- Coral reefs are massive underwater formations. They develop near the surface of tropical waters within reach of the sun's rays. Coral reefs are composed of the calcified skeletons of organisms known as polyps. Polyps are small invertebrates encased in hard limestone skeletons. Coral reef formation begins when a single polyp settles on and binds its skeleton to a rock. The polyp replicates itself forming thousands of duplicates. Each new polyp binds itself to the existing colony. Over time, neighboring polyp colonies join together and form reefs. Appearing in a rainbow of colors, coral reefs are beautiful and bursting with life. These communities house an abundance of marine life including sea cucumbers, nudibranchs, sea anemones, parrot fish and giant clams.
- It has taken nature millions of years to chisel out the countless caves that appear across the planet. With their mazes of complex passageways and hidden chambers, caves possess an exotic charm all their own. Caves form largely in landscapes composed of limestone, gypsum, salt or dolomite called karst. The most common method of cave formation is the dissolution of rock by surface water sinking underground or by underground water rising to the surface. Volcanic eruptions often form caves as flowing lava cools. Caves also can appear in between rock slabs and boulder piles. Large, jagged protrusions of rock line the floors and ceilings of most caves. Those that spike down from cave ceilings are called stalactites. Those reaching up from the cave floor are called stalagmites. Cave inhabitants vary depending on the location of the cave and the amount of sunlight that it receives. Common cave dwellers include fish, salamanders, bats, crickets and bacteria.
- Rainforests appear on every continent except Antarctica. Rainforests contain an amazing abundance of life. While they make up less than 2 percent of the planet's total surface, they contain an estimated 50 percent of its plants and animals. Over 70 percent of rainforest creatures live in a layer called the canopy. The canopy consists of densely-packed tree tops towering high above the forest floor. The canopy is home to vast numbers of plant and animal species many of which science has yet to discover. Many rainforest animals spend their entire lives in the canopy without ever descending to the rainforest floor. Common canopy occupants include the toucan, sloth, cockatoo, macaw, golden lion, howler monkey and pygmy marmoset.
- Canyons are sunken valleys surrounded by steep cliffs that are carved out of the earth by bodies of water. The most well-known canyon is the Grand Canyon. Located in northwest Arizona on the Colorado Plateau, this colossal chasm was created over millions of years by the Colorado River. Among the most impressive aspects of the Grand Canyon is its sheer size. The Grand Canyon is 277 miles long, a mile deep and 18 miles across. Minerals in the rocks cover the canyon with warm, subtle shades of red, yellow, brown and green. Features in the canyon vary and include high cliffs, towering rock piles and leaning slopes. The semi-arid habitat houses a diverse array of animal life including mountain lions, eagles, elk, black bears, bobcats and spotted owls.
- The deep ocean abyss is one of the planet's last remaining frontiers. To this day, most of the abyss has yet to be explored. It is a dark and dismal environment where scientists previously believed that little life could survive. However, scientists have recently discovered that life in the abyss is not only surviving, but thriving around hydrothermal vents on the ocean floor. More than 300 different species are believed to inhabit these areas. This includes large tube worms, giant white crabs, shrimps and an array of bizarre fish that challenge even the most vivid imagination. These otherworldly organisms have evolved to contend with the harsh conditions surrounding hydrothermal vents, including poisonous gases, high acidity, massive pressure and alternating scalding hot and freezing cold temperatures.