The hairy legs of water striders are artfully designed to strike a balance between the water capillary action and gravity, Chinese researchers have discovered.
Spacing of the water striders’ leg hairs are optimised so they are close enough not to penetrate the water’s surface during impact Photo: Tim Vickers/Wikimedia Commons
They found the spacing of the insect’s leg hairs fits a formula that takes into account the contact angle of the hairs and fluid mechanics to ensure maximum load-carrying capacity and floating stability.
The results, reported today in Proceedings of the Royal Society A not only provide an insight into the remarkable ability of these insects, but has implications for the design of miniature rafts and water strider-inspired robots that can float stably and move easily across water.
Nature abounds with examples of water-repelling surfaces such as the lotus leaf and insects’ wings that have already inspired a number of technological advances.
“Many researchers have tried to understand how the hairy structures render legs or wings of some insects water repellent from the point of view of surface physics and chemistry,” says Associate Professor Huiling Duan, from the Department of Mechanics and Aerospace Engineering at Peking University.
Previous research had suggested these hairy surfaces were superhydrophobic, hence their ability to repel water.
“In fact, water repellency of hairy surfaces depends on the size, spacing and orientation of the hairs in micro-scale,” says Duan.
To investigate how hairs interact to repel water, Duan and colleagues examined the layout of the tiny hairs, or setae, on water striders’ legs and fly wings.
They found the spacing of the water striders’ leg hairs, and the hairs on a fly’s wing, is optimised so that the hairs are close enough so as to not penetrate the water’s surface during impact, but not so close together it becomes inefficient.
“More densely packed setae will definitely cost more biological energy, and increase the adhesion and energy dissipation during the movement of water striders on water,” Duan says.
The spacing is designed to maximise the supporting force provided by the water surface tension which creates a meniscus — a curved surface of water — in between each individual hair. It is also designed so the water doesn’t cling to the hair, enabling the water strider to move quickly and easily across the water surface.
“For insects living on water, low energy dissipation is needed for them to lift their legs from water so they can quickly move and flee away from possible threats,” the researchers’ write.
“During a lifting process, the convex contour enables the detaching of the contact menisci to happen gradually from both sides of a hairy surface instead of the simultaneous detachment of all the menisci, which will greatly reduce the force and energy needed to lift a hairy surface from water.”
The researchers also found thicker hairs have greater load-carrying capacity as compared to thin hairs.
The ability of deep sea fish to plumb new depths may be constrained by biochemistry, new research by an international team has found.
This photo of hadal snailfish (Pseudoliparis amblystomopsis), snapped at 7500 metres down, is the second deepest observation of a live fish.
The research, published today in the Proceedings of the National Academy of Sciences, explains why there are no known fish species below 8400 metres, despite the presence of other marine animals such as anemones, crustaceans and sea cucumbers.
Based on previous work, the researchers, led by biologist Professor Paul Yancey from Whitman College, Washington believed that the depth limits of fish were related to levels of osmolytes present in their bodies.
Osmolytes are soluble organic compounds that counteract the effects of pressure on proteins by altering water structure so that the tendency for pressure to force water molecules into the interior of cells is reduced and the cells can keep functioning.
Gelatinous texture
To test their theory, the researchers captured five specimens of the second deepest known fish, the hadal snailfish (Notoliparis kermadecensis), from a depth of 7000 metres in the Kermadec Trench to the north east of New Zealand.
“The Kermadec Trench is one of the deepest in the world, and no hadal snailfish had been caught there since the 1950s,” says Dr Ashley Rowden from the National Institute of Water and Atmospheric Research in Wellington, New Zealand, who was part the study team.
The fish were captured from a 28-metre boat and bringing them to the surface took more than three hours in rough seas, requiring determination and strong stomachs from those on board.
“Out of their natural environment, snail fish feel like water-filled condoms,” says Rowden. “Like other fish from the deepest hadal zone [region below 6000 metres] their gelatinous texture is an adaptation to extreme pressure (around 10Mpa or 1000 times the surface atmospheric pressure).”
“They are relatively delicate organisms and don’t survive the journey to the surface, possibly due to the pressure changes they experience as they journey up from 7000 metres below,” Rowden says.
Osmolyte levels
Once back on dry land, the researchers compared the levels of the osmolyte trimethylamine N-oxide (TMAO) in the hadal snailfish with that in other bony fishes from a range of bathymetric zones in the ocean.
The concentration of TMAO present in the muscle tissue of the snailfish was significantly higher than for fish living at shallower depths.
When they extrapolated their findings, the researchers found that it is unlikely that bony fish could survive below 8,200 metres, because the high concentrations of TMAO that would be required to combat the effects of pressure can also reverse cellular osmosis gradients — the difference between the salinity levels inside and outside the cells.
“Other research has shown a general increase in TMAO levels from shallow water dwellers to fish living at 5000 metres,” Rowden adds.
“The snailfish came from 2000 metres below where previous samples had been taken, and represented a big jump in TMAO levels.”
Early days
Bony fish are one of the largest animal groups on Earth and have exploited most available habitats, Rowden explains.
“There is the potential for organisms to get to every corner of the world’s environment, but the deepest oceans are yet to be colonised by bony fish.
“This research indicates that they are biochemically constrained from inhabiting the deepest parts of the ocean, but as deep-sea fish evolved only relatively recently, geologically speaking, over time they may evolve further adaptations to cope with the unique demands of the hadal environment.”
Size differences among fish and competition for breeding space lead to the formation of new species, according to a new study by researchers from the University of Bristol published today in Nature Communications.
The cichlid fish Telmatochromis temporalis is found in Lake Tanganyika in East Africa
Competition may play an important role during the evolution of new species, but empirical evidence for this is scarce, despite being implicit in Charles Darwin’s work and support from theoretical studies.
Dr Martin Genner from Bristol’s School of Biological Sciences and colleagues used population genetics and experimental evidence to demonstrate a role for competition that leads to the differentiation of new species within the highly diverse cichlid fishes of Lake Tanganyika in East Africa.
They found that the cichlid fish Telmatochromis temporalis shows two genetically distinct ecomorphs (local varieties of a species whose appearance is determined by its ecological environment), that strongly differ in body size and the habitat in which they live.
Dr Genner said: “We found large-sized individuals living along the rocky shoreline of Lake Tanganyika and, in the vicinity of these shores, we found small-sized individuals, roughly half the size of the large ones, that live and breed in accumulations of empty snail shells found on sand.”
According to the study, the bigger fish outcompete the smaller ones, driving them away from the preferred rocky habitats and into the neighbouring sand, where the smaller fish find shelter for themselves and their eggs in empty snail shells.
“In effect, big and small fish use different habitats; and because of this habitat segregation, fish usually mate with individuals of similar size. There is virtually no genetic exchange between the large- and small-bodied ectomorphs,” Dr Genner commented.
Speciation occurs when genetic differences between groups of individuals accumulate over time. In the case of Telmatochromis there are no obvious obstacles to the movement and interaction of individuals. But, the non-random mating between large- and small-bodied fish sets the stage for the evolutionary play.
Dr Genner said: “The relevance of our work is that it provides experimental evidence that competition for space drives differential mating in cichlid fish and, in time, leads to the formation of new species. Nature has its ways – from body size differences to the formation of new species. And clearly, size does matters for Telmatochromis and for fish diversity.”
The study was carried out by evolutionary biologists from the University of Bristol, the Natural History Museum London, the University of Kyoto and the Natural History Museum in Bern.
Reference
‘Competition-driven speciation in cichlid fish’ by Kai Winkelmann, Martin J. Genner, Tetsumi Takahashi and Lukas Rüber in Nature Communications
A fish with an unusual addiction to prawn cocktail crisps has been put on a healthier diet after turning a shade of pink.
Chip addict: If you see this fish, don’t give her any Skips. Photo: Sea Life London aquarium
The Giant Gourami is being weaned off her favourite Skips snack by staff at the Sea Life London aquarium.
Aquarists at the centre were baffled by the 40cm fish’s refusal to feed until they learned of its previous unorthodox diet.
‘I have never heard of a fish being fed crisps,’ said curator Jamie Oliver.
‘Gouramis usually eat a diet of fruit and vegetation but fortunately Gerty doesn’t appear to have suffered any ill effects from her unhealthy addiction.
‘However, we would not recommend feeding fish crisps of any kind.’
He added: ‘We’re delighted we could find a home for Gerty but her case just goes to show how important it is to be responsible when buying creatures for home aquaria.’
The Sea Life London aquarium support the Big Fish Campaign which aims to raise awareness about the problem of aquarium fish growing too large for standard-sized home aquariums.
On the prowl: ‘Hey, you, gimme some more chips, pronto Photo: Sea Life London aquarium
Lowly bottom-feeders survived the biggest mass extinction in history, according to a study by scientists at the University of Plymouth.
Hippocardia cunea: Rostroconchs are the only class of mollusks in the fossil record that are extinct today. They lived from the Early Cambrian until Late Permian as marine filter feeders partially buried in sediment. Source: Falls of the Ohio State Park
Lowly bottom-feeders survived the biggest mass extinction in history to rescue life in the world’s oceans, a UK study has found.
Globally, the Late Permian extinction 252 million years ago wiped out 90 per cent of all marine species but creatures living on the sea floor fared better with almost 40 per cent surviving.
Scientists at the University of Plymouth made the discovery after compiling a database of 22,263 individual fossil marine invertebrates belonging to 1770 families of organisms.
The researchers worked out how each species moved, fed, and affected the ecosystem.
They learned that after the extinction, driven by volcanic eruptions and climate change, 38 per cent of benthic – or sea floor – life survived.
“Crucially, not one of the key ecological groups of animals that lived on or within the sea floor, and which keep ecosystems functioning, were completely eliminated,” said lead scientist Professor Richard Twitchett.
Colleague William Foster said: “The fact that none of the key benthic ecological groups were completely eliminated globally during the biggest known extinction recorded in the fossil record was unexpected and demonstrates a certain level of resilience that had not been appreciated before.”
The findings reported in the journal Nature Geoscience may help scientists better understand the fate of life in the oceans as a result of climate change today.
“We might predict that the present changes will not cause complete elimination of these key functional groups, unless future extinctions turn out to be more severe than that experienced 252 million years ago,” said Mr Foster.
“However, our results also clearly show that some ecosystems do completely collapse, especially tropical ecosystems, in particular reefs.”
Prof Twitchett said: “In this case, the global oceans in the extinction aftermath were a bit like a ship manned by a skeleton crew: all stations were operational but manned by relatively few species.”
Sometimes in research the answer is right under your nose.
The humble fishing line. Photo: Flickr/derfian
In our case, we spent nearly two decades developing exotic materials as artificial muscles – to now show in a paper published in Science today that the best performing systems can be made from ordinary, everyday fishing line.
Or sewing thread, if you prefer.
Not only are these materials cheap and readily available, they can be converted into high performance artificial muscles easily – just start twisting!
Polymer coil muscles.
We attached one end of the fishing line to an electric drill and hung a weight off the other to apply some tension. We stopped the weight from rotating as we used the drill to twist the fibre.
At first the twisted fibre shortened but maintained a uniform shape. But at a critical point, a loop or coil formed in the fibre and further twisting produced more coils. Before too long the whole fibre was a spring-like coil.
To set this shape we applied a little bit of heat using a hairdryer and let it cool. If we then hung a weight off the polymer coil and applied some more heat, the coil contracted.
For more convenience and better temperature control, we wrapped a conductive material around the fibre and applied heat by passing a current.
Muscle-like performance
The amount of contraction and the force generated can be impressive and in most respects compare favourably with our own muscle.
In one example, we used a 16cm length of coiled Nylon-6 fishing line 0.86mm in diameter to lift a 500g weight about 20mm in 2 seconds.
A similar sized natural muscle would also contract about 20mm in slightly shorter time (~1 second) but lifting only 150g.
Comparing ‘muscles’ made by coiling (from top to bottom) 2.45mm, 0.86mm, 0.28mm and 0.15mm Nylon-6 monofilament fibres. Photo: Science/AAAS
By optimising our coil structures we can easily achieve 50% or more contraction in length and increase contraction speed to 7.5Hz.
Our polymer coil muscles also last a long time – we gave up testing after 1.2 million cycles where the muscle reversibly contracted 10% in length in 1 second per cycle.
Power textiles
One application that we are pursuing with the polymer coil muscles is in our massage sleeve designed to reduce the effects of lymphoedema, a condition that affects around a third of women diagnosed with invasive breast cancer.
Lymph sleeve animation.
Breast cancer‐related lymphoedema (BCRL) is the swelling of the arm caused by the build-up of lymphatic fluids and leads to heaviness, swelling and discomfort for patients.
Massage is an effective treatment and the “lymph sleeve” is meant to be worn by BCRL patients during their daily lives. The lightweight actuating fabric will detect swelling and then respond by “squeezing” the arm to enhance lymph flow.
A twisty tale
The discovery of the polymer coil muscles is the outcome of more than five years of collaborative effort from researchers around the world.
The work started with the discovery by University of Wollongong PhD student (and now ARC Discovery Early Career Researcher Award Fellow) Javad Foroughi of a “torsional” type of actuation movement in electrochemically charged carbon nanotube yarns.
Subsequently, our collaborators at the University of Texas at Dallas (UTD) – who make the yarns – also found that similar torsional actuation response could be produced by filling the yarn pore volume with candle wax to make hybrid yarn muscles.
Heating the wax generated the torsional or twisting movement. It was also observed that overtwisting these yarns generated coils and that these coils contracted by up to 10% in length when the wax was heated.
Old theories still help
At that stage we did not know why the coiling amplified the length-wise tensile actuation.
But our most recent collaboration has revealed more on the coupling between the torsion and the coil contraction by applying the mechanics theory that had been developed for more than a century and applied to helically-coiled springs.
Finally, we also discovered that similar effects occur in highly oriented polymer fibres when they are twisted into coils.
The pathway to discovery was by no means obvious. If we had not been investigating exotic materials – such as carbon nanotubes – then we would not have observed the very large torsional actuation in these materials.
That work led us to investigate further the effect of twist and the discovery of overtwist-induced coiling. From there we were able to produce high performing contractile muscles from both overtwisted carbon nanotube yarns, and more recently, ordinary polymer fibres like fishing line.
What’s next?
While it’s impossible to predict what the next breakthrough will be, we do know the areas where improvements are needed.
Efficiency is well below that of muscle. Approximately 20% of the input chemical energy for muscle is converted to mechanical work.
Our muscles convert about 2% of electrical heat energy to muscle work, similar to shape memory alloys.
We would also like to use stimuli other than heat and our preliminary work has shown that movement is possible with light or chemical agents.
Geoff Spinks receives funding from the Australian Research Council.
Evolution of life on Earth began about 3.5 billion years ago but it has not been a constant or continuous process.
Slime on Earth… that’s all there was for a billion years. Photo: www.shutterstock.com
During the middle years of Earth’s history (1.8 billion to 800 million years ago), evolution stagnated. Life remained as little more than a layer of slime for a billion years. This period has become known as the “boring billion” years.
So what was going on? A research team led by geologists at the University of Tasmania has developed new mineral technology to track the trace metal content of the ocean and oxygen content of the atmosphere over the past 3.5 billion years. This has never been achieved before.
Why is it important? Evolution of life in the oceans is strongly influenced by trace metals, as many metals (such as copper, zinc, cobalt and selenium) are taken up by marine species and are critical for life and evolutionary change.
Studying the ocean floor
Our UTAS research team – of which I was a part – with help from many other international geologists, have been collecting seafloor sediments from all around the world over the past six years.
Ross Large and Valeriy Maslennikov (from the Russian Academy of Science) on location in Siberia. Photo: Ross Large
We found pyrite (iron sulfide) in each sample and analysed for 22 different trace metals with a cutting edge laser system at UTAS, and built a unique database of more than 3,000 pyrite laser analyses to track changes in ocean chemistry spanning a 3.5-billion-year period through time.
Some exciting and totally unexpected outcomes emerged from this ocean tracking technology. The most significant outcome relates to how trace metals in the oceans have influenced the evolution of life.
Back in the early part of Earth’s history, from 3.5 billion to 1.8 billion years ago, single celled life evolved slowly but progressively, related to an abundance of available trace metals in the oceans. But during the “boring billion”, from 1,800 million to 800 million years ago, evolution slowed. This has been a puzzle to scientists.
Ocean life nearly collapsed
Our research, published in the Earth and Planetary Science Letters, suggests that the reason for the slow down is that the trace metal content of the oceans declined. This resulted in a depletion of critical trace metal nutrients to the point that oxygen content dropped and life in the oceans was in great danger of total collapse.
But rather than causing a mass extinction, marine life and evolutionary change was put on hold for a billion years.
Following the boring billion, our research shows that the trace metal content in the oceans rose steeply in a series of steps over a 200-million-year period, from 750 million to 550 million years ago.
This was accompanied by a steep rise in oxygen in the atmosphere (known as a Great Oxidation Event, see below) that led to the Cambrian explosion of life and progressive evolution to the present time.
The essential trace elements
Bio-essential trace elements are critical to life and evolution. These include cobalt, selenium, copper, zinc, molybdenum, vanadium and cadmium. Certain species need these trace elements to survive.
The elements are linked into the chemical structure of the cells and become a natural nutrient for survival. Cobalt is a central atom in the structure of vitamin B12, whereas zinc is essential for growth in many species.
The UTAS research team showed that at certain periods of earth history these trace elements were in short supply (such as the boring billion period) leading to evolutionary decline, whereas in other periods the bio-essential elements were in great abundance, causing rapid evolutionary change.
The Cambrian Explosion
The Cambrian explosion was the relatively rapid appearance, around 542 million years ago, of most major animal phyla, as demonstrated in the fossil record.
Fossil tracks form the Cambrian explosion. Photo: Flickr/Maitri
This was accompanied by major diversification of other organisms. Before about 580 million years ago, most organisms were simple, composed of individual cells occasionally organised into colonies.
Over the following 70 million or 80 million years, the rate of evolution accelerated by an order of magnitude and the diversity of life began to resemble that of today.
The Cambrian explosion has generated intense scientific debate. The seemingly rapid appearance of fossils in the “Primordial Strata” was noted as early as the 1840s. In 1859 Charles Darwin discussed it as one of the main objections that could be made against his theory of evolution by natural selection.
The long-running puzzlement about the seemingly abrupt appearance of the Cambrian fauna 540 million years ago centres on three key questions:
was there really a mass diversification of complex organisms over a relatively short period of time during the early Cambrian, and are we lacking evidence of what really happened?
what might have driven such rapid change – was it all due to rising oxygen?
implications about the origin and evolution of animals?
This latest research by the UTAS team demonstrates, for the first time, a rapid increase in bio-essential trace elements in the ocean starting 660 million years ago. So was this the cause of the Cambrian explosion of life?
Great Oxidation Events (GOEs)
GOEs are large increases in oxygen in the Earth’s atmosphere and there have been two in Earth’s history – one at 2.4 billion to 2.5 billion years ago and one at around 700 million to 550 million years ago corresponding with the Cambrian Explosion.
There are several schools of thought about GOEs’ origin. The most favoured theory is that the GOEs are produced by a dramatic increase in ancient marine organisms (cyanobacteria) that released oxygen as a by-product of photosynthesis.
But which came first? Did the increase in oxygen speed up evolution of life or did an increase in life result in a rapid rise in atmosphere oxygen?
Either way, the oxygen did eventually accumulate in the atmosphere, providing a new opportunity for biological diversification as well as tremendous changes in the nature of chemical interactions between the atmosphere, rocks, oceans and living organisms.
The research team at UTAS, using a novel approach to the problem, demonstrated major changes in trace element concentrations in the ocean at both GOEs, which may be the answer to the rapid expansion of life.
This is the start of a new journey for the Tasmanian research team and we will be doing much more with this technology.
But it’s already becoming clear that there have been many fluctuations in trace metal levels over the millennia and these may help us understand a host of events including the emergence of life, fish, plants and dinosaurs, mass extinctions, and the development of seafloor gold and other ore deposits.
Ross Large receives funding from Australian Research Council and Australian Mineral Industry Research Association.
A thought provoking perspective of the world from XKCD
This comic shows estimated average frequency. I wanted to include the pitch drop experiment, but it turns out the gif format has some issues with decade-long loops. Source XKCD
Lets face it – without a face no-one would recognise us, nor would we be able to guess what others might be thinking or feeling.
We have fish to thank for the makeup of our face. Photo: Flickr/Ben Shepherd
Faces and their subtle degrees of symmetry and expression have defined human beauty and tragedy throughout past millennia of art and drama.
Faces, though, are not uniquely human, but are a shared feature with all back-boned animals (vertebrates), from sharks to squirrels. So when and where did the face first acquire its modern, recognisable shape?
A paper published today in Nature announced that the face had its origins deep within extinct armoured fishes called placoderms.
We are all derived from placoderms
Placoderms were really gnarly armoured fishes that ruled the oceans, rivers and lakes of the world from about 440-360 million years ago. They were the first animals to evolve jaws and teeth, a truly landmark event in evolution that denotes the beginning of the lineage leading to sharks, bony fishes, amphibians, reptiles and mammals.
Indeed much of the human body plan took shape from these armour-plated fishes. Placoderms have given us many evolutionary legacies including paired hind limbs, mating by copulation, paired bony plates forming the skull, and even the modern inner ear with three semicircular canals.
A new study by a team of French and Swedish scientists led by Dr Vincent Dupret, of the University of Uppsala, now builds upon recent work published in late 2013 in Nature on a “missing link” placoderm fish from China called Entelognathus.
This was the first creature to have evolved a suite of bony upper and lower jaw bones similar to those in tetrapods, four legged animals like reptiles and mammals. This spectacular fossil fish rooted placoderms firmly at the base of the tree containing all higher vertebrates, including us.
An old fossil revealed by new technology
The new paper takes the evolutionary story a big step further back to an even more primitive placoderm, named Romundina. This fish was discovered in the early 1970s from an island in Arctic Canada and the 2-3cm long skulls were prepared out of the limestone rock using dilute formic acid to dissolve the rock away.
First studied and named in 1975 by Norwegan palaeontologist Tor Ørvig (1916-1994), Romundina was one of the first examples of a very well-preserved 3D early placoderm fossil. It has been used in many studies of early vertebrate evolution, but up until now the detailed internal cranial anatomy remained unknown.
“The tiny skull of the 400 million year old placoderm fish Romundina, from the left side view. Actual size about 3 cm long. Photo: Philippe Loubry, MNHN-CNRS-UPMC Paris6
Dr Dupret told me he began the work to get practise working with 3D scanning software and the more he delved into the tiny skull’s anatomy the more interesting it became.
“Watching the complete 3D model of this tiny fossil with all structures reconstructed – the nerves, blood vessels, and so on – is a big thing,” Dr Dupret said.
“But then realising that it is like watching a ‘mirror to the past’, staring back at you, with some structures close to ours, while other are closer to jawless vertebrates, is a little like Prince Hamlet looking at Yorick’s skull!”
Using advanced synchrotron imaging, the delicate 3D skull of this fish readily gave up its innermost anatomical secrets to the intense beam from the European synchrotron in Grenoble. The results are breathtaking for any biologist: a detailed 3D map of the cranial cavities revealing how the brain, sensory structures,nerves and arteries were positioned and proportioned.
A synchrotron tomography movie showing the internal anatomy of the 400 million year placoderm Romundina. The outer bone dissolves away to reveal the reconstructed shape of the brain, nerves and circulatory system. Dr Vincet Dupret, University of Uppsala.
How placoderms gave us the modern vertebrate face
The new work found that the internal skull anatomy of the fish retained a number of primitive characteristics found only in jawless fishes, such as the lamprey and a number of extinct fossil forms.
The short nasal capsules situated between the eyes is such an example, as in later placoderms and all subsequent animals, the nose develops in front of the face. But what enabled the paired nasal capsules to move out to the front of the skull?
The study suggest that inside the head of Romundina an area of tissue developed from the braincase into a flat platform formed by cartilages called trabeculae. These first evolved in ancient armoured jawless fishes such as Shuyu but are more extensively developed in Romundina.
They give support to the front part of the brain (telencephalon) as it extended forwards to grow into large paired nasal capsules. This would have enabled fishes, and all later vertebrates, to develop a keen sense of smell, a necessary ability to help find prey and sense predators.
A synchrotron tomography movie showing the internal anatomy of the 400 million year placoderm Romundina. The outer bone dissolves away to reveal the reconstructed shape of the brain, nerves and circulatory system. Photo: Dr Vincet Dupret, University of Uppsala.
Beauty is often talked about in terms of symmetry and placement of human facial features. A beautiful face is one of perfect symmetry.
Just imagine then if our faces hadn’t evolved further from the Romundina condition. We would have our nostrils opening between our eyes.
After Romundina, placoderms developed proper noses with paired nostrils opening from a snout protruding in front of the eyes. In later placoderms, such as Entelognathus, the mouth become covered with an outer row of flat bones which then fixed the position of eyes, nose and mouth within the vertebrate skull from this point onwards.
A simplified version of face evolution, from jawless lampreys through to tetrapods (the human). The two critical stages in developing a truly recognisable, modern facial pattern occur within placoderms such as Romundina and the arthrodire Compagopiscis (centre). Image: Image of the placoderm, John Long
A simplified version of face evolution, from jawless lampreys through to tetrapods (the human). The two critical stages in developing a truly recognisable, modern facial pattern occur within placoderms such as Romundina and the arthrodire Compagopiscis (centre). Image of the placoderm, John Long
A bone of contention
The new paper presents one result that not all palaeontologist will agree with. The phylogenetic analysis, showing the relationships of the various placoderm groups, presents a radical hypothesis about the sequence of character acquisition in the group. Every major paper on the subject in the past five years in Nature gives a completely different result of the relationships of the various placoderm families.
To me this suggests that much further work needs to be done to resolve the relationships of these placoderm groups. This is important work as it will give us a better understanding of the timing and sequence of appearance for the facial and other characters in the grand narrative of modern vertebrate evolution.
Fortunately Australia has some of the world’s best fossil sites of this age at Gogo in the Kimberely, and Taemas-Wee jasper in NSW. We have several new, spectacular placoderm skulls preserved in 3D that my colleagues and I are currently working on using microCT and synchrotron imaging. We hope these discoveries will help resolve some of these critical issues in evolution.
Charles Darwin’s book on The Expression of the Emotions in Man and Animals (1872) first announced that our facial expression are not unique to humans, but are a shared trait within the animal kingdom.
From today’s paper we now know that the origin of the face, at least in terms of the symmetry and placement of eyes, nose and mouth, is another hallmark feature that first evolved in ancient placoderms, now passed on to us humans, through the gift of evolution.
John Long receives funding from the Australian Research Council.
It’s jellyfish mania in Australia right now, thanks to our snotastic new friend, whose discovery on a Tasmanian beach was announced just last week. While Captain Vom waits patiently for his new official name, we’ve got time to welcome another Australian jellyfish species into the spotlight, and this one’s been waiting more than a century for its fifteen minutes.
Crambione cookii with its fish friends. Photo: Puk Scivyer
Meet Crambione cookii: a species that was discovered in the 1890s off the coast of Cookstown in Queensland and then not seen again for more than a hundred years. Well, that was how the story went, so when Puk Scivyer from Underwater World on the [Gold] Sunshine Coast photographed a dead specimen in 1999, she knew she was on to something pretty special. Especially since there were no photographs of the species on record – just a single sketch from the original discovery.
She sent the photograph to CSIRO marine biologist and Australia’s foremost authority on everything jellies, Lisa-Anne Gershwin, and in 2010, Gershwin published the discovery. The first confirmed sighting of the species in more than 100 years.
C. cookii is about 50 cm across the dome and about that long vertically. It’s got a light, pinkish hue, and a mass of thick, frilly tentacles. “It looks like a cauliflower with legs,” says Scivyer.
Things got spooky when late last year, Scivyer picked up another C. cookii, and this time, she’d caught a live one. “We were out on our boat, releasing turtles on that particular day, when I saw a rather large jelly in the water that didn’t look like the ones we normally encounter. We were in the process of setting up a jellyfish exhibit, so maybe our eyes were open a bit more than usual,” says Sciyver.
She sent Gershwin some footage of her find. “She said, ‘I think this is Crambione cookii. What do you think?’ And I looked at it and went, ‘Oh my God. You’ve got to be kidding. What are the odds? Because at that time we thought that it was an incredibly, incredibly rare species, and the only two sightings in 100 years were by the same person.”
Coincidence? Kind of, but only in the sense that Scivyer was the one qualified person to come across the species twice in over a century. It turns out that plenty of people had seen the species since its original discovery, and sure enough, once they knew it was special, the photographs started to pour in.
“It was pretty exciting. It’s just that it escaped the scientific community’s eyes for 100 years, but now that it’s been seen, members of the public have been contacting us with pictures,” says Scivyer. “So it’s not like it’s the last single jelly in the world, it’s just that nobody had really been in a position to find it when they knew that it was something unusual. They’re not rare, it’s more that they’re rarely encountered.”
When Scivyer pulled C. cookii out of the ocean, she noticed that nine fish seemed to be living amongst its tentacles. She scooped them up and they were housed together in a special jelly tank at Underwater World. And then, as if from nowhere, fish emerged from all over the place.
Crambione cookii in its Underwater World tank. Photo: Puk Scivyer.
“It was just a weirdest thing,” says Gershwin. “When [Scivyer] caught the specimen and let it go in the aquarium, I think it originally had nine fish with it. She sent me video with the nine fish and she was so excited. And then the next day she sent me more video and it’s got 25 or 30 fish. And then the next day she sent me more video and it’s got like 50 fish. It was unbelievable.”
“That’s probably what we found most interesting about him,” says Scivyer. “This single jelly had a population of 76 fish and several crustaceans living with him. The fish were actually nestling the jelly. Up until now it’s always been thought that they didn’t make contact with the jelly to avoid being stung, but from everything we’ve seen, they actually physically nestle in it, and they’re not the species of fish that would normally be known to do that, like clown fish with anemones. But these were trevally, [a species] never known to [associate so closely with jellies].”
Scivyer counted at least three different species of fish that were living with the jellyfish. She thinks they might have been feeding on the parasitic crustaceans that had attached themselves to its tentacles.
While it’s clear from the number of sightings by members of the public thatCrambione cookii is not rare, and possibly not even particularly uncommon, figuring out its population density and range is a particularly difficult task.
“With most jellyfish blooms, it comes and goes, sometimes within 24 hours. You can never quite pick when they’re going to happen,” says Scivyer. “We’re kind of getting an indication that it’s this time of the year [December], because it’s coming into our summer period, and we haven’t had any pictures from in the middle of winter. But that could be because people are out of the water when it’s rather cold. We’re also getting pictures distributed up the east coast of Australia. It’s a rather extensive range compared to what we thought originally.”
http://www.youtube.com/watch?v=Oq8hNS9dWIE
And finally, the million-dollar question – just how powerful is that sting?
“I would say moderate,” says Scivyer. “I haven’t physically made contact with the tentacles, but I did happen to touch the water that he’s been in, and it feels like a decent whack on the hand. You can definitely feel it in the water. It’s quite common for jellyfish, a lot of people when they’re in the water, they get the little stingy bits on them, quite often they’re just the stinging cells of the jellyfish.”
“Oh it stings. It hurts,” says Gershwin. “It’s not life threatening or anything like that. But it will get your attention. I think maybe it’s kind of like a Lion’s Mane or a Snotty, so it’s pretty zappy, but then it goes away. It makes you wonder, certainly it must be stinging these fish, but then to have the fish sheltering inside it, you’ve got to sort to say, well no, it can’t possibly be stinging the fish, or they’d be dead.”
Unfortunately the jellyfish didn’t last too long in captivity, but judging from the size of it – the original specimen from the 1980s was just 10 cm across the dome – it was probably fairly old when it was picked up. It now resides in the Queensland Museum as a specimen for future studies.
I’d just like to point out that the Daily Mail called Crambione cookii “deadly”, “incredibly rare”, and said that “Ms Scivyer thinks it is unlikely that any more will be found”. Gizmodo called it “deadly” too. Guys, come on. Thanks for ruining itsWikipedia page.
