A protester reacts as police use water cannon during a demonstration to demand changes in the Chilean education system in Santiago, Chile June 25, 2015. (Photo by Ueslei Marcelino/Reuters)

Demonstrators perform a dance in front of riot policemen during a march called by students to request changes in the education system in Santiago, Chile September 5, 2017. (Photo by Ivan Alvarado/Reuters)

Climate change activist Greta Thunberg reacts during a news conference during COP25 climate summit in Madrid, Spain, December 9, 2019. (Photo by Juan Medina/Reuters)

Ocean Rebellion put on a display of puking oil heads ahead of climate change conference COP26 in Glasgow, Britain, 29 October 2021. (Photo by Robert Perry/EPA/EFE)

People enjoy carnival while shouting slogans of female empowerment and anti harrassment in Sao Paulo, Brazil on January 28, 2018. The carnival is marked by a lot of fun, but also has space to talk about more serious things – without losing the good mood. Parading for the first time in São Paulo, the Vaca Profana block proposed a reflection on sieges and machismo. (Photo by Cris Faga/Rex Features/Shutterstock)

Members of the public admire trees displaying their autumn colours at the Royal Horticultural Society Garden Wisley on October 26, 2011 in Wisley, England. Many deciduous trees have now changed colour as they begin to shed their leaves for Autumn. An extended period of leaf colour change has come about this year due to a warm, dry Spring prompting an early growth spurt and a premature colour change. (Photo by Oli Scarff/Getty Images)

The photo project was done for the organization Fishlove and included some other U.K.-based celebrities posing in the buff with critters ranging from bass fish to sharks. Its goal is to raise awareness of how overfishing is destroying the oceans. The release of Gillian's nearly nude pic, which was snapped by French portrait photographer Denis Rouvre, is timed with a European Parliament vote on banning destructive forms of deep-sea fishing in the Northeast Atlantic. The Fishlove organization is trying to rally voters to sign a petition ending deep-sea trawling – which, according to scientists, is negatively impacting the fish population and their habits – and Gillian solicited signatures in a Twitter post. Photo: “Fish Love” Project by Photographer Denis Rouvre. Gillian Anderson. (Photo by Denis Rouvre)

Giant panda Meng Meng plays on a tree at a Siberian tiger-breeding base in Changchun, China on December 10, 2015. (Photo by Xu Chang/Xinhua Press/Corbis)