The week in wildlife

Nagykoerue, Hungary: Mayflies swarm on the Tisza river. Every year from late spring to early summer, millions of long-tailed mayflies rise in huge clouds, take flight, reproduce, and perish, all in just a few hours Photograph: Janos Meszaros/EPA

The foot of a Trichobatrachus robustus, aka a hairy frog, which is one of the 11 species of African frogs that carry a built-in concealed weapon - they can sprout claws on demand to fight off attackers Photograph: Harvard University/Reuters

Santa Clara de San Carlos, Costa Rica: Crocodile offspring, part of 190 hatched in captivity two weeks ago, remain in a pond at the crocodile farm inside the San Carlos technological institute Photograph: Yuri Cortez/AFP

A breadcrumb sponge. About a third of all types of fish and other marine life have been wrongly named by scientists, complicating efforts to conserve what could be a million marine species Photograph: Bernard Picton/Reuters

Amsterdam, Netherlands: A gorilla holds her newborn baby at Artis zoo. The baby was fathered by a guest gorilla, borrowed from a German safari park after the Dutch zoo found it could not breed using its own males Photograph: Evert Elzinga/AFP

Jeju Island, South Korea: Agave plants appear in a garden. They are said to bloom only once every 100 years Photograph: EPA

Singapore: Giraffes look into the camera as they wait to be fed by visitors at the zoo, which recently opened its feeding sessions to the public as part of efforts to educate people about wildlife and depleting natural resources Photograph: Wong Maye-E/AP

Moorhead, US: A handful of catfish fry in their hatchery. Rising costs of feed, fuel and transportation costs are forcing some longtime commercial catfish farmers from the business in the economy starved Delta Photograph: Rogelio V Solis/AP

Chisinau, Moldova: A parrot performs a stunt. The upper mandible of a parrot is not fused to the skull, which allows it to move independently, contributing to the tremendous biting pressure these birds are able to exert. Photograph: Dunitru Doru/EPA

Valle del Cauca, Colombia: A girl holds an owl butterfly. Colombia is the country with the greatest diversity of diurnal butterflies in the world, with approximately 3,500 species Photograph: Carlos Julio Martinez/AFP

St Paul Island, Alaska: A male fur seal defends its territory on a beach. Thousands of pounds of marine debris, including commercial fishing nets, crab pots, and ropes, wash up from the world's biggest fisheries endangering the fur seal and other marine life that come to the island to breed Photograph: Al Grillo/AP

Takeo province, Cambodia: A male hairy-nosed otter (Lutra sumatrana) eats fish at Phnom Tamau zoo. In Cambodia, hairy-nosed otters are being hunted for skins which are sold on by middlemen to China in large numbers Photograph: Conservation International/AP

Menorca: Two goats during a sunset. Goats are reputed to be willing to eat almost anything. Their digestive system allows almost any organic substance to be broken down and used as nutrients Photograph: Dani Cardona/Reuters

Anchorage, Alaska: Korol, a four-year-old, 450lb Amur tiger, walks around his new home. The zoo has welcomed two new rare Siberian tigers, the largest of the big cats. There are believed to be about 400 of the critically endangered cats in the wild Photograph: Marc Lester/Anchorage Daily News/AP

Sofia, Bulgaria: A Himalayan black bear cools off on a hot day in the city zoo. The Himalayan black bear is greatly in need of conservation due to a high infant mortality rate and extensive hunting. This species occurs throughout Myanmar and is most populous in the mountainous country and jungle Photograph: Valentina Petrova/AP