Extreme Nature

Keenest sense of smell (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© Mark Carwardine

Anything that can attack and kill the largest animal that ever lived, the blue whale (see (#litres_trial_promo)), 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 (#ulink_e67d63a9-02a2-5bee-b899-4a4fc8acfe4c)

© John Shaw/NHPA