NERS Review of the Year Part 2 – Animals bring the awe

This is part of a series reviewing last year’s stories, according to theme and topic. This one focuses on nature, surprising in tooth and claw. These are some of my most popular posts (three are in the top ten in terms of views) and rightly so – many of these are awesome in the traditional sense of the word.

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The great bowerbird is both architect and illusionist. He creates a lined avenue of twigs leading to a display area covered in stones. The stones are carefully arranged according to size, which makes the courtyard look smaller and the bird look comparably bigger to a female, watching from the avenue. These “forced perspective” illusions are found in the entrance to Disneyland, various ancient monuments and post-Renaissance Western art. And, apparently, in the nest of a bird.

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This was a mystery a thousand years in the solving. The argonaut octopuses secrete a thin, white, brittle shell called the paper nautilus. In 300BC, Aristotle suggested that the shells were boats, an idea picked up by Jules Verne. But beautiful videos of living argonauts tell a different story – it’s an organic ballast tank. By trapping air inside the shell, the octopus can maintain a constant depth with precise control.

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Arguably the most touching story of the year. Cameras at a Scottish safari park capture the final moments of a chimpanzee called Pansy and the actions of her fellow chimps. Meanwhile, another paper tells of two wild female chimps who carried around their babies’ lifeless bodies, even after they had long since mummified. These tales provide rare glimpses into how one of our closest relatives deal with death.

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Parasitic flatworms wage war on one another in the body of a castrated snail. Like ants and termites, their colonies have a caste of specialised soldiers, with powerful jaws that eviscerate invading worms from other colonies. Until now, the idea of such a division of labour among flatworms would have been laughable. These are creatures that are difficult to imagine living in a colony, much less in an organised one.

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Almost all animal eyes stick to a few basic plans so rare exceptions are always fascinating. This year has a great contender: the nightmarish larva of the sunburst diving beetle. It hunts with a pair of natural bifocal lenses, that allow it to focus on both far and near objects at the same time and with equal sharpness. By looking through different parts of the lens, the beetle gets two pairs of eyes for the price of one (and that’s just one of its four pairs!).

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A drama of sexual tension played out across the surface tension of lakes and streams: when male water striders (pond skaters) try to mate with resistant females, they strum the water surface with their legs. Each vibration risks attracting predators and because the female is underneath, she will bear the brunt of any assault. By creating dangerous vibes, the male intimidates the female into submitting to his advances.

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In autumn, some yellowing leaves develop mysterious green islands that refuse to decay. These turned out to be the work of caterpillars called leaf-miners that live inside the leaf. More amazingly still, the caterpillars use a bacterium called Wolbachia to chemically manipulate the plant and protect their home – treat the caterpillars with antibiotics and the green islands disappear.

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It’s perhaps unsurprising that the toughest biological material ever found should come out of the backside of a spider. But what a spider! The Darwin’s bark spider spins its web over entire rivers and lakes. The main anchor thread can be as long as 25 metres and the main sticky core can be as large as 2.8 square metres. With threads that long, it’s not wonder that they’re also tough. The silk that can resist 10 times more force than a similarly sized piece of Kevlar before rupturing.

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You’re in a game show and there are three doors: there’s a car behind one and goats behind the others. You pick one and your host opens one of the others, inevitably revealing a goat. If you now pick the door with the car, you get it. Do you stick with your pick, or swap to the other door? Few maths problems have caused more grief than the Monty Hall Dilemma and even famous mathematicians have fallen afoul of it. But not pigeons – they’re much better at learning the right call than humans are (you always switch, by the way). And along a similar vein, even brainless slime moulds make decisions in a human-like way.

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This post really captured people’s imaginations and it’s not hard to understand why. Robins can sense the Earth’s magnetic field but they need their right eye to do it. Cover it up, and their internal compass stops working. What’s more, if you blur the image, the compass also fails. It’s another piece of evidence to suggest that robins can literally see magnetic fields, which could appear as a heads-up display of light and shade – a sort of biological “augmented reality”.