It’s a cat-and-mouse tale with a difference. The lesser salmon catfish has been found feasting on mice. But how does it catch them?

Some catfish are known to ambush unwary pigeons at the water’s edge, giving them the nickname “”. But the lesser salmon catfish might just be an opportunist, gobbling up animals when they drown.

A survey of 18 lesser salmon catfish (Neoarius graeffei) from Ashburton river in northern Australia, suggests the fish can consume large quantities of small land animals when given the chance — almost half of the catfish had mice in their bellies.

“That is a lot, and a rare finding,” says Peter Lisi, an aquatic ecologist at the University of Wisconsin-Madison.

The stomachs of some catfish contained as much as 95 per cent small mammals, with two fish having three animals each in their stomachs.

Lesser salmon catfish can grow to half a metre long and weigh up to 1.5 kilograms. They are a common species in dryland rivers of north-western Australia,  so their diet is important to understanding the local ecosystems.

They were thought to feed mainly on aquatic invertebrates and plants, with the occasional addition of fruit and terrestrial insects, especially during the floods in the wet season.

And though a few freshwater fish species are known to dine on land vertebrates — African plucking a swallow out of thin air, for example — it is rare for them to eat so many.

The catfish had been mostly eating spinifex hopping mice (Notomys alexis, pictured above), which are around 10 centimetres long. As their name suggests, the mice get around by jumping. There are no reports of these mice intentionally spending any time in the water.

But heavy rain might have a role to play. “These mice often live in small colonies within a single burrow system,” says of the Centre for Fish and Fisheries Research at Murdoch University, Perth, who led the research, “so collapse or flooding of one or multiple burrow systems along the Ashburton river could have inadvertently introduced them into the water.”

“When several catfish are targeting mice all at once, it suggests that a large pulse of mice are entering the river,” says Lisi. “We still do not know how catfish gain access to mice or how often it occurs, or at what scale mice support river food webs. Because large fish often survive through feast and famine periods, big meals like this are ecologically relevant.”

If this is what is happening, the mice could be in greater danger as climate change kicks in.

“Climate projections for north-western Australia indicate that we’re going to see both longer periods of drought and more intense rainfall events,” Kelly says. “Changes in periods of flooding could possibly be altering the food web of these fish.”

Journal reference: Journal of Arid Environments,

Read more: Global browning: Why the world’s fresh water is getting murkier

Bottlenose dolphins have been observed chattering while cooperating to solve a tricky puzzle – a feat that suggests they have a type of vocalisation dedicated to cooperating on problem solving.

of Dolphins Plus research institute in Florida and her colleagues at the University of Southern Mississippi presented a group of six captive dolphins with a locked canister filled with food. The canister could only be opened by simultaneously pulling on a rope at either end.

The team conducted 24 canister trials, during which all six dolphins were present. Only two of the dolphins ever managed to crack the puzzle and get to the food.

The successful pair was prolific, though: in 20 of the trials, the same two adult males worked together to open the food canister in a matter of 30 seconds. In the other four trials, one of the dolphins managed to solve the problem on its own, but this was much trickier and took longer to execute.

But the real surprise came from recordings of the vocalisations the dolphins made during the experiment. The team found that when the dolphins worked together to open the canister, they made more vocalisations than they did while opening the canister on their own or when there was either no canister present or no interaction with the canister in the pool.

Importantly, the researchers were able to show that the increase in chatter was directly related to the canister-opening task as opposed to social interactions between the dolphins.

During the trials when one dolphin opened the canister unaided, one or more of the other dolphins was present nearby, watching the task. On these occasions, there was no increase in chatter. The team concluded that the increased chatter during the joint canister opening was related to the task itself, and not to the presence of another dolphin.

“This is the first time that we can say conclusively that dolphin vocalisations were used to solve a cooperative task,” says Eskelinen.

Unlike most dolphin vocalisations, the so-called “burst pulses” the dolphins made are audible to humans as a squawking sound. We already knew that dolphins use burst pulses during social interaction and echolocation. But according to , a marine ecologist at Oregon State University, these new findings suggest that burst pulses may have another sophisticated purpose.

“This study clearly shows that dolphins use vocal communication to jointly solve problems”, says Torres. “The results point toward the possibility of a dolphin language that enables team problem solving.”

Journal reference: Animal Cognition, DOI:

Read more: Behind the smile: What dolphins really think; Talking gibbonish: Deciphering the banter of the apes

Struggle to survive

In the cloud forests of Central and South America live masters of disguise. Some species of orchid have evolved an unusual solution to pollination in forests with few bees: part of their flowers look and smell like mushrooms.

The flowers of some Dracula orchids have a lower petal – known as a labellum – that closely resembles the mushrooms that live in their forest habitat. The flowers also emit chemicals identical to those given off by some fungi.

żěè¶ĚĘÓƵs had long speculated that this mimicry attracts fungus gnat flies, which lay their eggs on mushrooms and act as pollinators. However, the exact importance of appearance and scent to the orchids’ disguise had not been studied before.

To study what it is that attracts forest flies, a team led by , a biologist at the University of Oregon in Eugene, created 3D-printed replicas of the flowers of one species of Dracula orchid (Dracula lafleurii).

The researchers swabbed some of these replicas with a scent extract from the real orchid, and left others unscented. They then tested the printed flowers in the orchid’s natural habitat – the forests of the Ecuadorian Andes – to see what the flies made of the impostors.

They found that the orchids are playing an even more subtle game than we thought.

Sure enough, the scented replica flowers attracted three times as many flies as unscented ones. This suggests that their scent, in addition to their looks, attracts unwitting insect pollinators looking to lay their eggs on mushrooms.

Spotting patterns

But the team found that the Dracula flowers also attracted flies in another, less obvious way.

Aside from its mushroom-mimicking labellum, the sepals of Dracula lafleurii have a characteristic spotted pattern. By painting the replica sepals, the researchers showed that flies were more attracted to those with a spotted pattern than those that were striped or did not have a pattern.

The reason for this is not clear, but it could be that the insects confuse the spots for other flies, and land on the flowers in the hope of finding a mate.

Although various species of Dracula orchid have been proposed as fungi mimics, this is the first time that scientists have managed to separately study their visual and olfactory tactics, says Policha.

“Few organisms scream evolution like orchids – they have developed some absolutely wild adaptations,” says , an entomologist at the American Museum of Natural History in New York. “This study reveals just how deceptively sophisticated orchids can be in luring pollinators.”

In the future, Policha’s group plans to document some of the numerous mushroom and insect specimens that live in the Ecuadorian forest – many of which have only been discovered recently, he says.

At least four other plant genera are believed to mimic fungi. However, this is not a well-studied phenomenon in plants, so may be more widespread than we know, says co-author Bryn Dentinger.

Journal reference: New Phytologist, DOI:

Here I am!

Journal reference:

IN SOUTHERN Turkey, there are fires that never go out. The flames have been alight for millennia, but the source of the methane that fuels them was a mystery – until now.

The seeping gas feeds dozens of half-metre-high flames at the site, called Yanartas, Turkish for “flaming stone”. The flames are believed to have inspired Homer to create the fire-breathing Chimera in his Illiad.

But the gas fuelling the flames was not derived from biological processes – such abiotic methane is only supposed to form at temperatures much higher than conditions at Yanartas.

Now Giuseppe Etiope of the National Institute of Geophysics and Volcanology in Rome, Italy, may have found the answer. Working with Artur Ionescu of the Babes-Bolyai University in Cluj-Napoca, Romania, he has shown that ruthenium, a rare metal found in the igneous rocks beneath the site, can act as a catalyst, allowing methane to form in the lab at temperatures below 100 °C – similar to the temperatures at Yanartas (Geofluids, ).

“These results demonstrate that abiotic methane production is possible at much lower temperatures than is typically suspected,” says Michael Whiticar of the University of Victoria in Canada.

The experiment is the first to show that the untreated form in which ruthenium occurs at Yanartas can act in this way.

“There could be considerable quantities of abiotic methane elsewhere in the world,” says Etiope. “We could be looking at a new source of hydrocarbons.”

This article appeared in print under the headline “Flames that never die traced to their source”

A fossil meteorite unlike anything seen before has been uncovered in a Swedish quarry. The mysterious rock may be the first known piece of the “bullet” that sparked an explosion of life on early Earth.

Roughly 100 fossil meteorites have emerged from the limestone quarry west of Stockholm, which is being mined for flooring. All of the meteorites are part of an iron-poor class called the L chondrites. They date back about 470 million years to the Ordovician period, when Earth experienced a mysterious burst of new species.

Now miners working in the Swedish quarry have found a meteorite fragment that is not an L chondrite. Analysing its microscopic crystals, at Lund University and his colleagues found that the rock dates to the same time period but is of a kind completely unknown to science.

Cloud of destruction

About 515 million years ago, our planet was going through an evolutionary slump. A burst of diversity that happened during the Cambrian period had tapered off, and few new types of animals were emerging. Mysteriously, about 25 million years later life sprang back into action in the early part of the Ordovician, generating loads of species. So what triggered the second explosion?

Fossil meteorites from the quarry suggest that during this time, impacts were tens to hundreds of times more frequent than they are today. The meteorites may have been born when two asteroids collided and broke apart between Mars and Jupiter. The larger object spawned the cloud of L chondrites that bombarded Earth for about 10 million years. According to one popular idea, this intense meteor shower caused just enough destruction to open up ecological niches and drive life to diversify into a richer assortment. But the fate and identity of the smaller asteroid has long been a mystery.

The fact that the latest fossil comes from the same rock layers as the L chondrites suggests that it is a piece of that second asteroid, says Schmitz. The theory says that most of the smaller asteroid was vaporised during the collision, so it also makes sense that only scant fragments of it would remain.

Crash, bang, wallop

at Durham University, UK, agrees. “The team may at last have identified the impactor responsible for the break-up of the parent body of the L chondrite meteorites,” he says. In which case, he adds, it is a direct remnant of one of the most violent events in our solar system’s history.

“This was the largest documented asteroid break-up event of the past 3 billion years,” says Schmitz. “The asteroid impact at the end of the Cretaceous period, believed to have killed the non-avian dinosaurs, was tiny in comparison.”

Journal reference: Earth and Planetary Science Letters,

What has the sun been smoking? The most complete photographs yet taken of the sun’s atmosphere show patterns that resemble smoke rings. These may help astronomers unravel what drives the solar wind, the stream of charged particles that flows from the sun and permeates the solar system.

The patterns, some of which also resemble expanding bubbles and mushrooms, arise in the sun’s outer atmosphere, or corona, where the solar wind is thought to emanate from. Although similar formations were spotted there before, their cause had eluded astronomers.

Now, using a high-resolution eclipse-imaging technique, a team led by at the Brno University of Technology in the Czech Republic has linked the strange patterns to plasma eruptions on the sun’s surface, called solar prominences.

The team came to this conclusion by superimposing about 60 separate photographs of solar eclipses, during which the corona is visible as a white halo around the blacked-out sun. The resulting composite images provided a new view of the sun that spanned all the way from the surface to far out in the corona: by contrast, previous images of such high resolution have typically been confined to one region or another.

The researchers were able to link particular patterns to particular prominences, and concluded that prominences are the likely cause of the patterns. Below you can see a prominence close to the sun’s surface and a “smoke ring” marked by the arrow.

(Image: Miloslav DruckmĂĽller)

Because they are much smaller than other solar eruptions – like flares or coronal mass ejections – prominences had previously been thought to have a relatively minor effect on the sun’s atmosphere, and therefore also on the solar wind.

The new hi-res composite images change that, suggesting instead that prominences could be one of the driving forces for the solar wind, since to create the smoke rings, and other patterns in the corona, they must be creating much larger atmospheric disturbances than previously thought, with a much longer range.

“Our findings are the first to suggest that prominences are sources of significant wave generation in the inner corona, and could therefore contribute to the acceleration of solar wind particles,” says team member .

Space protection

“This strengthens the theory that prominences are one of the drivers of the solar wind,” agrees at the University of Glasgow, UK, who was not involved with the study.

The solar wind helps create auroras in Earth’s atmosphere, the tails of comets and the protective bubble encapsulating the solar system called the heliosphere. It can also interfere with spacecraft by giving rise to electromagnetic disturbances around Earth known as space weather. But despite all this, the mechanism behind the solar wind remains something of a mystery.

“These observations will hopefully help us better understand the life cycle of solar prominences and their connection with the rest of the heliosphere, ultimately providing a better insight into how to protect ourselves against damaging space weather,” Labrosse says.

Journal reference: