An Amur tiger walks across a passageway after a news conference at the Philadelphia Zoo, Wednesday, May 7, 2014, in Philadelphia. The see-through mesh pathway called Big Cat Crossing is part of a national trend called animal rotation that zoos use to enrich the experience of both creatures and guests. (Photo by Matt Slocum/AP Photo)

Lebanese students dance during “The Big Dance” event in downtown Beirut, near the parliament May 9, 2015. About 1000 students from all over Lebanon gather and take part in a joint dance with the aim of encouraging people to get into dance and increase fitness levels. This initiative is part of the British Council's project, Connecting Classrooms which aims at building links between schools in the UK and Lebanon. (Photo by Aziz Taher/Reuters)

A fire engine drives away from flames on the ridge, east of Silverwood Lake in Crestline, Calif., Sunday, August 7, 2016. (Photo by Terry Peirson/The Press-Enterprise via AP Photo)

These romantic sepia shots show lovers enjoying quiet, unguarded moments together – but the subjects are not besotted couples; they are fearsome big cats. Freelance snapper Goran Anastasovski has devoted more than 10 years of his life to photographing big cats and other animals. The 46-year-old from Macedonia aims to emphasize their human qualities in his photographs. (Photo by Goran Anastasovski/Caters News)

A surfer drops in on a large wave at Praia do Norte, in Nazare December 11, 2014. Praia do Norte beach has gained popularity with big wave surfers since Hawaiian surfer Garrett McNamara broke a world record for the largest wave surfed here in 2011. (Photo by Rafael Marchante/Reuters)

A Belgian shrimp fisherman rides a carthorse to haul a net out in the sea to catch shrimps during low tide at the coastal town of Oostduinkerke, Belgium July 3, 2015. At the end of each fishing session, the fishermen and their mounts leave the water to empty the net's contents into two wicker baskets fixed on each side of the horse. This traditional method of catching shrimps along the North Sea coast, which dates back to some 500 years, attracts tourists every summer. In 2013, Unesco recognized shrimp fishing on horseback as an intangible cultural heritage. (Photo by Yves Herman/Reuters)

Fishermen prepare fish from their vessels on the shores of the Gulf of Aden in the city of Bosasso, northern Somalia's breakaway Puntland region December 17, 2016. (Photo by Feisal Omar/Reuters)

The photographs feature fish that have been specially treated to make the stained skeletal tissues visible through the skin and flesh. The technique, developed by Dr. Adam Summers, uses dyes, hydrogen peroxide, a digestive enzyme and glycerin to make the flesh seem to disappear. Photo: This image of the butterfly ray (Gymnura crebripunctata) helped scientists study the joints in its wings. (Photo by Adam Summers)