Koala means “no water” in the now extinct Dharuk language of south-eastern Australia. Koalas hardly ever have to drink because their diet consists entirely of eucalyptus leaves, which are 50 per cent water. They can even tell the age of the leaves by their smell. To qualify as lunch they have to be between a year and 18 months old, as young leaves have almost no nutritional value and older leaves contain poisonous prussic acid. Eucalyptus is so low in energy that koalas spend 20 hours a day asleep, like sloths.
Geckos can walk vertically up glass and scientists have recently discovered how. Their feet are covered in half a million tiny hairs, each of which splits into hundreds more with diameters less than the wavelength of light.
This creates a powerful bond between the electrons in the two surfaces. One square centimetre of adhesive tape based on this principle has already been manufactured. If enough can be made to cover a human hand, you could hang by it from the ceiling.
An experiment with rhesus macaques revealed that they would “pay” to look at pictures of the faces and bottoms of high-ranking females, by forfeiting their usual reward of a glass of cherry juice. With low-ranking females, however, the researchers had to bribe them with an even larger glass of juice before they would pay any attention.
The male blanket octopus takes sexual discretion to a whole new level. He is 40,000 times smaller than the female and his technique involves tearing off his mating arm, placing it somewhere on her body and then swimming off to die.
Given that this is roughly equivalent to a herring nudging a blue whale, it’s unlikely she’s even aware of him. Meanwhile, his disengaged arm crawls into her gill slit, where it can live for as long as month, until her eggs are mature. She then retrieves it, tears it open like a packet of café sugar and sprinkles the sperm over her eggs.
The nocturnal, flightless kakapo from New Zealand is one of the world’s rarest birds. As well as being easy prey for rats and dogs, its mating ritual does them no favours. The male constructs a mating court on top of a mountain, excavating several shallow “bowls” connected by a series of tracks, which he keeps scrupulously clean. Every evening, he hunkers down in each of his bowls in turn, pumps up a special air sac and emits a sequence of low-frequency “booms” that can be heard three miles away.
It may take him months to attract a female, during which time he can lose half his body weight. Some females shuffle 20 miles. If both are still in the mood, they mate for 10 minutes and then she walks home again and tries not to get eaten.
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