Monday, April 2, 2007

Jellyfish have human-like eyes


One set of eyes on box jellyfish detect color and size of objects


A set of special eyes, similar to our own, keeps venomous box jellyfish from bumping into obstacles as they swim across the ocean floor, a new study finds.
Unlike normal jellyfish, which drift in the ocean current, box jellyfish are active swimmers that can rapidly make 180-degree turns and deftly dart between objects. Scientists suspect that box jellyfish are such agile because one set of their 24 eyes detects objects that get in their way.
“Behavior-wise, they’re very different from normal jellyfish,” said study leader Anders Garm of Lund University in Sweden.

The eyes of box jellyfish are located on cup-like structures that hang from their cube-shaped bodies.
Whereas we have one set of multi-purpose eyes that sense color, size, shape and light intensity, box jellyfish have four different types of special-purpose eyes. The most primitive set detects only light levels, but one set of eyes is more sophisticated and can detect the color and size of objects.
One of these eyes is located on the top of the cup-like structure, the other on the bottom, which provides the jellyfish with “an extreme fish-eye view, so it’s watching almost the entire underwater world,” said Garm, who will present his research at the Society of Experimental Biology’s annual meeting, in Scotland.
To test if these eyes helped the jellyfish avoid obstacles, Garm put the jellyfish in a flow chamber and inserted different objects to see if the jellyfish could avoid them. While the jellyfish could avoid objects of different colors and shapes, transparent objects proved more difficult.
“They can’t respond to the see-through ones,” Garm said.
Because jellyfish belong to one of the first groups of animals to evolve eyes (the phylum Cnidaria), Garm said, understanding how their eyes operate will show scientists what eyes were like early in evolutionary time.

Sunday, April 1, 2007

Tsunami hits Solomons; 8 reported dead

HONIARA, Solomon Islands - A powerful undersea earthquake Monday in the South Pacific sent a tsunami several yards high crashing into the Solomon Islands, devastating at least one village, officials and residents said.
Police and residents said a wave about 10 feet high struck the western town of Gizo, inundating buildings and causing widespread destruction. A man who answered the telephone at the Gizo police station said there were initial reports that eight people, six of them children, had been killed by the tsunami but they were still unconfirmed. The phone cut out abruptly before the man gave his name.
Gizo resident Judith Kennedy said water "right up to your head" swept through the town.
"All the houses near the sea were flattened," she told The Associated Press by telephone. "The downtown area is a very big mess from the tsunami and the earthquake," she added. "A lot of houses have collapsed. The whole town is still shaking" from aftershocks.
The
U.S. Geological Survey' said the quake measured magnitude-8.0 and struck at 7:39 a.m. about 6 miles beneath the sea floor, 217 miles northwest of the capital, Honiara.
The Pacific region from Australia to Hawaii went on high alert for several hours after the quake struck between the islands of Bougainville and New Georgia, though officials canceled a region-wide tsunami warning after the danger period passed.
Gizo, a regional center, is just 25 miles from the earthquake's epicenter.
Another witness in the town, dive shop owner Danny Kennedy, estimated the height of the wave at 10 feet.
"I'm driving down the street — there are boats in the middle of the road, buildings have completely collapsed and fallen down," he said in a telephone interview.
"We're just trying to mobilize water and food, and shelter for people at the moment because ... in the town alone there's going to be between 2,000-3,000 homeless. It's not a very good scene at the moment."
Harry Wickham, who owns a waterfront hotel in Gizo, said the damage was widespread.
"The waves came up probably about 10 feet and swept through town," he told Australia's Nine Network television by telephone. "There's a lot of water damage and a lot of debris floating around," he added.
"Ten feet of water washing through town — you can imagine what damage it has done here."
Julian McLeod of the Solomon Islands National Disaster Management Office said there were unconfirmed reports that two villages in the country's far west were flooded.
"Two villages were reported to have been completely inundated," McLeod told Australian Broadcasting Corp. radio. "We have received reports of four people missing."
A town in the west, Munda, was believed to be badly damaged, officials and the Solomon Islands Broadcasting Corp. said, but communications were difficult and details were not confirmed.
The Hawaii-based Pacific
Tsunami' Warning Center reported the quake at magnitude 8.1, and said a temblor of that strength could cause a destructive tsunami and issued a warning bulletin for the Solomon Islands and neighboring Papua New Guinea.
It ordered a lower-level "tsunami watch" for other places, including most South Pacific countries, but later canceled the alert. The center said a 6-inch wave had been reported in Honiara.
Police Sgt. Godfrey Abiah said in Honiara that police in Gizo had received warning about a possible tsunami and were helping people leave the town for higher ground when the wave hit.
"We have lost radio contact with the two police stations down there and we're not getting any clear picture from down there," he told The Associated Press by telephone.
A spokesman for Prime Minister Manasseh Sogavare, Deli Oso, said the quake was felt in Honiara but there were no reports of any damage.