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)

A picture taken with slow shutter speed shows members of the group “The Kattfiller” from Attendorn taking part during the Norddeutsche Championship carnivalesque dance sport in Kassel (Hessen), Germany, 28 February 2016. About 1,100 qualified dancers show in different disciplines their skills. (Photo by Swen Pfoertner/EPA)

A sunflower “smiles” in a field in Tokyo on August 7, 2014. Some 20,000 sunflowers were enjoyed by visitors to the area this week. (Photo by Yoshikazu Tsuno/AFP Photo)

Global wildlife populations will decline by 67% by 2020 unless urgent action is taken to reduce human impact on species and ecosystems, warns the biennial Living Planet Index report from WWF (World Wide Fund for Nature) and ZSL (Zoological Society of London). From elephants to eels, here are some of the wildlife populations most affected by human activity. Here: The maned wolf is among the large mammals in the Brazilian Cerrado that are threatened by the increasing conversion of grasslands into farmland for grazing and growing crops. (Photo by Ben Cranke/Nature Picture Library/Alamy Stock Photo)

A fox cub with some bluebells in some woodland at Wye Valley near Gloucester, United Kingdom on April 29, 2023. (Photo by Thomas Winstone/Picture Exclusive)

Female members of the PDI (Investigations Police of Chile) march during the traditional military parade as part of the independence day celebrations on September 19, 2021 in Santiago, Chile. This year the militar parade was celebrated with 30% of the staff present in pre-pandemic years. About 6,500 members of the Army, Navy, Air Force, Carabineros and PDI paraded. (Photo by Matias Basualdo/ZUMA Press Wire/Rex Features/Shutterstock)

A woman participates in a ritual for the African sea goddess Yemanja at Ramirez Beach in Montevideo, Uruguay, Tuesday, February 2, 2021. (Photo by Matilde Campodonico/AP Photo)

Katelin Wie Qi Heng of Team Singapore competes with ball during the Team Final and Individual Qualification on day seven of the Birmingham 2022 Commonwealth Games at Arena Birmingham on August 04, 2022 in Birmingham, England. (Photo by Elsa/Getty Images)