A gory fight to the death between snarling dogs and captured wild boars. Gathered around a bamboo-walled arena, Indonesians in this remote part of Java island seem eager to watch the blood-curdling contests, known locally as “adu bagong” (boar fighting). Not surprisingly, animal rights activists are up in arms against the regular spectacle, which began in the 1960s when wild pig numbers in this area in West Java soared and they were hunted to protect crops. Here: Women share a joke as they walk to a paddy field in Cikawao village of Majalaya, West Java province, Indonesia, October 12, 2017. (Photo by Reuters/Beawiharta)

Matador Marco Espinola, who emigrated from the Azores two years ago, challenges a bull during an Azorean “tourada a corda” (bullfight by rope) in Brampton, Ontario August 15, 2015. Bulls in a tourada a corda are held by a rope controlled by a team of men to make sure the animal does not cause injury. Bulls are never killed, in contrast with bullfighting in Spain. The Portuguese population in Canada, numbering 429,000 in the 2011 census, mainly centers around Toronto with immigrants from the nine islands of the mid-Atlantic Azores archipelago. (Photo by Chris Helgren/Reuters)

“NASA's Pathfinder, Pathfinder Plus, Centurion and Helios Prototype were an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as “atmospheric satellites”, to perform atmospheric research tasks as well as serve as communications platforms”. – Wikipedia

Photo: The solar-electric Helios Prototype flying wing is flies over the Hawaiian islands of Niihau and Lehua during the first solar-powered test flight July 14, 2001 from the U.S. Navy's Pacific Missile Range Facility on Kauai, HI. The 18-hour flight was a functional checkout of the aircraft's systems and performance in preparation for an attempt to reach sustained flight at 100,000 feet altitude later in the summer. (Photo Courtesy of NASA/Getty Images)

“Nomascus is the second most speciose genus of gibbons (family Hylobatidae). Originally this genus was a subgenus of Hylobates, and all individuals were considered one species, Hylobates concolor. Species within Nomascus are characterized by 52 chromosomes. Some species are all black, some light with a distinct black tuft of crown fur, and some by distinct, light-colored cheek patches. Nomascus is found from southern China (Yunnan) to southern Vietnam, and also on Hainan Island. One of the genus' species, Nomascus nasutus, has been deemed “the most critically endangered ape species in the world”. All of the species in this genus are endangered or critically endangered”. – Wikipedia

Photo: A newborn White-Cheeked Gibbon clings to its mother in the Nanning Zoo on April 12, 2004 in Nanning, Guangxi province, China. The White-Cheeked Gibbon's natural habitat is Southern China as well as Vietnam and Laos. They are classified as highly endangered and are on the brink of extinction due to poaching and reduction of natural rainforests. (Photo by Getty Images)

The Haʻikū Stairs, also known as the Stairway to Heaven or Haʻikū Ladder, is a steep hiking trail on the island of Oʻahu. The trail began as a wooden ladder spiked to the cliff on the south side of the Haʻikū Valley. It was installed in 1942 to enable antenna cables to be strung from one side of the cliffs above Haʻikū Valley to the other. A building to provide a continuous communication link between Wahiawā and Haʻikū Valley Naval Radio Station was constructed at the peak of Puʻukeahiakahoe, elevation about 2,800 feet (850 m). The antennae transmitted very low frequency radio signals from a 200,000-watt Alexanderson alternator in the center of Haʻikū valley. The signals could reach US Navy submarines as far away as Tokyo Bay while the submarines were submerged.

The Al-Gaffal is an annual long-distance race between crews sailing 60-ft. traditional wooden boats called dhows and takes place in the Persian Gulf, between the island of Sir Bu Nair, near the Iranian coast and the Gulf emirate of Dubai. Photo: Traditional wooden boats, or dhows, compete at sunrise during the Al Gaffal race, a long-distance dhow sailing race, near Sir Bu Nuayr, near Sharjah May 18, 2014. (Photo by Martin Dokoupil/Reuters)

Todd Bretl specializes in underwater photography, and is able to capture striking photos of aquatic life big and small. His photos of sharks are particularly striking; though he rarely faces hostility from the animals, he tries not to spend too much time looking through his viewfinder and many shots are framed by educated guesses and impeccable timing. What follows are photographs taken over the past several years on trips to the Bahamas and Isla Guadalupe, an island off the coast of the Baja California peninsula in Mexico. (Photo by Todd Bretl)

These are the chimp-ly marvellous images captured by a cheeky monkey after turning the tables on a photographer who left his camera unmanned. The inquisitive scamp playfully went to investigate the equipment before becoming fascinated with his own reflection in the lens. And it wasnt long before the crested black macaque hijacked the camera and started snapping away sending award-winning photographer David Slater bananas. David, from Coleford, Gloucestershire, was on a trip to a small national park north of the Indonesian island of Sulawesi when he met the incredibly friendly bunch. (Photo by David Slater/Caters News)