Panama’s San Lorenzo forest reserve is around the size of Manhattan. For two years, this small area was host to 102 scientists, working together to count everything that crept and crawled. They came from 17 countries, and converged upon a half-hectare of the forest, about the size of half a rugby pitch. They dug into the soil, and ascended into the 40-metre-tall treetops with ropes, balloons, and a giant crane. They unleashed fogs, set up sticky traps, and hacked into pieces of wood.
Together, they were part of the largest ever systematic attempt to answer a disarmingly simple question: in a patch of tropical rainforest, how many species of insects and other arthropods are there?
After collecting the critters in 2003 and 2004, and analysing the material for eight years, they got an answer: 6,144 species in that patch of forest. Using computer simulations to scale that up, they estimate that the entire 6,000-hectare Manhattan-sized forest is home to around 25,000 arthropod species.
When the fruit bat Pteropus allenorum was finally described by scientists, it was already extinct. One specimen of the bat was shot in Samoa in 1856, skinned, stored in alcohol, and shipped to the United States. It spent the next 153 years, inconspicuous and ignored, on a shelf in the Academy of Natural Sciences in Drexel University. When bat specialist Kristofer Helgen visited the museum, he immediately recognised that it was a new species. Sadly, it was too late. There are no fruit bats in Samoa nowadays, so the jar on the shelf represents our only encounter with this now-extinct animal.
The fruit bat’s story isn’t an original one. The beetle Meligethes salvan was collected from the Italian Alps in 1912 and sat in Frankfurt’s Senckenberg Museum until it was described in 2003. In the intervening time, the valley from which it came had been almost entirely destroyed in the process of building a hydroelectric power plant. Biologists searched in the nearby valleys but couldn’t find it. The beetle may be extinct.
These examples show that the shelves and drawers of the world’s museums are among the planet’s most diverse habitats—ecosystems brimming with different species, many of which have never been seen before.
People often think that discoveries are made when biologists see new species in the field, and immediately recognise them as such. That’s largely not true. Field biologists often collect their specimens en masse, taking them back to their respective institutions, and keeping them in storage until they get a chance to peer at them properly. This means that many of the planet’s new species are sitting pretty in jars and drawers, gathering dust while they wait to be formally described.
How long is this shelf life? For the bat, it was 153 years, and for the beetle, 92. On average, it’s around 21 years, according to a new study from Benoît Fontaine from the Natural History of Museum in Paris.
A.ervi attacks a pea aphid, by Alexander Wild
In a British lab, a wasp has become (locally) extinct. And then, another wasp follows it into oblivion. That’s odd because these two insects are not competitors. They don’t attack one another, and they don’t even eat the same food. They do, however, remind us that it’s very hard to predict how the decline of one species will affect those around it.
Some consequences are obvious. If an animal goes extinct, its loss will cascade up and down the food web, so that its predators will suffer but its prey will probably thrive. But food webs are webs for a reason, rather than a set of isolated linear “food chains”. Consequences can ripple across, as well as up and down.
If wasps didn’t exist, picnics would be a lot more fun. But the next time you find yourself trying to dodge a flying, jam-seeking harpoon, think about this: without wasps, many of your ingredients might not exist at all. Irene Stefanini and Leonardo Dapporto from the University of Florence have found that the guts of wasps provide a safe winter refuge for yeast – specifically Saccharomyces cerevisiae, the fungus we use to make wine, beer and bread. And without those, picnics would be a lot less fun.
S.cerevisiase has been our companion for at least 9,000 years, not just as a tool of baking and brewing, but as a doyen of modern genetics. It has helped us to make tremendous scientific progress and drink ourselves into stupors, possibly at the same time. But despite its significance, we know very little about where the yeast came from, or how it lives in the wild.
The wild strains do grow on grapes and berries, but only found on ripe fruits rather than pristine ones. And they’re usually only found in warm summery conditions. So, where do they go in the intervening months, and how do they move around? They certainly can’t go airborne, so something must be carrying them.
Stefanini and Dapporto thought that wasps were good candidates. They’re active through the summer, when they often eat grapes. Fertilised females hibernate through the winter and start fresh colonies in the spring, feeding their new larvae with regurgitated food. In the digestive tracts of wasps, yeasts could get a ride from grape to grape, from one wasp generation to the next, and from autumn to spring.
When Rachel Carson wrote her famous book Silent Spring, she envisioned a world in which chemical pollutants killed off wildlife, to the extent that singing birds could no longer be heard. Pesticides aside, we now know that humans have challenged birds with another type of pollution, which also threatens to silence their beautiful songs – noise.
A man-made world is a loud one. Between the din of cities and the commotion of traffic, we flood our surroundings with a chronic barrage of sound. This is bad news for songbirds. We know that human noise is a problem for them because some species go to great lengths to make themselves heard, from changing their pitch (great tits) to singing at odd hours (robins) to just belting their notes out (nightingales). We also know that some birds produce fewer chicks in areas affected by traffic noise.
Now, Julia Schroeder from the University of Sheffield has found one reason for this. She has shown that loud noises mask the communication between house sparrow mothers and their chicks, including the calls that the youngsters use to beg for food. Surrounded by sound, the chicks eat poorly. “City noise has the potential to turn sparrow females into bad mothers,” says Schroeder.
Even though most spiders are harmless to us, many people suffer from a crippling fear of them. Imagine then, what a grasshopper must feel. The threat of venomous fangs isn’t something that the insects can shrug off. It’s a perpetual danger that chemically alters their bodies, triggering changes that ripple through an entire ecosystem.
Now, Dror Hawlena from Yale University has found just how far-reaching these changes can be. In an elegant experiment, he showed that the fear instilled by spiders can extend into the very soil, affecting how quickly leaf litter decays.
Hawlena raised red-legged grasshoppers in outdoor enclosures, half a metre wide. Half the enclosures contained a single nursery-web spider, whose mouthparts had been glued shut, so they couldn’t actually kill any of the hoppers. Their presence, however, was felt.
Last September, I travelled to Peru to meet a fascinating scientist who is mapping the Amazon by plane. The piece was published in Wired UK earlier this year, and I’m reprinting it here now. This was one of the most enjoyably things I got to write last year. I hope you enjoy it too
A small, twin-propeller plane flies over the Amazon rainforest in eastern Peru. The scale of the vegetation is extraordinary. The tree canopy stretches as far as the eye can see — an endless array of broccoli florets bounded only by haze and horizon. Greg Asner, 43, has seen the rainforest from this vantage point many times before, but he still stares out of the window in rapt fascination.
This patch of forest in the Tambopata National Reserve is rich with life, even by the Amazon’s standards. A 50-hectare patch of forest — the size of as many rugby pitches — contains more plant species than the whole of North America. “We might as well be exploring Mars,” says Asner. “These are areas where no human has ever been. There’s no access.”
Access isn’t a problem for Asner. Behind him are three state-of-the-art sensors of his own devising which, as the plane flies along, take the forest’s measure. “We’re trying to do something really new,” He says. “This world is changing and it requires science that isn’t incremental.” Using the technology he’s developed, Asner is mapping the shape and size of the trees, down to individual branches, from two kilometres above. He can measure the carbon stored in trunks, leaves and soil. He can even identify individual plant species based on the chemicals they contain. With wings and lasers, Asner is conducting one of the most ambitious ecology studies ever staged. He accumulates more data in a single hour than most ecologists glean in a lifetime. With this data, he aims to influence governments, steer the course of climate-change treaties and save the forests over which he soars.
It turns out that if you unleash giant snakes into a place that didn’t previously have giant snakes, the other local animals don’t fare so well. That seems obvious, but you might be surprised at just how badly those other animals fare.
Since 2000, Burmese pythons have been staging an increasingly successful invasion of Florida. No one knows exactly how they got there. They normally live in south-east Asia and were probably carried over by exotic wildlife traders. Once in America, they could have escaped from pet stores or shipping warehouses. Alternatively, overambitious pet owners could have released when they got too large for comfort. Either way, they seem to be thriving.
With an average length of 12 feet (4 metres), the pythons are formidable predators. They suffocate their prey with powerful coils, and they target a wide variety of mammals and birds. The endangered Key Largo woodrat and wood stork are on their menu. So are American alligators (remember this oft-emailed photo?). Conservationists are trying to halt the spread of the giant snakes, out of concern that their booming numbers could spell trouble for local wildlife.
Michael Dorcas from Davidson College thinks they are right to be concerned. In the first systematic assessment of the pythons’ impact, Dorcas has found that many of Florida’s mammals have plummeted in numbers in places where the snakes now live.
A leaf falls from the rainforest canopy, but it never hits the ground. Instead, it becomes trapped by nets of sticky fungi. While other lost leaves litter the forest floor, this one has joined the jungle’s mezzanine level – a layer of litter suspended in mid-air and hanging by a thread.
The fungi belong to a single genus called Marasmius, which extend networks of root-like filaments through the air. They act like a web that catches falling matter from the branches above. They have gone unappreciated, but Jake Snaddon from the University of Oxford has found just how important they can be.
By snaring leaves, the fungi provide room and board to insects, spiders and other canopy creepy-crawlies that might otherwise be confined to the ground. When Snaddon removed the fungi, the numbers of these animals plummeted by 70 percent.
I’ve got a new piece in Nature about a newly discovered species of “yeti crab” that farms bacteria on its arms, then eats them. It lives in the deep ocean, near seeps that belch out methane. The bacteria living on its bristly arms (hence the name “yeti crab”) feed off the seeping gases, and the crab encourage the bacteria to grow by rhythmically waving their arms.
Go to Nature to read the full piece. Meanwhile, I loved this quote from lead author Andrew Thurber, which gets across how much there is left to discover about the oceans: “It was a big surprise. There’s a tonne of them, they’re not small, and they’re six hours off a major port in Costa Rica.”
(Photos by Andrew Thurber)