In this November 28, 1966 file photo, one of the 10 beagles involved in the first test of the Veterans Administration Hospital in East Orange, N.J. smokes a cigarette through a machine linked to its windpipe by a plastic tube to test any link between smoking and emphysema. (Photo by AP Photo)

After 12 years photographing models, musicians, and celebrities, Brad Wilson decided that he wanted to photograph something a little more unpredictable: wild animals. Photo: Serval. (Photo by Brad Wilson)

A handout photograph provided by Brian Kubicki of Costa Rican Amphibian Research Center on 26 April 2016 shows a “Crystal frog”, Hyalinobatrachium dianae (H. diane). This frog was discovered by US biologist Brian Kubicki and Costa Ricans Stanley Salazar and Robert Puschendorf in a rainy forest of Costa Rican caribbean after 40 years without notice of any new example of this kind. (Photo by Brian Kubicki/EPA/Costa Rican Amphibian Research Center)

Two men standing on a high catwalk, surveying the construction of the Brooklyn Bridge, with Manhattan in the background, New York City, 1877. (Photo by Museum of the City of New York/Archive Photos/Getty Images)

Armed with only paper, graphite and coloured pencils – plus his vivid imagination – the artist creates remarkable drawings that leap from the page when photographed. The 32-year-old, from Alkmaar in Holland, began experimenting with anamorphic 3D drawing five years ago. Photo: Ramon Bruin’s 3D illustration of two twins drawing each other. (Photo by Ramon Bruin/Medavia)

Model Lily Donaldson flashes the peace sign as she leaves Victoria's Secret Fashion Show China casting in New York City on August 22, 2017. (Photo by Christopher Peterson/Splash News and Pictures)

These hilarious images show dogs enjoying a day out exploring New York’s most iconic tourist hotspots Photographer Mark McQueen captured the canines hanging out near landmarks like the Brooklyn Bridge, on 5th Avenue and Times Square. Here: Take my picture! Apartment dogs in the East Village are always happy to be out for a walk. (Photo by Mark McQueen/Caters News Agency)

These “snapcats” have found their bunny doppelgängers in a series of sweet photo shoots. Animal photographer Mark Taylor, from Surrey, England, and his assistants have scoured the U.K. to bring together carbon-copy rabbits and cats. Here: Chocolate Birman-cross kitten with chocolate Lop rabbit. (Photo by Mark Taylor/Warren Photographic/Caters News Agency)