Army ants have a reputation as destroyers. As they march through the jungle in battalions several thousand-strong, they supposedly kill all in their path. But this infamy is overblown. There’s no doubting their success as predators, but army ants also bring life wherever they march. They have an entourage of over 550 species that hang around their legions, of which 300 or so depend on the ants for their survival.
Carl and Marian Rettenmeyer spent much of their lives studying army ants. Carl passed away in 2009, but this year, Marian has completed the couple’s masterpiece – a comprehensive catalogue of the animals associated with a single species of army ant Eciton burchellii. Their record is incredible – a menagerie of animals running alongside the columns, tracking them by air, living within the nests and garbage dumps, and even riding on the ants themselves.
This is the second of two interviews, to accompany my latest New Scientist feature on how birds sense magnetic fields. Thorsten Ritz was one of two scientists who blew this field of research open in 2000, with a landmark paper that suggested how migrating birds could detect the faint traces of the Earths’ magnetic field. My interview with his partner, Klaus Schulten, is elsewhere on the blog, along with more background on the topic.
These interviews are meant to provide bonus extras to the other freelance writing I do, acting as a home for great material that would otherwise be cut and lost. And Ritz’s interview is great material. He talks eloquently about the science of the magnetic sense but more importantly, he talks about what it’s like to work in this field – the reasons why progress has been slow, the thrill of crossing disciplines, and the feeling of doing “19th-century science”. I’ve edited the transcript for length, but it’s still long – if you read any of it, read that second half (starting from the fourth question).
It’s now winter in Europe and many small birds are well on their way to warmer climes, migrating over large tracts of land in search of better weather. Along the way, they keep their course with a remarkable supersense – the ability to sense magnetic fields.
This sense is known as magnetoreception. It sounds like a party for an X-Men villain, and it’s also the subject of my latest feature, out in this week’s issue of New Scientist. I talk about how birds sense magnetic fields, using a compass in the eye and a map in the beak. I look at why the magnetic sense has been so fiendishly difficult to study and why it has taken five decades to unravel some of its details.
For the full details, you’ll have to read the feature, but this is the quick version: when light enters the eyes of birds, it excites a molecule called cryptochrome, shunting it into a state when it can be affected by the earth’s magnetic field. The upshot is that you can ‘blind’ a bird to magnetic fields by covering its eyes (and sometimes, just the right one). It’s possible that they may even be able to see the fields as patterns overlaid on top of their normal vision.
One of the reasons that magnetoreception is such a tricky topic (for scientists as well as science writers!) is that it straddles incredible diverse fields of research, including quantum physics, neuroscience and animal behaviour. Only a few scientists can bridge such divides, and I had the pleasure of interviewing two of them for my piece: Klaus Schulten and Thorsten Ritz. Both gave eloquent, insightful and funny interviews that were inevitably pared down into a few short quotes for the feature. Fortunately, I have all the space I need to make that material publicly available.
First up is Schulten, who talks with marvellous clarity about the early days of the research and where it expects it to go. He was warm and jovial, and gave a great insight into how discoveries are made – by connecting dots that no one else can see. I’ve edited it very gently for length, but the words are all his.
Whenever I compile my list of weekly links, I usually end up with more articles from mainstream news sources than I do from science blogs. When I do link to blogs, I tend to go with those written by professional journalists and science writers than those written by scientists. That’s not a reflection on the quality of their writing. I do it simply because I write this blog for a general audience and I want to direct them to material of a similar type. And a lot of science blogs can be far too opaque for the average reader.
There is much talk of blogs being part of a golden age of science writing, where learned people can talk directly to large audiences. I certainly believe this, but I see jargon as one of the biggest barriers in the way. Many blogs fall into the trappings of scientific writing: passive voice, laboured constructions, and roundabout sentences (see this wonderful list for translations of the most common offenders).
And then, there are the words themselves. Some are technical, others are simple words clothed in extra syllables (“armamentarium” anyone?) Every field has its own list; they can be so familiar that it beggars belief that people could not understand them. Skeptical bloggers throw about terms like RCT and placebo, and catchphrases like “correlation is not causality”, as if everyone knows what they mean. Technological writers casually speak of visualisations, infographics and crowdsourcing. Have a look at Carl Zimmer’s famous list of “banned words” for more examples.
Some scientific discoveries are exciting because they have the potential to save lives and revolutionise the way we live. Others are exciting because they fundamentally change the way we view ourselves and the world around us. And others are exciting because they involve a worm with tentacles on its head.
This is the third kind of discovery.
The squidworm looks like a fusion animal, half-squid and half-worm. In fact, it’s all worm, a member of the group that includes familiar earthworms and leeches. It just happens to have ten long tentacles on its head.
The tentacles are elastic and extendable, and they can be longer than the squidworm’s ten-centimetre body. Two of them – the yellower ones – are used for feeding. The other eight are used to breathe, or possibly to feel its way around. Its head also carries two feathery, brush-like structures called ‘nuchal organs’ that act like a nose, picking up chemical smells in the water.
It’s formal name – Teuthidodrilus samae – means squidworm of the Sama, the people who live in the local Philippine islands. “The name was suggested by the Philippino collaborators that took part in the expedition that discovered the animal,“ says Karen Osborn from the Scripps Institution of Oceanography, who first discovered the worm in 2007. Using remote-controlled submarines, Osborn explored the depths of the western Celebes Sea off the eastern coast of Borneo.
Osborn announced the squidworm’s existence last year (although it hadn’t been formally described then). The animal made its debut alongside six other species of deep-sea worms that it’s closely related to. Four of these are ‘bomber’worms – they release glowing fluid-filled capsules from their heads, probably as decoys to draw the attention of predators.
The squidworm has no such defence and it doesn’t seem to be a very strong swimmer either. Like the bomber worms, its flanks are lined by rows of bristled oars that beat in hypnotic waves. But unlike the bombers, the squidworm has a more leisurely pace. It’s certainly no predator; instead, Osborn thinks that it filters food from the bits of matter that sink down from the upper ocean.
Over seven dives, Osborn found 17 of these distinctive creatures and she expects to find many more. She thinks it’s probably fairly common and other related species will soon be discovered. The fact that such a striking animal has only just been discovered says a lot about our ignorance of the deep sea.
The squidworm lives in one of the richest but most mysterious layers – the demersal zone, just above the ocean floor. It’s the largest habitat on Earth, and a haven for undiscovered life. Here, animals can easily evade collection devices towed along the seafloor, while staying under the reach of mid-water nets dragged overhead. To appreciate the richness of life in these waters, you need special submersibles like the ones that Osborn used, which can move about easily and collect local animals without damaging their frail bodies. Who knows what else the subs will discover?
Reference: Biology Letters http://dx.doi.org/10.1098/rsbl.2010.0923
Related: Marine worms release glowing “bombs” to fool predators
If the citation link isn’t working, read why here
The rivers of Africa and South America are full of shocking conversations. Both continents are home to fish that can talk to each other using electric fields: the elephantfishes of Africa, and the knifefishes of South America (including the famous electric eel). Both groups live in dark, murky water where it’s hard to see where you’re swimming. Both have adapted by using electricity to guide their way. Their bodies have become living batteries and their muscles can produce electric currents that help them communicate, hunt, navigate and court.
But both elephantfishes and knifefishes evolved their electric powers independently. Their common ancestors had no such abilities. They are a great example of how two groups of animals, faced with a similar problem, can arrive at the same solution. And this similarity is all the more striking because it is based on the same gene. For a fish, it seems there are only so many ways to be electric.