The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

Lance Cpl. Blas Trevino of the 1st Battalion, 5th Marines, shouts out as he is rescued on a medevac helicopter from the U.S. Army's Task Force Lift “Dust Off”, Charlie Company 1-214 Aviation Regiment after he got shot in the stomach outside Sangin, in the Helmand Province of southern Afghanistan on June 11, 2011. The Army's 'Dust Off' crew needed two attempts to get him out, as they were fired upon and took five rounds of bullets into the tail of their aircraft. (Photo by Anja Niedringhaus/AP Photo/File)

Situated in the Pacific Ocean some 620 miles (1,000 km) from the South American continent, these 19 islands and the surrounding marine reserve have been called a unique “living museum and showcase of evolution”. Photo: “Close-up. We had a juvenile Red-Footed Booby come visit us on the sun deck. I got some closeups with my ultrawide 11-16mm Tokina”. (Photo by Carl Fredrickson)

It's that time of year again when dogs with unusually large heads, hairless bodies and other oddities compete to be the World's Ugliest Dog. This year's winner? A 2-year-old mutt named Peanut, whose wild white and brown hair, bulging eyes and protruding teeth belie his sweet, energetic personality. Peanut's owner, Holly Chandler of Greenville, North Carolina, says he was seriously burned as a puppy and she wants to use her pet to raise awareness about animal abuse. She plans to use the $1,500 prize to pay for other animals' veterinary bills. The contest, held at the Sonoma-Marin Fairgrounds in Petaluma, California, is in its 26 year. The dogs are scored by a three-judge panel in several categories, including special or unusual attributes, personality and natural ugliness.

“The giant clam, Tridacna gigas (known as pā’ua in Cook Islands Māori), is the largest living bivalve mollusc. T. gigas is one of the most endangered clam species. It was mentioned as early as 1825 in scientific reports. One of a number of large clam species native to the shallow coral reefs of the South Pacific and Indian oceans, they can weigh more than 200 kilograms (440 lb) measure as much as 120 cm (47 in) across, and have an average lifespan in the wild of 100 years or more”. – Wikipedia

Photo: Tridacna Gigas, or Giant Clams spew water as a traditional fisherman passes by a small sanctuary on January 23, 2004 near Bolinao in the Northern Philippines. The clams, prime builders for coral reefs and providing shelter for spawning fish and other marine life, are exposed by low tides in the sanctuary. Overfishing and pollution throughout the country are not only threatening food security, but are also starting to choke one of the few working clam sanctuaries in the world. (Photo by David Greedy/Getty Images)

Guardian of the Mangroves – Overall Winner. Tanya Houppermans, Cuba. A curious American crocodile (Crocodylus acutus) swims right up to Tanya, at Gardens of the Queen (Jardines De La Reina), an archipelago off the coast of Cuba. It has been strictly protected since 1996, and is one of the most untouched marine ecosystems in the world. ‍ “The healthy population of American crocodiles is down to the pristine condition of the mangroves and I wanted to capture close ups of this gentle giant in its natural habitat. I hope this image can illustrate that protecting areas like this is so critical”. (Photo by Tanya Griffin Houppermans/Mangrove Photographer of the Year)

HMS Dragonís Mk8 Lynx Helicopter conducted day into night flying serial by L(Phot) Dave Jenkins which won the Media Operations Category which was awarded to the best single image that is judged to create the most impact as a news in the annual Peregrine Trophy awards. (Photo by Dave Jenkins/PA Wire)

A girl paddles on her stand-up board on the waters of Guanabara bay at Bica beach in Rio de Janeiro Brazil, January 10, 2016. Few features capture the beauty, or the problems, of one of the world's most dramatic urban landscapes like Guanabara Bay - the finger-like inlet that forms the shoreline and harbor for Rio de Janeiro. The bay, which carves into southeast Brazil from the Atlantic Ocean, literally gave Rio its name when Portuguese mariners mistook it for a “rio”, or “river”. Four centuries later, the bay is preparing to welcome another sort of seafarer – Olympic sailors, who will navigate the bay when the 2016 Rio Olympics kick off in August. (Photo by Ricardo Moraes/Reuters)