Numbat populations once dropped as low as 500 adults. To help save this endangered marsupial, the Perth Zoo has been rearing them in captivity for release back into the wild. But wild numbats eat only termites, which are too difficult to get in large quantities. So zoo staff have spent over a decade concocting a tasty and nutritious substitute. Helenabella via Wikimedia Commons hide caption

itoggle caption Helenabella via Wikimedia Commons

Sir David Attenborough at the Beijing Museum of Natural History with fossil of Juramaia, as featured in the Smithsonian Channel series Rise of Animals: Triumph of the Vertebrates. Courtesy Smithsonian Channel hide caption

itoggle caption Courtesy Smithsonian Channel

Cholita, an Andean bear, was abused in a circus in Peru and is now in a small zoo. An animal welfare group has now received permission to take Cholita to a wildlife sanctuary in Colorado, along with more than 30 former circus lions. Courtesy of Animal Defenders International hide caption

itoggle caption Courtesy of Animal Defenders International

This black bear was spotted atop a tree in Tampa, Fla., on May 17, 2013. The bear population has been on the rise, so state wildlife officials are calling for a bear hunting season. Skip O'Rourke /MCT /Landov hide caption

itoggle caption Skip O'Rourke /MCT /Landov

The European eagle owl, like this one from the Mulhouse Zoo in eastern France, is one of the largest owl species, with a wingspan of about 6 feet. Sebastien Bozon/AFP/Getty Images hide caption

itoggle caption Sebastien Bozon/AFP/Getty Images

Laurie McCannon, director of the Northeast Animal Shelter in Salem, Mass., with a dog named Trina. Three-quarters of the dogs adopted from the shelter in 2013 were from out of state. Shannon Mullen for NPR hide caption

itoggle caption Shannon Mullen for NPR

A puppy waits at an adoption event in Miami last year. The city is now considering a ban on the sale of puppies in retail pet stores. Cities and towns in several states have passed similar bans, aimed at cracking down on substandard, large-scale puppy breeders. Wilfredo Lee/AP hide caption

itoggle caption Wilfredo Lee/AP

A curious cuttlefish stares back at the camera from inside The Smithsonian's National Zoo Invertebrate Exhibit. The exhibit, home to dozens of small aquatic and terrestrial species without backbones, closed on Sunday. Meghan Murphy/Smithsonian's National Zoo hide caption

itoggle caption Meghan Murphy/Smithsonian's National Zoo