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

A brown bear in its natural habitat. Wildlife ecologists in Minnesota found that black bears in their study experienced an increase in heart rate when buzzed by drones. iStockphoto hide caption

itoggle caption iStockphoto

A juvenile California two-spot octopus (Octopus bimaculoides). Michael LaBarbera/Nature hide caption

itoggle caption Michael LaBarbera/Nature

Can you guess which eyes belong to what animal? Top row, from left: cuttlefish, lion, goat. Bottom row, from left: domestic cat, horse, gecko. Top row: iStockphoto; bottom row: Flickr hide caption

itoggle caption Top row: iStockphoto; bottom row: Flickr

Ready, set, fly! The ball bearings glued to this bumblebee's legs simulate the weight and placement of pollen loads. The tag on the insect's back is a lightweight sensor, designed to track its movements in flight. Courtesy of Andrew Mountcastle hide caption

itoggle caption Courtesy of Andrew Mountcastle

Life reconstruction of Wendiceratops pinhorn. Danielle Dufault/PLOS ONE hide caption

itoggle caption Danielle Dufault/PLOS ONE

Mammoths had a distinctive version of a gene known to play a role in sensing outside temperature, moderating the biology of fat and regulating hair growth. That bit of DNA likely helped mammoths thrive in cold weather, scientists say. Courtesy of Giant Screen Films, 2012 D3D Ice Age, LLC/Penn State University hide caption

itoggle caption Courtesy of Giant Screen Films, 2012 D3D Ice Age, LLC/Penn State University

One of the 20 GPS sensors deployed on Greenland's Helheim Glacier to track its movement. Alistair Everett/Swansea University hide caption

itoggle caption Alistair Everett/Swansea University

An illustration of Pappochelys, based on its 240-million-year-old fossilized remains. This ancestor to today's turtle was about 8 inches long. Rainer Schoch/Nature hide caption

itoggle caption Rainer Schoch/Nature

The long "oral arms" of the adult moon jelly, Aurelia aurita, extend from near its mouth, in the center of the bell. Magnus Manske/Wikimedia Commons hide caption

itoggle caption Magnus Manske/Wikimedia Commons