Archive for November, 2008

Australiana #5 – Stingrays

By Ed Yong | November 30, 2008 8:00 am

Following last week’s parrotfish, here’s another underwater snap taken at the Whitsunday Islands. This is a bluespot stingray, and it was later joined by a second individual.

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More pics and a video beneath the fold…

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CATEGORIZED UNDER: Animals, Fish

Attack of the killer mice – introduced rodents eat seabird chicks alive

By Ed Yong | November 29, 2008 10:00 am

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Blogging on Peer-Reviewed ResearchAs Charles Darwin learned several centuries ago, islands are havens for evolution. Newcomers to these isolated worlds find themselves unshackled from the predators that dogged them on the mainland. They celebrate their freedom by diversifying into a great variety of species. But predators still have ways of tracking them down, and following the footsteps of sailors is one of them. By killing adults and eating eggs, introduced predators such as rats, cats and stoats are responsible for nine in ten of the bird extinctions since 1600.

A Gough Island mice sites amid a grisly pile of chick bodies.Now, conservation agencies are getting serious about introduced predators. As an example, they have spent increasingly large budgets in recent years on the eradication of rats from troubled islands. Smaller stowaways like mice typically escape the conservationists’ wrath, and between 2001 and 2005, twenty-five times less money was spent on dealing with them. After all, mice are smaller and less opportunistic than rats and pose very little threat to seabirds.

Or at least that was what scientists used to think. In 2005, Ross Wanless, Peter Ryan and colleagues from the University of Cape Town found that on Gough Island in the south Atlantic, mice had developed sinister appetites. They were eating the chicks of local seabirds alive (see image below).

Infrared footage shows mice feeding on a chick.

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Why blog? The Meme returns…

By Ed Yong | November 28, 2008 10:32 am

For some reason, I’ve only just discovered the navel-gazing blogger meme that started at Nature Network a few weeks ago. But I’ve written up a shed-load of science this week and I’m feeling lazy and introspective. So better late than never…

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CATEGORIZED UNDER: Personal

Pain in the eye of the beholder

By Ed Yong | November 27, 2008 8:30 am

Blogging on Peer-Reviewed ResearchIt goes without saying that we are capable of noticing changes to our bodies, but it’s perhaps less obvious that the way we perceive our bodies can affect them physically. The two-way nature of this link, between physicality and perception, has been dramatically demonstrated by a new study of people with chronic hand pain. Lorimer Moseley at the University of Oxford found that he could control the severity of pain and swelling in an aching hand by making it seem larger or smaller.

Moseley recruited 10 patients with chronic pain in one of their arms and asked them to perform a series of ten hand movements at a set intensity and to a set pace. The volunteers had to watch their arms as they went through the motions. On some trials, they did so unaided, but on others, they viewed their arms through a pair of binoculars that doubled their size, a pair of clear-glass binoculars that did not magnify at all, or a pair of inverted binoculars that shrunk the image. 

On each trial, Moseley asked the recruits to rate their pain on a visual sliding scale. He found that they were in greater pain after they had moved their arms – no surprise there. But the amount of pain they felt depended on how large their arm appeared to them. They experienced the greatest degree of extra pain when they saw magnified views of their arms, and took the longest amount of time to return to normal. Perhaps more surprisingly, the “minified” images actually evoked less pain than normal.

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Heroes in a half-shell show how turtles evolved

By Ed Yong | November 26, 2008 1:55 pm

Blogging on Peer-Reviewed ResearchClad in hard, armoured shells, turtles have a unique body plan unlike that of any other animal. Their shells have clearly served them well and the basic structure has gone largely unchanged since the time of the dinosaurs. But this unchanging nature poses a problem for anyone trying to understand how they evolved and until now, fossil turtles haven’t provided any clues. All of them, just like their living descendants, have fully formed two-part shells.

Cowabunga.jpgBut three stunning new fossils are very different. They belong to the oldest turtle ever discovered, which lived about 220 million years ago in the area that would become China. Unlike today’s species, its mouth had a full complement of small, peg-like teeth but even more amazingly, it had a feature that distinguishes it from any other turtle, either living or extinct – it only had half a shell.

The ancient turtle was unearthed by Chun Li (no, not that one) from the Chinese Academy of Sciences, who called it Odontochelys semitestacea, a name that literally means “toothed turtle in a half-shell”. It was a small animal, just 35 cm from snout to tail, and its shell consisted of just a plastron (the bottom half) and not a carapace (the top half).

Li’s team believes that this incomplete shell represents an intermediate step along the evolutionary path to the modern version. To them, Odontochelys‘s anatomy settles debates about how the group’s distinctive shell evolved, which animals they were most closely related to and what sort of lifestyles the earliest members had. It’s a true hero in a half-shell.

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Clean thoughts can soften moral judgments

By Ed Yong | November 26, 2008 7:30 am

Blogging on Peer-Reviewed ResearchThroughout our language, the vocabulary of physical cleanliness is also used to describe moral cleanliness. We describe saints as pure and thieves as dirty; consciences can be clean and sins can be washed away. But more and more, psychological studies tell us that these concepts are entwined in a very real way. The act of cleaning, or even just thinking about the concept of cleanliness, can influence a person’s moral compass, swinging it towards a less judgmental direction.

This isn’t the first time that I’ve blogged about this. Two years ago, Chen-Bo Zhong and Katie Liljenquist found that volunteers who dredged up a past misdeed were more likely to think of words related to cleaning or show a physical preference for cleaning products. This “Lady Macbeth effect” is reminiscent of the infamous Shakespearean character and her failed attempts to wash her hands of spilt blood.

Simone Schnall and colleagues from the University of Plymouth have expanded on Zhong and LIllenquist’s study by showing that the effect works in the opposite direction. Not only can feelings of moral muck trigger a desire for physical cleanliness, cleanliness can also change how seriously people view a moral transgression.

They asked 40 volunteers to a rearrange 40 sets of four words into sentences. Through this word-game, they ‘primed’ 20 of the volunteers with thoughts of cleanliness by interspersing half of their sets with cleaning-related words, such as pure, washed, clean, immaculate or pristine. The other 20 volunteers only saw unconnected neutral words in all of their sets.

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Fossilised embryos are the work of bacteria

By Ed Yong | November 25, 2008 7:30 am

Blogging on Peer-Reviewed ResearchAnimal fossils are usually the remains of hard structures – bones and shells that have been petrified through enormous pressures acting over millions of years. But not all of them had such hard beginnings. Some Chinese fossils were once the embryos of animals that lived in the early Cambrian period, some 550 million years ago. Despite having the consistency and strength of jelly, the embryos have been exceptionally well preserved and the structure of their individual cells, and even the compartments within them, have been conserved in all their beautiful, minute detail.

Fossilembryo.jpgThey are a boon to biologists. Ever since the work of Ernst Haeckel in the 19th century, comparing the development of animal embryos has been an important part of evolutionary biology. Usually, scientists have to piece together the development of ancient animals by comparing their living descendants. But the preserved embryos give the field of embryology its very own fossil record, allowing scientists to peer back in time at the earliest days of some of the earliest living things. But how did these delicate structures survive the pressures of the ages?

Elizabeth Raff from Indiana University has a plausible answer. Her experiments suggest that fossil embryos are the work of colonies of ancient bacteria, which grew over the dead clumps of cells and eventually replaced their organic matter with minerals. They are mere casts of the original embryos.

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CATEGORIZED UNDER: Bacteria, Palaeontology

Faulty connections responsible for inherited face-blindness

By Ed Yong | November 24, 2008 8:30 am

Blogging on Peer-Reviewed ResearchHave you ever seen someone that you’re sure you recognise but whose face you just can’t seem to place? It’s a common enough occurrence, but for some people, problems with recognising faces are a part of their daily lives. They have a condition called prosopagnosia, or face blindness, which makes them incredibly bad at recognising faces, despite their normal eyesight, memory, intelligence, and ability to recognise other objects.

Edface.jpgProsopagnosia can be caused by accidents that damage parts of the brain like the fusiform gyrus – the core part of a broad network of regions involved in processing images of faces. That seems straightforward enough, but some people are born with the condition and their background is very different. They lack any obvious brain damage and indeed, brain-scanning studies have found that the core face-processing areas of their brains are of normal size and show normal activity.

But these studies were looking in the wrong place – the core regions aren’t the problem, it’s the connections between them that are faulty. Different parts of the brain are connected by tracts of ‘white matter‘ – bundles of nerve cell stalks that transmit messages between distant regions. They are the equivalent of cables that link a network of computers together and in people born with prosopagnosia, these neural cables are shredded or missing, even though the individual machines work just fine.

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Australiana #4 – Parrotfish

By Ed Yong | November 22, 2008 12:54 pm

Buying an underwater case for my digital camera was an excellent decision. This shot was taken at Pickford Reef in the Whitsunday Islands.

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CATEGORIZED UNDER: Animals, Fish

Parasites keep red tides at bay

By Ed Yong | November 21, 2008 8:30 am

Blogging on Peer-Reviewed ResearchOver the past decade, some coastal waters have started turning red with alarming frequency. The cause is not some Biblical plague, but dense concentrations of microscopic algae called dinoflagellates. Red tides can often contain more than a million of these cells in a mere millilitre of water. Many are harmless and essential parts of the ocean environment, but others produce toxins that can kill local wildlife and risk the health of humans who eat their poisoned flesh.

Redtide.jpgThese “harmful algal blooms” are more common in warm waters that mix poorly and are unusually rich in nutrients. Their increasing frequency has been blamed on numerous causes, from natural causes, to agricultural run-offs to increasing sea temperatures caused by climate change. But, as is becoming increasingly apparent in ecology, you’re not getting a complete picture of a habitat if you don’t know find out what the local parasites are up to.

Aurelie Chambouvet from the Station Biologique found that the algae responsible for red tides are themselves the victims of other parasitic species of dinoflagellates called Amoebophrya. The parasites act as an natural alga-stat that keeps the local algae populations under a tight leash. The red tides are what happens when that leash breaks.

Chambouvet’s team discovered the abundance of these parasites by taking water samples from an estuary of the Penze River in northern France over three consecutive years,. They used multi-coloured glowing antibodies designed to recognise and stick to molecules unique to both the host species and their parasites. The fluorescent glows revealed a life cycle that, like those of most parasites, is full of brutality and exploitation.

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CATEGORIZED UNDER: Ecology, Invasive species, Parasites
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