Around 70% of the Earth’s surface is covered by oceans and those oceans hold about 96.5% of all of Earth’s water. Oceans contain the greatest diversity of life on Earth. From the freezing polar regions to the warm waters of the tropics and deep sea hydrothermal vents to shallow seagrass beds, marine organisms abound. The near-shore areas of the continental shelves are called ocean margins. Ocean margins contain a variety of habitats. Habitats are areas of the environment where a plant or animal normally lives. Temperature, ocean depth, and distance from the shore determine the types of plants and animals living in a particular habitat.

Coral reefs are a type of ocean margin habitat. Mangroves are shrub and tree species that grow When tiny animals called polyps die, their in thick clusters along ocean shores, rivers, and skeletons harden so other polyps can live on top estuaries in the tropics and subtropics. of them. Then those polyps die, and more move Mangroves are remarkably tough. Most live on in. After thousands of years, this becomes a huge muddy soil, but some also grow on sand, peat, structure called a coral reef that provides food and coral rock. They live in water up to 100 times and shelter for many kinds of ocean animals. saltier than most other plants can tolerate. They Corals reefs have been called the rain forests of thrive despite twice-daily flooding by ocean tides; the sea because of the wide variety of animals even if this water were fresh, the flooding alone found there. Animals like seahorses, clownfish, would drown most trees. Growing where land and sea turtles all live on coral reefs. Corals and water meet, mangroves bear the brunt of themselves are animals! They grab food from the ocean-borne storms and hurricanes. Mangrove water using tiny tentacle-like arms. forests are a type of estuary.

Rocky shore ecosystems, such as tide pools, are Kelp forests are coastal habitats found found along rocky coasts. Changing tides cause worldwide along the coastlines of the Pacific rocky shore areas to be completely covered and Antarctic Oceans and provide food and with water at certain times of the day and shelter for marine life. These large, brown, completely exposed to the air and sunlight at rubbery plants have hollow, globe-shaped others. growths on the leaves called pneumatocysts Changing tides make the rocky shore a difficult that help the plants rise to the surface. Giant place to live. During low tide, some areas of the kelp can grow as much as 50 centimeters (20 rocky shore are completely exposed to the air or inches) per day. They provide a safe habitat are trapped in areas of water left behind called that supports a large food web. Kelp forest food tide pools. During high tide, the rocky shore is webs include sea lions, whales, shore birds, and completely submerged underwater. other ocean animals make meals of the smaller critters that hide in the leaves.

Some ocean habitats aren’t actually in the ocean, Sandy shores are low-lying areas made up of such as estuaries. Estuaries are areas where sand, gravel, or shells. Most sand on the beach rivers and oceans meet and have a mix of comes from the breakdown of rocks, corals, saltwater and freshwater. Estuaries are home to seashells, and minerals. unique plant and animal communities that have The sandy shore ecosystem is always in motion adapted to brackish water—a mixture of fresh due to waves and wind. This makes it unstable water draining from the land and salty seawater. for many plants and animals. The organisms that inhabit the sandy shore all have special Oysters, crabs, and many birds like great herons adaptations to survive in this type of and egrets live in estuaries. environment. Many animals rely on estuaries for food, places Some organisms, like crabs, sea grasses, and to breed, and migration stopovers. snails, live there all the time. Other organisms, Coastal estuaries and their accompanying like birds and turtles, use sandy shores as wetlands are affected by tides and storms along feeding and nesting sites and are only there the oceanic coasts. some of the time.

Ocean Margin Habitats 1) Color and cut out the following Ocean Margin Habitat pictures. 2) Attach the picture as a flap over the correct information box. 3) Color and attach the following labels (or label by hand) to the pictures. 4) Trim and attach the information sheet to the correct page in your notebook. 5) Highlight the habitat names in the information boxes. 6) Highlight a border around the text boxes.