Workers at a Tokyo aquarium are scratching their heads after the deaths of dozens of fish that have left just one lonely tuna roaming a once-flourishing tank.

The park on Tuesday found the second last fish floating dead in its vast doughnut-shaped enclosure that was once home to nearly 160 fish and among the venue's most popular attractions, said a spokesman for Tokyo Sea Life Park.

India's famously frugal Mars mission has been extended by around six months thanks to a surplus of fuel on board the spacecraft, the country's space agency said Tuesday.

The Mars Orbiter Mission spacecraft had been scheduled to wrap up its mission this month after India in September became the first Asian nation to reach the Red Planet, all on a shoe-string budget.

Scientists in Portugal have uncovered the fossils of a previously unknown crocodile-like creature that was among the Earth's top predators more than 200 million years ago.

The remains found on the site of an ancient lake suggest the creature was like a giant salamander, according to a study released Monday.

Human feces contains gold and other precious metals that could be worth hundreds of millions of dollars, experts say.

Now the trick is how to retrieve them -- a potential windfall that could also help save the planet. 

African elephants could be extinct in the wild within a few decades, experts warned on Monday at a major conservation summit in Botswana that highlighted an alarming decline in numbers due to poaching.

The Africa Elephant Summit, held at a tourist resort in Kasane, gathered delegates from about 20 countries across Europe, Africa and Asia, including China -- which is accused of fuelling the illegal poaching trade.

Four years after a towering tsunami ravaged much of Japan's northeastern coast, efforts to fend off future disasters are focusing on a nearly 400-kilometer (250-mile) chain of cement sea walls, at places nearly five stories high.

Opponents of the 820 billion yen ($6.8 billion) plan argue that the massive concrete barriers will damage marine ecology and scenery, hinder vital fisheries and actually do little to protect residents who are mostly supposed to relocate to higher ground. Those in favor say the sea walls are a necessary evil, and one that will provide some jobs, at least for a time.

A tiny central Pacific community, forced to evacuate their homes because of U.S. nuclear testing, are now demanding refuge in the United States as they face a new threat from climate change.

"We want to relocate to the United States," Nishma Jamore, mayor of the atoll of Bikini, said on the weekend as Pacific waters continued to eat away at the small Kili and Ejit islands in the far-flung Marshall Islands archipelago.

Nine whales died Monday after stranding themselves against a rocky breakwater on Australia's east coast, with experts working to herd the rest of their group out to sea.

About 20 long-finned pilot whales got into trouble in Bunbury harbour, 175 kilometers (110 miles) south of Perth, Western Australia's Department of Parks and Wildlife said.

A Chinese airline on Saturday completed the country's first commercial flight using biofuel, made from waste cooking oil, as the government seeks to promote greater environmental sustainability.

A Hainan Airlines flight from commercial hub Shanghai to Beijing used biofuel supplied by China National Aviation Fuel company and energy giant Sinopec, according to a statement from U.S. aircraft giant Boeing.

The widely-held vision of Neanderthals as brutes may need a stark rethink after research found they crafted the world's earliest jewellery from eagle talons 130,000 years ago, long before modern humans appeared in Europe.

"While reviewing eight, white-tailed eagle talons and an associated phalanx, on the latter I noticed numerous cut marks and a revelation just struck me -- they were made by a human hand," Davorka Radovcic, a curator at Croatia's Natural History Museum, told Agence France Presse.