Bizarre 'gunslinger' octopus caught for first time

For the first time, the tiny male of a bizarre species of octopus, which carries a slew of stinging weapons and is 100 times smaller than its females, has been captured alive by Australian scientists off the Great Barrier Reef.

The find was made by a group of scientists from the universities of Melbourne, Tasmania and Leeds, during a 'blackwater hang' - a night dive suspended in deep water. The discovery is described in the latest issue of the New Zealand Journal of Marine and Freshwater Research.

"You always hope you might bump into something like this," said Dr Mark Norman, an honorary fellow at the department of zoology at the University of Melbourne. "The chance is infinitesimally small."

Dead males have been found in trawls and plankton nets before, but this is the first time a live one has been seen. Known as the blanket octopus, or Tremoctopus violaceus Chiaie, it spends its entire life cycle in the open ocean, so either sex is rarely encountered.

"We know so little about the sea," Norman told ABC Science Online. "These are one of those almost mythical creatures of the sea. For us, it's as exciting as swimming with a giant squid."

While other octopus species also have size differences between the sexes - known as sexual size-dimorphism - the blanket octopus is the most extreme example known. The male specimen discovered is 2.4 cm long, weighing just 0.25 kg. Mature females have been measured at 2 m in length, weighing about 10 kg.

The male seems to have adapted to his small size, having a comparatively large eye which could help in locating females. Being small may also mean that they take less time to mature.

But for the male, sex is a one-off and probably fatal affair. They allocate one of their arms to reproduction, keeping it in a pouch in the centre of their tentacles. When they mate, the pouch ruptures, sperm is injected into the tip of the modified arm, which is then severed and passed to the female.

Thereafter, the male then almost certainly dies, while his detached arm remains in the female's mantle cavity until it is used to fertilise her eggs. Females are often found with several arms in their cavity, indicating competition amongst males.

The scientists have never found a dead male with a new arm, suggesting that they die after mating. Other octopuses are known to be able to drop off their arms as decoys to predators, in the same way that some lizards lose their tails. Arms tend to grow back in six to eight weeks.

But the blanket octopus' kamikaze approach to fertilisation - shedding an arm that keeps living when the rest of the animal dies - is only found in a couple of other octopuses, said Norman. "It looks like the arms do live for a long time [inside] the females."

The small size of the male may be an adaptation for self protection. Male and immature female blanket octopuses arm themselves with weapons snatched from competitors, taking stinging tentacles from the Portuguese man-of-war jellyfish and holding them in the suckers of two pairs of their upper arms - like a gunslinger with a pair of revolvers.

When threatened, they pull their arms over their bodies and expose the stinging tentacles. 

But this only works if the octopus is small and would probably not be enough to protect a large mature female: no female longer than 7 cm has been observed to carry the tentacles. Scientists speculate that the bigger suckers in the mature animal may not be able to hold the tentacles without stinging themselves. http://www.abc.net.au/science/news/stories/2003/776877.htm

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Toxic sea

Analysis of a 380-million-year-old crab-like fossil from Western Australia has painted a gruesome picture of the events leading to one of Earth's major mass extinctions.

Climate change and a devastating meteorite have both been fingered as causes for the decimation of marine life during the late Devonian period.

But research published in a recent issue of the journal Geology suggests the extinction occurred as a result of a toxic ocean, devoid of oxygen.

"We think there was anoxia, where toxic levels of hydrogen sulfide are released into the zone where light penetrates into the ocean," says organic geochemist Professor Kliti Grice, of Curtin University.

"A modern analogue of the conditions that existed at this time is the Black Sea."

Grice and colleagues, including PhD student Ines Melendez, reached their conclusions after analysing a 380 million-year-old crab-like fossil from the Gogo Formation in Canning Basin, Western Australia.

They identified chemical remains of various biological molecules, known as biomarkers, that helped paint a picture of environmental conditions at the time.

The researchers found a derivative of cholesterol, confirming for the first time that the fossil was the remains of a crustacean.

And they found biomarkers of photosynthesising phytoplankton, which the crustacean would have fed on.

Grice and colleagues also found biomarkers of green sulfur bacteria, also called Chlorobi which would have photosynthesised using hydrogen sulfide instead of water.

She says Chlorobi made a special pigment that enabled them to capture light of longer wavelengths, making it possible from them to survive in the murky waters beneath the bloom of phytoplankton.

"The ocean became stratified with an oxygen layer and an anoxic layer, and where the Chlorobi lived, right at the point where hydrogen sulfide is abundant," says Grice.

Last but not least, the researchers found biomarkers of sulfate-reducing bacteria, which would have lived even deeper down in the ocean and survived by degrading organic matter using sulfate instead of oxygen. This would have been the original source of the hydrogen sulfide on which the Chloribi thrived.

Grice says the condition of the ocean was identical to that which occurred during a later mass extinction at the end of the Permian, the largest extinction event in the past 600 million years.

The crustacean may have sunk to its death at the bottom of the ocean, intoxicated by hydrogen sulphide, says Grice, where it was preserved for hundreds of millions of years.

Preservation

The researchers say the 15-centimetre wide crustacean was exceptionally well preserved by a combination of processes.

Grice says the hydrogen sulphide chemically preserved the muscle tissue in the crustacean, as well as organic molecules from the green sulfur bacteria.

"The molecules and the fossil were all preserved by the same mechanism, and that has never been reported in such detail," says Grice.

The fossil was further preserved by a calcium carbonate encasement built by the sulfate-reducing bacteria.

The levels of biomarkers from sulfate-reducing bacteria were particularly high in this encasement, Grice says.

The research was funded by the Australian Research Council. http://www.abc.net.au/science/articles/2012/11/14/3632446.htm

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Fish tails

Fish tails stir up world's oceans

Creatures large and small may play an unsuspectedly important role in the stirring of ocean waters, according to a study.

So-called ocean mixing entails the transfer of cold and warm waters between the equator and poles, as well as between the icy, nutrient-rich depths and the sun-soaked top layer.

It plays a crucial part in marine biodiversity and, scientists now suspect, in maintaining earth's climate.

The research is published in today's edition of the journal Nature.

The notion that fish and other sea swimmers might somehow contribute significantly to currents as they move forward was first proposed in the mid-1950s by Charles Darwin, grandson of the legendary evolutionary biologist of the same name.

But this was dismissed by modern scientists as a fishy story.

In the 1960s, experiments compared the wake turbulence created by sea creatures with overall ocean turbulence.

They showed that the whirls kicked up by microscopic plankton or even fish quickly dissipated in dense, viscous water.

On this evidence, sea creatures seemed to contribute nothing to ocean mixing.

The clear conclusion was that the only drivers of note were shifting winds and tides, tied to the gravitational tug-of-war within our solar system.

Old theory re-established

But the new study by Kakani Katija and Joan Dabiri, of the California Institute of Technology, goes a long way toward reviving the 20th century Darwinian view, and uses the quiet pulse of jellyfish to prove the case.

Katija and Dabiri devised a laser-based system for measuring the movement of liquid.

They donned scuba gear and then released dye in the path of a swarm of jellyfish in a saltwater lake on the Pacific island of Palau.

The video images they captured showed a remarkable amount of cold water followed the jellyfish as they moved vertically, from deeper chillier waters toward the warmer layers of the surface.

Katija and Dabiri say the 1960s investigators had simply been looking in the wrong place.

They had been on the alert for waves or eddies - signs that the sea was being stirred up in the creatures' wake - rather than vertical displacement of water.

What determines the amount of water that is mixed is the size and shape of the animal, its population and migratory patterns.

Influence on climate

Churning of the seas is a factor in the carbon cycle.

At the surface, plankton gobble up carbon dioxide (CO2) through photosynthesis.

When they die, their carbon-rich remains may fall gently to the ocean floor, effectively storing the CO2 for millennia - or, alternatively, may be brought back to upper layers by sea currents.

William Dewar of Florida State University in a commentary, also published in Nature, says the new paper challenges conventional thinking.

"Should the overall idea of significant biogenic mixing survive detailed scrutiny, climate science will have experienced a paradigm shift," he says.

http://www.abc.net.au/science/articles/2009/07/30/2640838.htm

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Earliest animals flexed their muscles

A group of British and Canadian palaeontologists have found fossils that show the earliest evidence of animal locomotion.

The team from the University of Oxford and Memorial University of Newfoundland, found fossilised trails left by Ediacarans, an enigmatic assemblage of soft-bodied creatures that lived 30 million years before modern animals evolved.

The find, in 565 million-year-old rocks at Mistaken Point in Newfoundland, Canada, appears in the current issue of the journal Geology.

The discovery of 70 fossilised trails, each about 5 to 17 centimetres long, is comparable to the kinds of marks left in the sea floor by modern animals like sea anemones, the researchers say.

Although they can't pin the trails to a specific creature, the discovery shows at least some of the Ediacarans were mobile, and hence must have had muscles.

Similarities in the trails to the modern-day anemone Urticina suggest the organisms that left the fossil traces may have had a muscular 'foot', the researchers say.

"This is exciting because it is the first evidence that creatures from this early period of Earth's history had muscles to allow them to move around, enabling them to hunt for food or escape adverse local conditions and, importantly, indicating that they were probably animals," says University of Oxford PhD student Alex Liu.

The Ediacarans are the earliest complex organisms before the Cambrian 'explosion of life' which marked the development of modern complex life.

But debate continues over just exactly what the Ediacarans looked like, or even what they were.

Stranger than fiction

"Some of the later species - particularly in Australia and the White Sea - do in my view seem to be early animals," says Lui. "But the morphological characteristics of earlier forms, [such as] those in Newfoundland, leave their biological affinities difficult to resolve at present - though we are working on it."

Professor Pat Vickers-Rich of Monash University in Melbourne, has recently been studying Ediacaran fossils in Namibia. She says palaeontologists originally thought the Ediacarans were jellyfish, worms and soft corals.

"Now we know they are so different to anything we know today," she says.

"Some of them were absorbers, absorbing their nutrients directly through the chemical environment with no mouth parts at all. Others, like Rangea had a kind of proboscis that grazed microbial mats."

Vickers-Rich says the Namibian fossils, from a locality called the Nama group in southern Namibia, represents the "last gasp of the Ediacaran fauna".

No one knows how the Ediacarans became extinct, but Rich hypothesises it may have been due to a build up of oxygen and changing oceanic chemistry, which may have favoured the new Cambrian animals.http://www.abc.net.au/science/articles/2010/02/17/2821290.htm

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Working out whether a snake has delivered venom with its bite may one day be determined by a simple blood test, new Australian research suggests.

The discovery could dramatically improve snakebite treatment in tropical rural areas, particularly in the developing world, where snakebite is a major health issue.

The work, previously published in Nature Scientific Reports, was presented this week at the Australian Society for Medical Research Annual Scientific Meeting in Sydney.

Senior author Dr Geoffrey Isbister, at the University of Newcastle's School of Medicine and Public Health, says the delivery of snakebite antivenom is often delayed until symptoms appear. This can sometimes be too late.

"The important thing is to be able to give the right patients antivenom early," says Isbister. "We need to identify in the first few hours if we've got envenomation."

"At the moment that is based on whether the patient feels a bit sick; but you also feel like that when you've just been confronted by a snake."

Isbister says once signs of paralysis and muscle damage begin to appear, it cannot be reversed by antivenom.

"Everyone thinks [antivenom] is this magic thing, but it doesn't reverse most things that have happened," he says.

"You've got to get the antivenom into the circulation early to bind to the snake toxins before they get to the muscles, before they get to the nerves and do the damage."

The scale of the snakebite problem is large with the World Health Organisation recognising it about four years ago as a tropical disease.

Isbister says there are one to two million cases of snake envenomation, with a potential fatality rate of 100,000 deaths worldwide.

Snakebite treatment is hampered by the availability of antivenom; high reaction rates to antivenom; and difficulties in diagnosing envenomation to allow early antivenom treatment.

Isbister says the development of a cheap diagnostic test for envenomation that can be done at the bedside is critical in addressing these issues.

Cheap detection tool

For this latest study his team, including Dr Margaret O'Leary at the University of Newcastle and Dr Kalana Maduwage from University of Peradeniya, Sri Lanka, focused on a common enzyme in snake venoms - phospholipase A2 (PLA2).

Using samples from confirmed snakebite patients in Sri Lanka and Australia they checked to see if PLA2 could be detected in the blood.

Pre-antivenom samples were collected from venomous bites from samples collected from Russell's viper, hump-nosed pit viper, Indian cobra, Indian krait and five red-bellied black snake were included in the study. These were compared with PLA2 levels in a group of un-envenomated patients.

Isbister says the levels of PLA2 were elevated in all those who had been bitten and injected with venom.

He says confirmation of envenomation means only patients who require antivenom will receive it.

"Even in a health clinic in Africa if you have antivenom then this test would help guide whether to give it rather than travelling eight hours to a hospital where it would be too late," he says.

Bringing it to the bedside

This can also have major financial implications even in developed countries such as Australia where antivenom is available at more than 90 per cent of hospitals, Isbister adds.

He says while thousands of cases of "snakebites" would appear at hospitals, only about five to 10 per cent would have envenomation.

"What comes into hospital is a suspected snakebite," he says adding this can range from being "attacked" by a stick, a bite by a non-venomous snake, to an attack from a venomous snake that didn't cause any effects.

Isbister warns against too much excitement as the analysis for this study involved expensive laboratory testing.

However, he says the "proof of concept" findings make it now feasible to begin research on development of a cheap testing kit.

"The actual test itself is not too complicated," he says, "it's working out a way you can do that simply at the bedside." http://www.abc.net.au/science/articles/2014/06/05/4018712.htm

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Jellyfish see world through complex eyes

Box jellyfish, which have no brain and only a basic nervous system, are enjoying newfound evolutionary status with research revealing they have surprisingly sophisticated eyes.

And it appears Australian jellyfish may have the most sophisticated visual systems of all.

Researchers from Lund University in Sweden studied a small Caribbean species of jellyfish, Tripedalia cystophora, found in mangrove swamps in Puerto Rico.

They report in today's issue of the journal Nature that the jellyfish boast impressive optical apparatus: a total of 24 eyes clustered at each of the creature's four corners.

While 16 eyes are simple 'pigment pits' to collect light, the remaining eight, a pair in each eye cluster, have complex lenses. 

Despite this complexity the position of the retinas means the images the jellyfish receive are blurred.

But researchers believe the sophisticated optical set-up is designed to give jellyfish a wide field of vision to help them navigate, rather than to focus on prey.

Sophisticated stingers

"This research is groundbreaking. It really drives jellyfish up the evolutionary tree," says Dr Jamie Seymour, director of the Tropical Australian Stinger Research Unit at James Cook University in Queensland.

While he says all species of box jellyfish have a visual system similar in structure, Australian box jellyfish appear to have the most sophisticated eyes of all.

Seymour says recent research conducted in the waters of Far North Queensland by Dr Dan Nilsson from the Swedish research team suggests that Australian jellyfish can see "pretty much across the entire light spectrum".

He says their vision even appears to outdo that of birds, who are at the top of the 'visual' ladder.

"Having said that, they are not capable of producing nice crisp images because the images are actually focussed behind the retina, which causes them to blur."

Needing to see

Seymour says Australian box jellyfish need superior vision "because they are active, visual hunters" compared to the Caribbean variety that live in murky waters and fed primarily on plankton.

These Caribbean species use their vision mainly to position themselves in one spot in water currents to receive their food.

http://www.abc.net.au/science/news/stories/s1366938.htm

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Fluorescent fish stoke ecological fears

When the world's first genetically-engineered fish, the glow-in-the-dark 'Night Pearl', hit the aquarium market two months ago, its Taiwan developer hoped for a sea of profits. Instead, it has suffered a barrage of criticism.

Environmentalists say that Taikong Corp's fluorescent green fish, each about 5 cm long, pose a threat to the Earth's ecosystem. European groups have been protesting against the fish - injected with a jellyfish gene - for months, and the Singapore government last week seized hundreds of the creatures at customs.

"It's difficult to make a genetic engineering breakthrough, but it's even more difficult to commercialise the product," said Fisher Lin, research manager for Taikong, a Taipei-based pet fish breeder turned biotech firm.

Environmenalists say that if the formerly colourless fresh water ricefish - which now glows green in the dark - is released into nature, it could wreak havoc on the ecosystem. But Lin insists all the transgenic fish are environmentally safe, as they are sterile.

The introduced gene comes from a natural marine organism, and the finished product - the glowing fish - is merely protein and harmless to people or other marine creatures. "The greatest worries about introducing any new GMO [genetically modified organisms] are, first of all, the impact on the ecosystem, and secondly, whether it will cause a threat to human bodies," he said.

"We still have high hopes for the transgenic fish and believe they will sell. But we also know people will have a lot of questions," he added.

Taikong has already launched a second transgenic marine creature, a fluorescent purple zebra fish that has been injected with a gene found in coral, and hopes it and the ricefish would swim into aquariums all over the world.

They also plan to introduce multicolour fluorescent pet fish, including red, purple and blue. Each transgenic fish costs US$17; about 30 times more than a colourless ricefish.

"It's very special," said 28-year-old Su Wen-ling, a graduate student who saw the fish at a biotech fair on the weekend. "But fish is innocent. I don't think it's necessary to apply genetic engineering on fish for people's viewing pleasure. There are plenty of tropical fish that are beautiful." http://www.abc.net.au/science/articles/2003/07/31/913643.htm

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Anti-venom researchers bitten hard

Australia's leading anti-venom research group may close its doors at the end of June following the withdrawal of funding from the Victorian State Government.

The Australian Venom Research Unit has developed anti-venoms to treat people bitten by the country's many poisonous animals, insects and fish for the last seven years.

More than 3,500 bite and sting victims are treated in hospitals around the country each year for potentially deadly venom-related conditions.

According to a report in The Age newspaper today, the unit's annual funding of $100,000 from the Victorian State Government, which pays for the salaries of the unit's director and deputy director, will not be renewed.

The government has told the unit's director, Dr Ken Winkel, that their funding should be the responsibility of the Federal Government.

"This is not just about Australia, it has international implications", Dr Winkel told The Age. "If this unit disappears, it will be a symbolic as well as a practical loss. People are dying every year in Australia and thousands more are dying overseas."

Last week a woman was in a critical condition after being stung by a jellyfish in Western Australia.

"This illustrates that the problems are not solved," Dr Winkel told The Age. "We still have challenges every day. There's still so much to learn about Australia's venomous creatures and managing the effects of their toxins."

A spokesman for the Victorian Department of Human Services said the unit had been given $770,000 in funding over the last seven years.

"We recognise that the unit does important work, but we're not the only beneficiary and we should not carry the financial burden," the spokesman told The Age. "We have approached the Commonwealth and they have been receptive to our approaches and to the unit's plight, but they have not made a commitment as yet."

Australia has provided international leadership in anti-venom research and is the only country to produce anti-venoms for sea snakes, box jellyfish, blue-ringed octopus and stone fish.

The venom unit provides a 24-hour advisory service to medical practitioners on the management of bites and stings, investigates the impact of envenomations on public health, and researches new anti-venoms. http://www.abc.net.au/science/articles/2001/04/30/285724.htm

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Toxic shock from stinger family

Up to eight species of small, almost invisible box jellyfish cause Irukandji Syndrome - and there is no antivenom for their potentially fatal stings.

Dr Peter Fenner, Associate Professor at the James Cook University School of Medicine, and Mr John Hadok, of the Emergency Department at Mackay Base Hospital, have documented the first reported death from Irukandji Syndrome in the in The Medical Journal of Australia.

"More than 100 people are likely to be stung and visit hospital this summer. Tragically this year, for the first time, there were two fatalities from Irukandji Syndrome in North Queensland", said Dr Fenner.

Two middle-aged men were killed by jellyfish stings earlier this year, in separate incidents near Port Douglas and in the Whitsunday Islands.

Dr Fenner believes that the jellyfish responsible for the deaths is an undescribed species of Irukandji that lives around the outer reefs and the Whitsunday Islands of the Great Barrier Reef.

The Irukandji box jellyfish, or cubozoans, are related to the deadly large box jellyfish or stinger Chironex fleckeri, which has killed more than 60 people in Australia.

Irukandji jellyfish have nematocysts, or stinging cells, on the body as well as the tentacles. When touched, these cells fire a tiny shaft into the victim's skin, that delivers the potent venom which causes Irukandji Syndrome.

The basic symptoms develop 30 minutes after being stung. They include severe low back pain; excruciating muscle cramps in arms, legs, belly and chest; sweating, nausea, anxiety, restlessness, vomiting, and headache.

The fatal cases developed such severe hypertension, or high blood pressure, that they died from brain haemorrhages, one within 30 hours after being stung.

"The Irukandji venom causes nerve endings to release large amounts of noradrenaline, the chemical that produces the "fight-or-flight" reaction", says Dr Fenner.

"The smaller blood vessels contract, which leads to the hypertension or high blood pressure, as blood is not able to squeeze through. There is no first-aid treatment for the hypertension."

"The venom is also a direct cardiac toxin, turning the heart into a floppy bag that is not able to pump blood effectively. This leads to pulmonary oedema, or fluid building up in the lungs", he says.

Irukandji Syndrome is most prevalent between early December to mid-February, along the tropical coast from Broome in WA to Rockhampton in Queensland.

Dr Fenner cautions that the development of an effective Irukandji antivenom is not presently possible, especially when the lifecycle of the species is unknown.

Dr Jamie Seymour, Senior Lecturer at the James Cook University School of Tropical Biology in Cairns, says that the syndrome was originally attributed to one species of box jellyfish named Irukandji, or Carukia barnesi.

"In the last few years, as symptoms become better defined, it appeared that people stung in Mackay were showing different symptoms from those stung in Cairns. It led us to wonder if maybe different species are involved."

"We're able to identify cubozoans by taking skin scrapings from people who have been stung, as the nematocysts stay in the skin. Each species has nematocysts of a particular shape", said Dr Seymour.

"There are nematocysts from 7 or 8 skin scrapings that I have never seen before and cannot identify. One of these samples came from the man killed at Whitsunday Islands."

Dr Seymour and other researchers are assisting Dr Fenner by netting 1800 specimens of Carukia barnesi from around Cairns for the Australian Venom Research Unit.

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