The seashore is an inhospitable place for marine animals to live. Seawater has much less temperature variation throughout the year than air. In other words, during the summer in New York it can be 98˚F but the sea isn’t much warmer than 75˚F. In the depths of winter it can be –10˚F on land, but the water will be 48˚F. Animals that spend all their lives out at sea have a fairly steady environment. Those that are exposed to air at low tide, may face broiling hot temperatures in summer and freezing cold temperatures in winter. They may be soaked in fresh water when it pours with rain, and pounded by rough waves during a storm. Animals that can survive on the shore have to be tough! The higher the animals live up the shore the longer they are likely to be exposed to the land environmental conditions. On rocky shores this leads to bands of animals that are the best adapted to being exposed for that period of time. These bands are called tidal zones.
