Two octopuses going at it — or, as marine biologist Peter Godfrey-Smith might put it, engaging in a bit of "ornery behavior. Peter Godfrey-Smith (CUNY and University of Sydney), David Scheel (Alaska Pacific University), Stefan Linquist (University of Guelph) and Matthew Lawrence. hide caption

itoggle caption Peter Godfrey-Smith (CUNY and University of Sydney), David Scheel (Alaska Pacific University), Stefan Linquist (University of Guelph) and Matthew Lawrence.

California condors have enormous wingspans. That's fine in the wilderness, but when a bird of this size encounters a power line, the results can be fatal. The San Diego Zoo Safari Park has a program to help train birds to avoid the hazard. Jon Myatt/U.S. Fish and Wildlife Service/Flickr hide caption

itoggle caption Jon Myatt/U.S. Fish and Wildlife Service/Flickr

Professor Douglas Causey logs information as he tags and takes basic measurements of the birds he harvested in the Aleutian Islands on June 4. He is looking at the birds' blood and their diet, hoping to find out the ways the ocean is changing as it warms. Bob Hallinen/ADN hide caption

itoggle caption Bob Hallinen/ADN

Cattle rancher Craig Vejraska pours out feed while checking on his cattle in a smokey field in Cox Meadow, as the Okanogan Complex fires burn outside Omak, Wash., Aug. 26, 2015. Ian C. Bates/for NPR hide caption

itoggle caption Ian C. Bates/for NPR

Male and female tungara frogs. Among these frogs, the guy with the best call usually wins the gal — except when you throw a third-choice loser into the mix. Alexander T. Baugh/Encyclopedia of Life hide caption

itoggle caption Alexander T. Baugh/Encyclopedia of Life

Male treehoppers make their abdomens thrum like tuning forks to transmit very particular vibrating signals that travel down their legs and along leaf stems to other bugs — male and female. Courtesy of Robert Oelman hide caption

itoggle caption Courtesy of Robert Oelman

By law, all wild swans in Great Britain belong to Queen Elizabeth. Alpha/Landov hide caption

itoggle caption Alpha/Landov

Giant panda Mei Xiang, together with her cub Bao Bao at the National Zoo in 2014. As of Saturday, Bao Bao now has another sibling: Her mother just gave birth to a cub. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images