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)

In this September 30, 2017 photo, people perform “transvestite target practice” to protest the killings of transvestite prostitutes during the annual LGBQT march in Asuncion, Paraguay. Advocacy groups fear the stigma and attacks against the LGBQT community could get worse now that the country's education minister has banned classes about sexual diversity in schools and even volunteered to help burn all books related to the subject. (Photo by Jorge Saenz/AP Photo)

A rescued malnourished sea lion is manually fed a fish at Sea World in San Diego, California March 17, 2015. Animal rescue centers in California are being inundated with stranded, starving sea lion pups, raising the possibility that the facilities could soon be overwhelmed, the federal agency coordinating the rescue said. (Photo by Mario Anzuoni/Reuters)

Participants in the 18th Annual “No Pants Subway Ride” travel in the subway on January 13, 2019 in New York. The “No Pants Subway Ride” is an annual event started in 2002 by Improv Everywhere in New York, the goal of which is for riders on the subway train to dress in normal winter clothes without pants while keeping a straight face. (Photo by Johannes Eisele/AFP Photo)

Passengers wear no trousers as they ride the London Underground in London, Britain, 07 January 2018. The No Pants Subway Ride is an global annual event where people take the public transport while they are not wearing trousers to surprise other passengers. This event takes place on the first Sunday of every year in the world's major cities. (Photo by Tolga Akmen/EPA/EFE/Rex Features/Shutterstock)

Young people wearing no pants participate in the “No Pants Subway Ride” in New York City, 13 January 2019. No Pants Subway Ride is an annual global event started in New York, USA in 2002. (Photo by William Volcov/ZUMA Press)

A destroyed T-72 tank, which presumably came from Russia, is seen on a battlefield near separatist-controlled Starobesheve, eastern Ukraine, October 2, 2014. The burnt-out remains of dozens of tanks and armoured vehicles in fields near the small village of Horbatenko bear witness to the ferocity of a battle that turned the tide of the conflict in eastern Ukraine. Among the debris, Reuters found the blackened carcasses of what military experts have since identified as two Russian army tanks, supporting statements by Kiev and the West that the rebels were backed by troops and equipment sent by Moscow. (Photo by Maria Tsvetkova/Reuters)

Yan Zhengming (R), 94, and his wife Zhou Suqing (C), 90, attend their wedding ceremony at their home, on the 70th anniversary of their marriage, in Quxian county of Dazhou, Sichuan province, China, May 15, 2015. The wedding, organized by local charity groups, was a long-time wish of veteran of the World War Two Yan, who married Zhou 70 years ago, but could not afford to have a wedding ceremony, local media reported. (Photo by Reuters/Stringer)