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)

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)

Villagers from the Porto Novo community load into their canoes arapaima or pirarucu, the largest freshwater fish species in South America and one of the largest in the world, while fishing in Poco Fundo lake along a branch of the Solimoes river, one of the main tributaries of the Amazon, in the Mamiraua nature reserve near Fonte Boa about 600 km (373 miles) west of Manaus, November 26, 2013. Catching the arapaima, a fish that is sought after for its meat and is considered by biologists to be a living fossil, is only allowed once a year by Brazil's environmental protection agency. The minimum size allowed for a fisherman to keep an arapaima is 1.5 meters (4.9 feet). (Photo by Bruno Kelly/Reuters)

The fin of a tuna is seen on display in the outer part of the Tsukiji fish market, the Jogai Shijo, in Tokyo January 4, 2015. The famous Tsukiji wholesale fish and seafood market, is scheduled to leave its fabled 80-year-old halls to move into bigger, more modern facilities next year ahead of the 2020 Tokyo Olympics. The outer part of the market, the Jogai Shijo, that caters to the public will stay in its old place, but critics wonder about its chances for survival without the world's biggest fish trading place at its doorsteps. (Photo by Thomas Peter/Reuters)

Fishermen collect their catch from a net at Dojran Lake, Macedonia, January 4, 2017. Fish from the lake is a traditional food for locals for orthodox Christmas eve, which falls on January 6. The lake faced sustainability issues during the 1990s due to drought and excessive use of its water but has since recovered after measures were taken to replenish and sustain water levels, according to local media. Dojran Lake is one of the three natural lakes in Macedonia, and also the warmest. It is said it is also the richest lake in fish in Europe. (Photo by Ognen Teofilovski/Reuters)

A Naga man carries fish in his teeth after it was stunned by dynamite, which fishermen threw in a creek between Donhe and Lahe township, in the Naga Self-Administered Zone in northwest Myanmar December 27, 2014. (Photo by Soe Zeya Tun/Reuters)

An alligator is skinned at All American Gator August 16, 2006 in Pembroke Park, Florida. The company processes gators for their skins, meat and trophies and was at full capacity a day after the start of gator hunting season. This year more than 4,000 licenses were sold with each license allowing hunters to kill two gators. The hunt has been expanded by 41 days over previous years, running August 15 to November 1. (Photo by Joe Raedle/Getty Images)

Tom Nevins guts a feral pig sow during hunting on Silver Plains Station on October 8, 2011 outside of Coen, Australia. Feral pigs are recognised as environmental and agricultural pests reported to have a population of up to 23.5 million over around half of Australia. The Cooktown Hog Hunt is held annually with this year's hunting window open from registration at 2pm on Friday to the end of weigh in at 2pm on Sunday afternoon. (Photo by Mark Kolbe/Getty Images)