Science: Update

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SHRIMPS CAN see polarised light - where light waves are uniformly aligned - and can distinguish between patterns that are the same colour and brightness but differ only in the direction of polarised light they reflect. They are the first animals to be shown to have polarisation vision.

Scientists from the University of Queensland in Brisbane, the Woods Hole Institute in Massachusetts and the University of Sussex, trained shrimps to take food from boxes decorated with simple patterns of polarised sheets of plastic. The shrimps could clearly distinguish between the polarised patterns, something that is invisible to most animals, including humans. The scientists speculate in the journal Current Biology that the shrimps may use their gift to navigate, much like bees, or to communicate between each other, as they have patterns on their bodies that are more visible in polarised light.

GLOBAL WARMING is causing a damaging condition known as coral bleaching to strike the world's coral reefs more often and with greater intensity than ever before, according to a report by Greenpeace Australia. If the current rate of climate change continues, the world's coral reefs may be wiped out within 100 years. "Coral reefs could be eliminated from most areas of the world by 2100," said Professor Ove Hoegh-Guldberg, the author of the Greenpeace report.

Many coral reefs across the world were badly affected by bleaching during 1998. The term describes a condition that occurs when corals become stressed and expel the microscopic plants which give them their vibrant colour.

Professor Hoegh-Guldberg, a marine biologist with the University of Sydney, compiled the report using climate change predictions from the Australian government's scientific advisory organisation, the CSIRO, and Germany's Max Planck Institute. "Corals do not appear to show any sign that they are able to adapt fast enough to keep pace with changes in ocean temperature," he said. "The loss of these fragile ecosystems would cost billions of dollars in lost revenue from tourism and fishing industries, as well as damage to coastal regions that are protected by reefs."