Photo of the day

Grand Canyon National Park, Ariz. - A canny hunter - the Kit Fox. This image is from America's National Parks.

Santa Barbara, Calif.: A lobster at UC Santa Barbara. This image is from Evolution of the Eye.

New York City, N.Y.: Jason Silva preparing to ride the Backwards Bike in front of a crowd in Times Square. This image is from Brain Games.

Gates of the Arctic National Park, Alaska: A male ground squirrel, hurt by a fight with a rival. This image is from America's National Parks.

Hallo Bay, Alaska: On the lookout and protecting her cubs, this mother bear balances on her hind legs peering out over the meadow of Hallo Bay, Alaska. This image is from Grizzly Empire.

Arctic National Park, Alaska: The willow ptarmigan changes its plumage from winter to summer to be perfectly camouflaged in the Alaskan landscape. This image is from America's National Parks.

Caracal prowling through the arid Namibian Desert. This image is from Big Cats: An Amazing Animal Family.

Namibia: One female lion lying on her back with her eyes closed. This image is from Vanishing Kings: Desert Lions of the Namib.

Great Smoky Mountains National Park: The Great Smoky Mountains National Park is called salamder capitol in the world. More than 30 species inhabit the park. This image is from America's National Parks.

Every Big Cat is awesome – and each one can boast extraordinary powers. From extreme speed to bone crushing bites, Big Cats are some of the most impressive predators on the planet. Host Boone Smith creates testing challenges for these Big Cats - Cheetah’s, Tigers and Lions line up for a unique competition. This has never been tried before. Anything can happen in The Big Cat Games. This image is from Big Cat Games.

Hallo Bay, Alaska: Teaching its yearling cub how to survive not only means providing milk and physical protection, but this mother bear also plays with the little one to strengthen and get it ready for a solitary life post cubhood. This image is from Grizzly Empire.

Yellowstone National Park: Yellowstone is the oldest National Park in the USA - home to large wild bison herds that roam the plains. This image is from America's National Parks.

New York City, N.Y.: Jason Silva with Marc Salem in Times Square. This image is from Brain Games.

Everglades National Park, FLA.: A female alligator makes her way through her self-built waterhole. This image is from America's National Parks.

The cave dwelling Pallas Cat. This image is from Big Cats: An Amazing Animal Family.

Saguaro National Park, Arizona: Young antelope squirrels play with each other. This image is from America's National Parks.

Santa Barbara, Calif.: Some star fish in a tide pool at UC Santa Barbara. This image is from Evolution of the Eye.

Great Smoky Mountains National Park: Elk have been reintroduced to the National Park and are thriving now again. This image is from America's National Parks.

Tigers wrestle in the water. Tigers usually live 8 to 10 years in the wild. This image is from Cat Fight.

Yellowstone National Park: The Grizzly is the apex predator of the Yellowstone National Park. This image is from America's National Parks.

London: Host Jason Silva during a game to test reflexes. This image is from Brain Games.

Olympic National Park: The Pacific Ocean along coast of the Olympic National Park are an underwater haven for countless species. This image is from America's National Parks.

The Siberian tiger is the largest and palest subspecies of tiger. This image is from Cat Fight.

Grand Canyon National Park, Ariz.: Winter is a peaceful time in the Grand Canyon National Park. This image is from America's National Parks.

Lake Kariba Matusadona National Park Zimbabwe, Africa: Eastern Pride makes a big leap over a creak fearing a croc that was patrolling about 10 meters away. This image is from The Lakeshore Killers.

Grand Canyon National Park, Ariz.: The Colorado Plateau is known for heavy thunderstorms. This image is from America's National Parks.

Young male tiger scratching sharp claws down tree trunk. This is a way of marking a territory. This image is from Tiger on the Run.

Young males have to leave the pride after 2-3 years whilst lionesses stay their whole live in their family. This image is from Pride.

Yosemite National Park, Calif.: The Yosemite National Park covers an area of more than 1,200 square miles. This image is from America's National Parks.