Capybaras bathe in the hot spring water at the Saitama Children's zoo in Higashi Matsuyama city, Saitama prefecture on December 25, 2013. 13 capybaras in the zoo, originally from South America, enjoyed the hot spring water. (Photo by Toshifumi Kitamura/AFP Photo)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)

An Indian Sikh Nihang, or warrior, performs Gatka martial arts skills during a procession at the Golden Temple in Amritsar on January 6, 2014, as part of birth anniversary celebrations of Guru Gobind Singh. The birth anniversary of Guru Gobind Singh, the tenth Sikh guru, is marked on January 6. (Photo by Narinder Nanu/AFP Photo)

Members of the Al-Baraa bin Malek batallion, part of the Free Syria Army's Al-Fatah brigade, duck to the ground as they pull a man (R) who was shot by a sniper twice in the Bustan al-Basha district of the northern city of Aleppo on October 20, 2012. (Photo by Javier Manzano/AFP Photo)

Bangladeshi railway police try to clear line, as thousands of Bangladeshi Muslims gather to board trains to return home after attending three-day Islamic Congregation on the banks of the River Turag in Tongi, 20 kilometers (13 miles) north of the capital Dhaka, Bangladesh, Sunday, January 26, 2014. (Photo by A. M. Ahad/AP Photo)

While vacationing on the Maldives Islands, Taiwanese amateur photographer Will Ho stumbled onto an incredible stretch of beach covered in millions of bioluminescent phytoplankton. These tiny organisms glow similarly to fireflies and tend to emit light when stressed, such as when waves crash or when they are otherwise agitated. While the phenomenon and its chemical mechanisms have been known for some time, biologists have only recently began to understand the reasons behind it. Photo: Bioluminescent phytoplankton washes up on Maldives beach. (Photo by Will Ho)

Participants struggle to reach the prizes during a greased-pole climbing competition held as a part of the independence day celebrations in Jakarta, Indonesia, Sunday, August 17, 2014. Indonesia is celebrating its 69th independence from the Dutch colonial rule. (Photo by Dita Alangkara/AP Photo)

Rick Sorenson, owner of the Rio Ramaza Marina, wades in the Sacramento River after securing an old paddlewheel boat on his property as the river makes its way up the levee on Garden Highway in Sacramento, Calif., Monday, January 9, 2017. (Photo by Hector Amezcua/The Sacramento Bee via AP Photo)