November 21, 2009

Light Shed on Mysteries of Deadly Jellyfish


Box jellyfish are odd creatures. Some species have 24 eyes. They mate in mass spawning, during which males and females never touch while they release sperm and eggs into the ocean and let nature take its course.

Most interest to humans is the fact that box jellyfish can be deadly. But because jellyfish don't make for good fossils, and few jellies exist in museum collections, little is known about their evolutionary history or the relationships between different species.

Now scientists have gained new information about the distribution, relationships and evolution of these deadly sea creatures, findings that could eventually help researchers generate antivenom to save lives.

Who's related to whom

Box jellies, also called sea wasps, stingers or fire jellies, live primarily in warm coastal waters around the world. They are particularly well known in Australia, the Philippines and the rest of southeast Asia, but they also occur in Hawaii and in waters off the United States Gulf and East Coasts. Some are harmless, others cause death to humans in just minutes.

Named for their box or cube-shaped body, these animals are members of Cubozoa, the smallest class of Cnidaria, animals ranging from sea anemones and corals to Portuguese man of war and true jellyfish, all of which possess stinging capsules known as nematocysts.

Using DNA extracted from tissue samples, the researchers used a number of genetic tests and analytical techniques to trace the evolution of the various species and their toxicity and to sort out misidentified species. Among the findings: Box jellies may contain a unique family of proteins that, with further study, could help create antivenoms.

The Australian box jellyfish (Chironex fleckeri), the largest box jellyfish species, is considered the most venomous marine animal and its sting can be fatal. Its close relative, Chironex yamaguchii, has caused deaths in Japan and the Philippines. A much smaller species, Carukia barnesi, is the first species known to cause Irukandji Syndrome. Symptoms include severe low back pain, nausea, headache and vomiting, and sometimes “an impending feeling of doom”, but the syndrome is usually not life-threatening. Other box jellyfish species are now known to cause the same symptoms.

“Knowing who is related to whom among the box jellyfish will be very helpful in making predictions about species that are not well known,” said NOAA researcher Allen Collins. Its possible an antivenom that works for one species might work for another, he said.

Where they are

Other species of jellyfish are known to swarm and takeover parts of the oceans. Box jellies don't seem to move around as much as some species, however. The study revealed several patterns in the global distribution of box jellyfish species. Some live exclusively in the Atlantic, others in the Pacific, and still others are found in the Indian Ocean.

"Geography seems to isolate species and most don’t seem to cross open ocean habitats," the researchers said in a statement. "A few are found in all three oceans and may live in tropical regions around the globe."

The study, funded by the National Science Foundation and the PADI Foundation, is detailed in the Proceedings of the Royal Society.



Editor: jimbon

Source : LiveScience

http://m.kompas.com

November 19, 2009

These Stones Really are Rolling



The rocks, some as heavy as 17 stone, edge along in bizarre, straight-line patterns across the ultra-flat surface of the valley. They can travel more than 350 yards a year.

Scientists believe the phenomenon is caused by a coming together of specific weather conditions. Studies suggest a combination of 90mph winds, ice formations at night and thin layers of wet clay on the surface of the desert all help to push them along.

These extraordinary pictures reveal a bizarre event that is puzzling the science world - rocks that glide across the desert. Amid the eerie silence and the 50C heat of California's Death Valley these giant boulders appear to move smoothly - and unaided - across the desert.

Photographer Mike Byrne, 40, has spent years documenting the stones' mysterious movements. As his amazing pictures show these real-life rolling stones leave trails across the sand in places almost untouched by man.

He said: 'Some of these rocks are as heavy as a person, it is really is strange to imagine them gliding across the desert like this.

'They must be the original real-life rolling stones, they just keep moving through the sand and I don't believe anyone has really 100 per cent worked it out yet.

'Most of the stones are found on an old lake bed, known as the Racetrack Playa, where the ground is particularly flat.

'It has been documented over the years and it is something very special to witness, although I know climatologists believe the phenomenon could disappear in a few years as the temps continue to rise.

'One of the strongest theories about what the rocks move is that water rising from beneath the surface of the sand is pushed by the wind creating a surface the rocks can move along.'

Death Valley is the lowest point in the U.S., at 282ft below sea level. It is almost completely flat and holds the record for the second highest temperature ever recorded on earth, a blistering 58C.

In the 1990s a study by a team of scientists lead by Professor John Reid, from Hampshire College, Massachusetts, attempted to explain the rocks' movement. His study concluded that the rocks may be moved when they become embedded in sheets of ice forming at night on the surface of the sand.

As the sand melts Prof Reid said that the rocks were moved along by the ice and wind, thus forming the patterns.



Editor: jimbon
Source : The Daily Mail
kompas.com