The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)

A pine marten – one of a few wild mammals doing well in Britain (although they number just 3,700). A fifth of the country’s wild mammals are at high risk of extinction, research shows. (Photo by Maurice Flynn/The Mammal Society)

A Bengal tigress who gave birth to four cubs at the Guadalajara Zoo, Jalisco state, Mexico runs at the zoo on October 5, 2021. (Photo by Ulises Ruiz/AFP Photo)

A young male fiddler crab is dwarfed by an older male of the same species, looming behind it at Morua estuary, in the Gulf of California, Mexico on January 4, 2022. Whereas female fiddler crabs have small claws of equal sizes, the males’ pincers can vary in size, with the small one used to pick up food and the larger to impress females. (Photo by Claudio Contreras/Solent News)

A red squirrel leaps over a gray squirrel after the larger squirrel became annoyed with its territory being encroached upon, Saturday, May 28, 2022, in Freeport, Maine. (Photo by Robert F. Bukaty/AP Photo)

Cheetah Darcy enjoys her newly-developed Cheetah Territory that covers 10,000 square at Yorkshire Wildlife Park, near Doncaster, UK on Wednesday, August 16, 2023. Darcy, who is four-years-old, travelled from Ireland's Fota Wildlife Park to YWP last week where she will be joined by 13-year-old male Brooke who is on his way from the Bristol Zoo Project as a recommendation by the European Endangered Species Programme. (Photo by Danny Lawson/PA Images via Getty Images)

This photo taken on September 1, 2023 shows a one-day-old female Sumatran elephant by her 41-year-old mother elephant named Lisa at the Elephant Flying Squad camp in the Tesso Nilo National Park in Pelalawan, Sumatra. (Photo by Wahyudi/AFP Photo)

The photographer Yan Hidayat says his pet Pacman frog and Brazilian turtle are inseparable. He still had to wait four hours to get this photo in West Sumatra, Indonesia, in the first decade of March 2024. (Photo by Yan Hidayat/Media Drum Images)