Shooting star by Tony Wu, US/Japan. Winner, underwater. The electrifying reproductive dance of a giant sea star. As the surrounding water filled with sperm and eggs from spawning sea stars, Wu faced several challenges. Stuck in a small, enclosed bay with only a macro lens for photographing small subjects, he backed up to squeeze the undulating sea star into his field of view. The dancing posture of spawning sea stars rising and swaying may help release eggs and sperm, or may help sweep the eggs and sperm into the currents where they fertilise together in the water. Kinko Bay, Japan. (Photo by Tony Wu/Wildlife Photographer of the Year)

“Echus Chasma is a chasma in the Lunae Planum high plateau north of the Valles Marineris canyon system of Mars. Clay has been found in Echus Chasma that means that water once sat there for a time. Echus Chasma is approximately 100 km long and 10 km wide, with valleys ranging in depth from around 1 km to 4 km”. – Wikipedia

Photo: In this handout image supplied by the European Space Agency (ESA) on July 16, 2008, The Echus Chasma, one of the largest water source regions on Mars, is pictured from ESA's Mars Express. The data was acquired on September 25, 2005. The dark material shows a network of light-coloured, incised valleys that look similar to drainage networks known on Earth. It is still debated whether the valleys originate from precipitation, groundwater springs or liquid or magma flows on the surface. (Photo by ESA via Getty Images)

A group of young men use a selfie stick to take a picture of themselves in shallow waters known as the first cataract of the River Nile outside Khartoum, Sudan, May 22, 2015. In Sudan, which faces insurgences in the western region of Darfur and along its border with breakaway South Sudan, as well as double-digit inflation and high unemployment, life goes on for young people in the capital Khartoum. (Photo by Mohamed Nureldin Abdallah/Reuters)

A fisherman boats in Chao Lake where thick cyanobacteria gather on the surface on August 5, 2015 in Chaohu, Anhui Province of China. As high temperature came in summar, part of water in Anhui Province's Chao Lake breeds large tracts of cyanobacteria which not only brought pollution to sense of smell, but also affected people's life. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

A municipal police officer throws a stone back at protesting residents of Kampung Pulo after clashes erupted during an eviction in Jakarta, Indonesia, August 20, 2015 in this photo taken by Antara Foto. Residents facing eviction from a flood-prone part of Indonesia's capital of Jakarta clashed with police on Thursday, prompting security forces to fire tear gas and water cannon. (Photo by Muhammad Adimaja/Reuters/Antara Foto)

South Korean traditional bow artisan Kwon Yeong-Hak works on a bow in his workshop in Yecheon-gun, Gyeongsangbuk-do, South Korea, 26 February 2015. Kwon Yeong-Hak still crafts his bows in the traditional way, carrying on a four-generation family business. The Gakgung bow, of which Kwon is one of the last remaining artisans, is unique to Korea, and is constructed with a variety of materials, including water buffalo horn, oak, bamboo and cattle spinal sinew. A ban on the import of water buffalo horns has put the Gakgung tradition at risk. (Photo by Jeon Heon-Kyun/EPA)

Photographer Lucy Ray says she has been scratched by the pooches who are diving underwater to try and catch a tennis ball. Their wide-eyed desperation has been captured by a specialist underwater photographer who admits she has been bitten and scratched by the pooches who only had eyes for the ball. Lucy Ray, 34, said: “A dog could have the cutest face on land but as soon as they get in the water they can be terrifying. Their eyes bulge and teeth shoot out of their mouth just like an alien as they try to catch the ball”. (Photo by Lucy Ray)

“El rio mas bonito del Mundo”, the most beautiful river of the world, the “River of five colors”, the “Rainbow River”, or even the “Escaped from Paradise”, are the shimmering appellations that Colombians give to Cano Cristales, a small stream located in the heart of the Macarena National Park, 150 km (93 miles) south of Bogota. Photo: A waterfall is seen at the end of the rainy season, in August, when the water level finally decreases, in the Cano Cristales RIver in the Sierra de la Macarena in Colombia. It has become covered with a bright pink endemic aquatic plant, Macarenia Clavigera. (Photo by Olivier Grunewald)