In which oceanic zone do clams and crabs survive by burrowing in the sand?

• A. oceanic
• B. open ocean
• C. intertidal
• D. deep ocean

Answer: (C)

The important idea here is understanding coastal habitat zones and how organisms adapt to them. Clams and crabs that burrow in sand are using the beach area where land and sea meet—the intertidal zone. This zone sits between the high-tide line and the low-tide line along coastlines. Burrowing helps these animals stay moist during low tide, avoid desiccation, and hide from predators and waves when the tide is out. When the tide comes in, they can feed and move with the water.

The other zones are more for open-water living. The oceanic or open-ocean and deep-ocean zones are far from shore and lack the sandy, tide-regular environment that makes burrowing in beach sand advantageous. So the intertidal zone is the place where clams and crabs commonly survive by burrowing in the sand.