A Flame Skimmer or Firecracker Skimmer dragonfly (Libellula saturata) rests on a small branch in Topanga, California, USA, 18 June 2018. The Flame Skimmer dragonfly is found in the Western United States near ponds and creeks. (Photo by Mike Nelson/EPA/EFE)

Children hold signs thanking truck drivers hauling rocks to the Lake Oroville Dam after an evacuation was ordered for communities downstream from the dam in Oroville, California, U.S. February 13, 2017. (Photo by Jim Urquhart/Reuters)

The Doppler on Wheels (DOW) vehicle scans a supercell thunderstorm during a tornado research mission, May 8, 2017 in Elbert County near Agate, Colorado. Doppler on Wheels (DOW) is a mobile doppler radar mounted on a truck that brings instruments directly into storms, allowing scientists to scan storms and tornadoes and make 3-D maps of wind and debris. (Photo by Drew Angerer/Getty Images)

In a picture taken with an underwater camera, a couple stands in front of a Polynesian priest during their underwater wedding ceremony on October 25, 2014 in Bora-Bora, in French Polynesia. The ceremony lasts twenty minutes and costs around 2700 euros. (Photo by Ben Thouard/AFP Photo)

Against the scorching sun, a hungry jackal chases a flock of birds looking for a quick morning snack. Taken in South Africa's Kgalagadi Transfrontier National Park, these images capture the moment a lone hunter tries, and then succeeds, in his pursuit. (Photo by John Mullineux/Solent News)

Krista Long began snapping pics of people sliding down a water slide after many visits to the local water park with her tween daughters. The result is an action-packed series that show emotions ranging, she says, “from pure joy to fear, in anticipation of the inevitable splash-down!” (Photo by Krista Long)

The pugs dressed in Parka jackets in Sonoma County, California. (Photo by Phillip Lauer/Barcroft Media)

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)