Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

Respect, Kronotsky nature reserve, Russia. The photographer’s cat, Ryska – her name means little lynx in Russian – stands outside their cabin and with aggressive posturing warns off a fox. In winter, foxes would regularly visit the cabin searching for food. If one peered in at the window, possible when the snow was deep, Ryska would sit on the other side, fur raised, and growl. When outside, she would hold her ground. The foxes were not always frightened and so encounters could be a sort of dance. (Photo by Igor Shpilenok/Unforgettable Behaviour/NHM)

“The giant clam, Tridacna gigas (known as pā’ua in Cook Islands Māori), is the largest living bivalve mollusc. T. gigas is one of the most endangered clam species. It was mentioned as early as 1825 in scientific reports. One of a number of large clam species native to the shallow coral reefs of the South Pacific and Indian oceans, they can weigh more than 200 kilograms (440 lb) measure as much as 120 cm (47 in) across, and have an average lifespan in the wild of 100 years or more”. – Wikipedia

Photo: Tridacna Gigas, or Giant Clams spew water as a traditional fisherman passes by a small sanctuary on January 23, 2004 near Bolinao in the Northern Philippines. The clams, prime builders for coral reefs and providing shelter for spawning fish and other marine life, are exposed by low tides in the sanctuary. Overfishing and pollution throughout the country are not only threatening food security, but are also starting to choke one of the few working clam sanctuaries in the world. (Photo by David Greedy/Getty Images)

A couple enjoys the view of the ethnographic and amusement center Kremlin in Izmailovo reflected in the Serebryano-Vinogradnii lake in Moscow, Russia on July 30, 2017. (Photo by Mladen Antonov/AFP Photo)

This aerial photo taken on March 2, 2023 shows bulldozers working to build high-standard farmlands in Pucheng County, southeast China's Fujian Province. A new round of high-standard farmlands building is underway in Pucheng County in preparation of spring ploughing. (Photo by Xinhua News Agency/Rex Features/Shutterstock)

Instructor Raquel Potí leads a stilt walking workshop at the Museum of Modern Art in Rio de Janeiro, Brazil, Saturday, January 27, 2024. Potí is chiefly responsible for the explosion of stilt walking in Rio, having trained more than 1,000 kids and adults over the past decade. (Photo by Silvia Izquierdo/AP Photo)

Keen diver Yusuke Fukami fulfilled a personal dream by snapping a cartoon-like Costasiella sea slug while in Bali in the last decade of December 2024. (Photo by Yusuke Fukami/South West News Service)