Yva Momatiuk & John Eastcott / Northern Fur Seal (Callorhinus ursinus) cross-section of seal fur shows dense growth of about 300, 000 hairs per square inch, St Paul Island, Pribilof Islands, Alaska

Yva Momatiuk & John Eastcott / Slot Canyon shaped by sand, boulders and rushing water, Arizona

Yva Momatiuk & John Eastcott / Slot Canyon shaped by sand, boulders and rushing water, Arizona

Yva Momatiuk & John Eastcott / Autumn reflections in water, Sawkill Creek, Montgomery Place Historical Park, Hudson River Valley, New York

Tim Fitzharris / Rocky Mountain Bee Plant (Cleome serrulata) flower, Great Sand Dunes National Monument, Colorado

Yva Momatiuk & John Eastcott / Quaking Aspen (Populus tremuloides) trees in autumn color, view looking up, Fairbanks, Alaska

Konrad Wothe / Ripples and reflections on water surface, Alaska

Gerry Ellis / Red Alder (Alnus rubra) and Vine Maple (Acer circinatum) reflection in quiet waters of Upper Necanicum River, Tillamook State Forest, Oregon

Konrad Wothe / Dry and cracked ground pattern, California

Michael Quinton / Western Sandpiper (Calidris mauri) flock flying during spring migration stop-over at the Copper River Delta, Alaska

Norbert Wu / Waves as seen from underwater, Maui, Hawaii

Norbert Wu / Sun's rays through clear waters of the open oceans, Hawaii

Jim Brandenburg / Mexican Golden Poppy (Eschscholzia glyptosperma) field, Organ Pipe Cactus National Monument, Arizona

Jim Brandenburg / Red Pine (Pinus resinosa) bark detail, Minnesota

Mark Moffett / Douglas Fir (Pseudotsuga menziesii) canopy, Wind River, Washington

Jim Brandenburg / Prairie Coneflower (Ratibida pinnata), South Dakota

Jim Brandenburg / Timber Wolf (Canis lupus) looking through foliage, Superior National Forest, Minnesota

Michael Quinton / Fern detail showing spore sacks

Jim Brandenburg / American Black Duck (Anas rubripes) and Mallard (Anas platyrhynchos) flock on surface of algae covered lake, Minnesota

Jim Brandenburg / Woodland Caribou (Rangifer tarandus caribou) in motion, Minnesota Zoo, Minnesota

Jim Brandenburg / Birch (Betula sp) trees, Moose Lake, Boundary Waters Canoe Area Wilderness, Minnesota

Jim Brandenburg / Showy Lady's Slipper (Cypripedium reginae) orchid, Northwoods, Minnesota

Jim Brandenburg / Sunlight filtering through trees, Minnesota

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) tail, Hawaii

Jim Brandenburg / Timber Wolf (Canis lupus) running through trees, Minnesota

Yva Momatiuk & John Eastcott / Sugar Maple (Acer saccharum) tree with snow, Hurley, New York

Yva Momatiuk & John Eastcott / Maple (Acer sp) trees in autumn, Chapel Hill, North Carolina

Yva Momatiuk & John Eastcott / Dwarf Cypress (Taxodium sp) trees reflected in water, Pine Tree Creek, Goodale State Park, South Carolina

Yva Momatiuk & John Eastcott / Dwarf Cypress (Taxodium sp) trees reflected in water, Pine Tree Creek, Goodale State Park, South Carolina

Yva Momatiuk & John Eastcott / Dwarf Cypress (Taxodium sp) trees reflected in water, Pine Tree Creek, Goodale State Park, South Carolina

Yva Momatiuk & John Eastcott / Sandstone hills along lake, Lake Powell, Glen Canyon National Recreation Area, Utah

Yva Momatiuk & John Eastcott / Lake reflecting cumulus clouds, Lake Powell, Glen Canyon National Recreation Area, Utah

Yva Momatiuk & John Eastcott / California False Hellebore (Veratrum californicum) frost-covered leaves, Payette River, Idaho

Yva Momatiuk & John Eastcott / Balsam Poplar (Populus balsamifera) leaves, Grand Teton National Park, Wyoming

Yva Momatiuk & John Eastcott / Reeds reflected in water, Kabetogama Lake, Voyageurs National Park, Minnesota

Jeff Foott / Leaves and needles in autumn, Duck Brook, Acadia National Park, Maine

Jeff Foott / Painted Hills, John Day Fossil Beds National Monument, Oregon

Jeff Foott / Painted Hills, John Day Fossil Beds National Monument, Oregon

Kevin Schafer / Rock in creek, Flume Canyon, White Mountains, New Hampshire

Jeff Foott / Hoodoos, Devil's Garden, Grand Staircase-Escalante National Monument, Utah

Jeff Foott / Calf Creek Falls, Grand Staircase-Escalante National Monument, Utah

Jeff Foott / Boulder and Circle Cliffs, Grand Staircase-Escalante National Monument, Utah

Jeff Foott / Calf Creek Falls, Grand Staircase-Escalante National Monument, Utah

Daniel J. Cox / Quaking Aspen (Populus tremuloides) trees in autumn, Colorado

Daniel J. Cox / Oxbow Bend at sunset, Snake River, Grand Teton National Park, Wyoming

Benjamin Olson / Canoe on lake, Superior National Forest, Minnesota

Jeff Foott / Trumpeter Swan (Cygnus buccinator) group flying, Grand Teton National Park, Wyoming

Matthias Breiter / Taiga and mountains, Noatak River, Noatak National Preserve, Alaska

Matthias Breiter / Hills around Kokolik River, National Petroleum Reserve, Alaska

Matthias Breiter / Hills around Kokolik River, National Petroleum Reserve, Alaska

Jim Brandenburg / Birch (Betula sp) trees, Minnesota

Jim Brandenburg / White-tailed Deer (Odocoileus virginianus) skeleton, Minnesota

Jim Brandenburg / Tangled branches in pond, Minnesota

Jim Brandenburg / White-tailed Deer (Odocoileus virginianus) pair grooming, Minnesota

Tim Fitzharris / Oak (Quercus sp) and Hickory (Carya sp) forest along creek in autumn, Ozark-Saint Francis National Forest, Arkansas

Jim Brandenburg / Anemone (Anemone sp) flowers

Albert Lleal / Western Diamondback Rattlesnake (Crotalus atrox) head scales, Barker Canyon Road, Grand Coulee, Grant County, Washington. SEM 21x

Ingo Arndt / Grand Prismatic Pool, Midway Geyser Basin, Yellowstone National Park, Wyoming

Tom Vezo / Sandstone walls, Antelope Canyon, Arizona

Piotr Naskrecki / Horseshoe Crab (Limulus polyphemus) group crawling ashore during high tide to lay their eggs, New Jersey

Piotr Naskrecki / Horseshoe Crab (Limulus polyphemus) during high tide, New Jersey

Piotr Naskrecki / Fern leaves, Estabrook Woods, Massachusetts

Piotr Naskrecki / Fern leaves, Estabrook Woods, Massachusetts

John Cancalosi / Close-up of oil shale showing sedimentation lines. Used as a fuel. Western Colorado, USA

Murray Cooper / Frozen pond, Yosemite National Park, California

Jim Brandenburg / Violet Wood Sorrel (Oxalis violacea), tallgrass prairie, Minnesota.

Suzi Eszterhas / Lace Hedgehog Cactus (Echinocereus reichenbachii) flower detail showing pistil and stamens, Red Corral Ranch, Texas

Yva Momatiuk & John Eastcott / Cottonwood tree branches against sandstone walls, Grand Staircase-Escalante National Monument, Utah

Yva Momatiuk & John Eastcott / Eroded sandstone ridges near Zabriskie Point, Death Valley National Park, California

Norbert Wu / Wave breaking as seen from underwater, North Shore, Oahu, Hawaii

Norbert Wu / Wave breaking as seen from underwater, North Shore, Oahu, Hawaii

Andy Reisinger / Waterfall detail, Yosemite National Park, California

Yva Momatiuk & John Eastcott / Close-up of intricate patterns of eroded sandstone cliffs in a small canyon near Churchwells, noon, Utah

Tim Fitzharris / Ocean waves, Hawaii

Jim Brandenburg / Fresh ice on Moose Lake, Boundary Waters Canoe Area Wilderness, Minnesota

Jim Brandenburg / Reflection of trees in Lindsey Pond with lily pads, Boundary Waters Canoe Area Wilderness, Minnesota

Jim Brandenburg / Ice and crashing wave along Shovel Point, Lake Superior, Minnesota

Winfried Wisniewski / Orchid (Epidendrum latilabre) close up, Botanical Garden of Oahu, Hawaii

Jim Brandenburg / Waterfall at twilight, Northwoods, Minnesota

Konrad Wothe / Ripples and reflections on water surface, Alaska

Matthias Breiter / Raindrops on spider web, Healy, Alaska

Konrad Wothe / American Alligator (Alligator mississippiensis) floating at water surface at sunset, Florida

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) singer view through water surface, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 987

Jim Brandenburg / Sunlight illuminating man and trees, Minnesota

Jim Brandenburg / Sunlight illuminating man and trees, Minnesota

Jim Brandenburg / First snow over birch trees, Northwoods, Minnesota

Jim Brandenburg / Desert flowers, Organ Pipe Cactus National Monument, Arizona

Michael Quinton / Wind patterns in snow, Idaho

Michael Quinton / Ice crystals on frozen creek, Wrangell-St Elias National Park, Alaska

Jim Brandenburg / Grass in Burntside River, Superior National Forest, Minnesota

Jim Brandenburg / Judd Creek rapids, Northwoods, Minnesota

Jeff Foott / Coastline, Acadia National Park, Maine

Jeff Foott / Mineral stained wall, Pictured Rocks National Lakeshore, Michigan

Jeff Foott / Venus and moon at sunset, Arizona

Jeff Foott / Rock formations, Lower and Middle Cathedral Rocks, Yosemite National Park, California

Jeff Foott / Mountain Dogwood (Cornus nuttallii) flowering over river reflection, Merced River, Yosemite National Park, California