A Hawaiian cleaner wrasse provides its cleaning services to a yellowfin goatfish in a reef community off the Big Island in Hawaii. Cleaner species help rid their hosts of ectoparasites, dead tissue, bacteria and fungi. Studies have shown cleaning to play a vital role in keeping many reef ecosystems healthy. (Photo by Marty Snyderman/Caters News Agency)

Syrian Internal Security Forces dance in celebration during their graduation ceremony, at Ain Issa desert base, in Raqqa province, northeast Syria, Thursday, July 20, 2017. Some 250 residents of Syria's Raqqa province are the latest batch to graduate from a brief U.S-training course that is preparing an internal security force to hold and secure areas as they are captured from Islamic State militants. (Photo by Hussein Malla/AP Photo)

Huang Wensi in action during her final training session in Ningbo, Zhejiang province, China, before she heads to Taiwan for her Asia Female Continental Super Flyweight Championship match, September 23, 2018. Huang is one of a small but growing number of women in China to embrace professional boxing, relishing its intense nature despite traditional stereotypes that steer women away from such activities. “A women is not just limited to being a wife or mother in the house”, she said. (Photo by Yue Wu/Reuters)

Young dancers from the Style Dance Academy perform during a Mother's Day block party in Caracas, Venezuela, Sunday, May 19, 2019. Although Mother's Day was officially celebrated the previous weekend, people in the Petare area organized the neighborhood party to celebrate the mothers of their community. (Photo by Rodrigo Abd/AP Photo)

Children jump into the water despite strong waves after a strong downpour at Manila's bay, Philippines, Wednesday, July 17, 2019. Schools in metropolitan Manila have been suspended as Tropical Storm Danas, locally named Falcon, continue to enhance the southwest monsoon as it maintains its strength bringing heavy rains over parts of Luzon and Visayas according to the Philippine Atmospheric Geophysical and Astronomical Services Administration. (Photo by Aaron Favila/AP Photo)

A commercial airline landing at the Princess Juliana International Airport in St Maarten on July 9, 2018. Ukrainians Oleg Kolisnichenko, 36, and Yulia Nos, 25, have been blasted for the “stupid stunt” on Maho Beach, which lies next to the main airport on the Caribbean island of Saint Martin. The stunt was met with criticism rather than praise from social media users. (Photo by SWNS: South West News Service)

A coil-shaped Helix Nebula showing a fine web of filamentary “bicycle-spoke” features embedded in the colorful red and blue ring of gas. At 650 light-years away, the Helix is one of the nearest planetary nebulae to Earth. A planetary nebula is the glowing gas around a dying, Sun-like star. (Photo by Reuters/NASA)

Lazar and his sister Andjelka sit by a candle in their home in the eastern Serbian town of Majdanpek, December 4, 2014. Electricity workers in Serbia struggled through snow, ice and treacherous terrain on Thursday to restore electricity to an eastern town left shivering without power, heating or running water for a fourth day. (Photo by Marko Djurica/Reuters)