry the same message, and none of them disappears when the sign comes down. Meanwhile the range of toys on offer has not obviously widened: a construction toy marketed to girls is often the same product in different colours, with a different set of figures.

There is also the question of what neutrality means in practice. When retailers remove gendered signs, the result is usually not a mixture of dolls and diggers on the same shelf but an arrangement organised by theme, with construction sets in one place and art materials in another. Critics point out that the toys girls are encouraged to cross over to are frequently those associated with boys, while traffic in the other direction remains rare. Neutral shelving, on this view, may simply make the boys' aisle the default.

My own position is that the campaign is right about the labels but wrong to expect very much of them. Removing signs is cheap, harms nobody and slightly widens the range of toys a child may feel able to ask for. That is worth doing. It is not, however, a solution to the problem the campaigners have correctly identified. The pressures that steer children towards particular toys come chiefly from other children and from adults they know, and those pressures are not removed by a shop's decision about signage. Anyone who wants a real change has to look at the toys themselves, and at the way that people respond when a child chooses the unexpected one.

It is also worth remembering that the pink aisle is a recent invention. The rigid division of the toy market by sex took shape in the later twentieth century, and there is no reason to suppose that it is permanent. Retailers, after all, follow demand as much as they shape it.