(CNN) -- A polar bear falls through thin Arctic ice while searching for food for his family. A humpback whale guides her calf on a perilous 4,000-mile journey. A herd of African elephants in search of water battles a sandstorm in the Kalahari Desert.



"Earth," a documentary in theaters Wednesday, follows families of polar bears and other animals.



These dramatic scenes await viewers in "Earth," a feature-length documentary hitting theaters Wednesday for Earth Day.



For British filmmakers Alastair Fothergill and Mark Linfield, surveying the whole planet for Earth's most exotic species and magnificent landscapes was a daunting task.



"We wanted to tell an epic story about the whole planet," co-director Fothergill told CNN in an interview. "We spent a record 2,000 days in the field. We filmed in 46 countries worldwide, on every continent."



Fothergill and Linfield shot the footage for the film while making "Planet Earth," the Emmy-award-winning nature series that aired on the BBC and the Discovery Channel in 2007.  See photos from "Planet Earth" »



But the filmmakers say "Earth" is not just a remix of the previous project.



"The movie has over 40 percent original footage. It has a very distinctly different story line than the TV series," said Fothergill, who believes small TV screens don't do justice to the images he and Linfield captured.  Watch directors give behind-the-scenes look at 'Earth' »



"It's very hard [on TV] to give people a true sense of what it's like to be there," he said. "What we think is very special about the movie is its surround sound. When the lions roar, you get a real feeling for being there."



"Earth" is the first of a series of movies set to be released under the newly branded Disneynature label -- a spin-off of "True-Life Adventure," Disney's first nature documentary series of the '40s and '50s.



Nature movies have made a big impression on national and international audiences in recent years. The 2005 documentary "March of the Penguins" cost roughly $3 million to make and sold over $127.4 million in tickets worldwide.



Disney plans to release one feature-length film a year. The next one is "Oceans" in 2010 followed by "Big Cats" and "Chimpanzees." In honor of Earth Day 2009, Disney promised to plant a tree for each person who goes to see the movie on its opening weekend.



"Earth" examines the resilience of life in the face of ever-present danger through three stories of mothers and their young: polar bears in the Arctic, elephants in Africa's Kalahari Desert and humpback whales in the tropical oceans. Thirty-nine other exotic species from all corners of the world get supporting roles.



The film is narrated by James Earl Jones, and George Fenton composed the score, which is performed by the Berlin Philharmonic Orchestra. iReport.com: Tell us about nature and environmental issues near you



Over the course of five years, the filmmakers collected video footage from some of the most remote places on the planet, including the Aurora Australis in Antarctica, the peaks of the Himalayas, and the tropical birds of Papua New Guinea, to reveal the earth's intrinsic beauty and harsh realities.



Central to the movie's storyline is the constant tug-of-war between the animal "actors" and their ever-changing environment.  See iReporters' photos and video of local ecological issues »



"Although the elephants and the humpback whales and polar bears are the animal stars, the other big star of the movie is the earth -- the planet itself," said Fothergill. "Really the one thing that unites all of our planet and all the animals that live on it is the seasonality of it."



Without the earth's 23.5-degree tilt to the sun there would be no seasons, no variation in daylight and darkness, said Fothergill.



Fothergill and Linfield used state-of-the-art camera
Under which label is it released? What subject matter does "Earth" cover? What is the name of Disney's new label? What did Disney vow to do for everyone who sees the film opening week? What other film have the makers of "Earth" made? Who shot the documentary? What has Disney vowed? What is the "Earth" movie about?
"Earth" is the first of a series of movies set to be Earth Disneynature plant a tree "Planet Earth," Alastair Fothergill and Mark Linfield, to plant a tree for each person who goes to see the movie on its opening weekend. families of polar bears and other animals.
question: Under which label is it released?, answer: "Earth" is the first of a series of movies set to be | question: What subject matter does "Earth" cover?, answer: Earth | question: What is the name of Disney's new label?, answer: Disneynature | question: What did Disney vow to do for everyone who sees the film opening week?, answer: plant a tree | question: What other film have the makers of "Earth" made?, answer: "Planet Earth," | question: Who shot the documentary?, answer: Alastair Fothergill and Mark Linfield, | question: What has Disney vowed?, answer: to plant a tree for each person who goes to see the movie on its opening weekend. | question: What is the "Earth" movie about?, answer: families of polar bears and other animals.