How do tides affect marine life?
The vertical movement of water once or twice a day has tremendous importance for intertidal biotic communities, those plants and animals that colonize the shoreline between the high and low tides. They must be able to withstand a number of stresses such as the force of waves, exposure to the air and changes in salinity. With exposure to the air they are at risk of desiccation (drying out), freezing, overheating or starvation, since most animals can only feed when submerged. Tides therefore create niches in the shoreline ecosystems that are available to different organisms, depending on their tolerance to these conditions. This leads to intertidal zonation, the tendency of plants and animals to form visible communities along the marine shoreline, between the high and low tide lines. Tide pools are depressions in rocks that are flooded regularly with sea water, but isolated at low tide. They provide rare opportunities to observe marine life that may normally live below the low tide line
