A polar bear in a German zoo died and its companion barely survived after they fell sick with a mutated encephalitis virus that originated in zebras, scientists say.

The finding is a concern, for it shows how rare species in zoos can be at risk from species-jumping pathogens, they say.

Belgium stepped up controls on nuclear safety that found cracks in the casing of an ageing reactor and led to two sites now closing after learning of signs of fissures in French atomic power plants, the national watchdog said Thursday.

Controls carried out in 2004 on a site in southern France revealed "indications of fissures" in base material "perpendicular to the (reactor's) surface" which were "dangerous", the head of Belgium's federal agency for nuclear safety AFCN Willy de Roovere told media.

Australian scientists said Friday there was now "striking evidence" of extensive southward migration of tropical fish and declines in other species due to climate change, in a major ocean report card.

Compiled by more than 80 of Australia's leading marine experts for the government science body CSIRO, the snapshot of global warming's effects on the island continent's oceans warned of "significant impacts".

Scientists have found a cosmic supermom. It's a galaxy that gives births to more stars in a day than ours does in a year.

Astronomers used NASA's Chandra (SHAWN'-drah) X-Ray telescope to spot this distant galaxy creating about 740 new stars a year. By comparison, our Milky Way galaxy spawns about one new star each year.

Seychelles and Germany have the healthiest seas of any inhabited territory, while Sierra Leone has the unhealthiest, according to a new index that says many oceans score poorly for biodiversity and as a human resource.

Topping the list with a score of 86 out of 100 was the uninhabited South Pacific territory of Jarvis Island, owned by the United States, as well as a clutch of other unpopulated Pacific Ocean islands.

A flight test of an experimental unmanned vehicle designed to fly at hypersonic speeds has ended in failure, the U.S. Air Force said Wednesday.

The X-51A Waverider was dropped from a B-52 bomber Tuesday and launched by a rocket booster as planned but the flight was over in seconds after a control fin malfunctioned, the Air Force said in a statement.

Lion bones have become a hot commodity for their use in Asian traditional medicine, driving up exports from South Africa to the East and creating new fears of the survival of the species.

Conservationists are already angry over lion trophy hunting.

The United States Air Force planned a key test Tuesday of an experimental aircraft designed to fly at six times the speed of sound, which is about 3,600 mph (6,000 kph).

The unmanned X-51 WaveRider was expected to reach Mach 6 after being dropped by a B-52 bomber and taking flight off the Southern California coast near Point Mugu. Engineers hoped the X-51 would sustain its top speed for five minutes, twice as long as it's gone before, NBC reported.

The Bicknell's thrush, a rare songbird that breeds atop mountains in the northeastern United States and winters in the Caribbean, is being considered for endangered species status, the U.S. Fish and Wildlife Service announced Tuesday.

The sparrow-sized brown bird, which nests at elevations over 3,000 feet (914 meters) in New York, Maine, New Hampshire and Vermont, has one of the most limited breeding and wintering ranges of any bird in North America. The main threat to the bird is climate change that's reducing its boreal mountain habitat of spruce and fir forest, said Mollie Matteson of the Center for Biological Diversity in Richmond, Vermont.

NASA's newest rover Curiosity has yet to make its first move on Mars, but scientists said Tuesday they are already mapping out possible driving routes to a Martian mountain.

Since landing in Gale Crater near the equator last week, the nuclear-powered rover has been busy getting a head-to-wheel health checkup while parked. It touched down about 5 miles (8 kilometers) from Mount Sharp where signatures of past water have been spotted at the base.