There are two known species of manta ray, the giant manta ray and the reef manta ray. Both populations are at-risk due to threats like fisheries and pollution. The IUCN lists the giant manta ray as endangered and the reef manta ray as vulnerable.
Rachel T Graham/MarAlliance
Elephants at a water pan in Hwange National Park in north western Zimbabwe. The sanctuary has a capacity for 15,000 elephants, but it currently hosts more than 45,000 according to ZimParks, the country's wildlife management authority.
Tendai Marima for NPR
Freya the walrus is pictured sitting on a boat in Frognerkilen in Oslo, Norway, on July 18. Authorities in Norway said on Sunday that they have euthanized the walrus that had drawn crowds of spectators in the Oslo Fjord after concluding it posed a risk to humans.
Tor Erik Schrøder/NTB Scanpix via AP