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)

A huge atlas moth, with a wingspan of more than 9in, photographed on an areca nut plantation in Sirsi, India. (Photo by Uday Hegde/Close Up Photographer of the Year)

People board a train at the West Railway Station on January 7, 2012 in Beijing, China. China's railways are bracing themselves as millions of migrant labourers are set to leave cities for their native villages to celebrate the Chinese New Year. (Photo by Lintao Zhang/Getty Images)

Brad Snead walks past melting ice on the Cook Inlet beach, Saturday, March 26, 2011, in Kenai, Alaska, while looking for agates. (AP Photo/Peninsula Clarion, M. Scott Moon)

A man sits under lanterns and decorations on a street ahead of the Chinese Lunar New Year in Chinatown Yangon, Myanmar January 23, 2017. (Photo by Soe Zeya Tun/Reuters)

A Thai and foreign revelers battle with water guns during the annual Songkran celebration at Khaosan Road, a tourist spot in Bangkok, Thailand, 12 April 2017. The four southeast Asian nations of Myanmar, Thailand, Cambodia and Laos started the Buddhist new year, known as Thingyan in Myanmar and Songkran in Thailand, on April 13. (Photo by Rungroj Yongrit/EPA)

Rebecca Smith poses for a photograph during winter solstice with her Irish Wolfhound dog called Amazing Grace at the 5000 year old stone age tomb of Newgrange (not in view) in the Boyne Valley at sunrise in Newgrange, Ireland, December 21, 2016. (Photo by Clodagh Kilcoyne/Reuters)

A Nepalese Gurung community woman, wearing traditional attire, prepares to participate in a parade to mark their New Year known as “Tamu Loshar” in Kathmandu, Nepal, Friday, December 30, 2016. The indigenous Gurungs, also known as Tamu, are celebrating the advent of the year of the bird. (Photo by Niranjan Shrestha/AP Photo)