As seals dive more frequently—and for longer—than humans do, the range of carbon dioxide in their bodies varies more widely.

A group of tufted ducks play in the water at the Xiamen Horticulture Expo Garden in Xiamen, Fujian province. [Photo by Chen Bo/For chinadaily.com.cn] A group of black and white tufted ducks ...

Etienne Francey (Switzerland) uses his camera to create an impressionist view of tufted ducks. Looking out over Switzerland’s Lake Neuchâtel, Etienne homed in on the tufted ducks, which had formed a ...

A group of tufted ducks play in the water at the Xiamen Horticulture Expo Garden in Xiamen, Fujian province. [Photo by Chen Bo/For chinadaily.com.cn] ...