What Helps Animals Survive in the Intertidal Zone?

Physical Stress

• Animals living in the intertidal zone are subject to physical stress due to the constantly changing water levels, currents and substrate (such as sand and rocks). Animals are at risk of drying out, being tossed in rough waves or being carried off by strong currents. Animals adapt special behaviors to help them avoid or survive these stresses. Barnacles and seaweed attach to immovable objects. Clams have developed a protective shell and burrow under the substrate. Crabs and fish hide beneath vegetation and rocks or move into deeper water as the tide subsides.

Accessing Food

• Food and sunlight are a challenge to obtain in the intertidal zone. Various hunting strategies have been developed to ensure species survival. Seaweed will cling to an immovable object to access sunlight in the upper levels of the intertidal zone. Some species like snails and worms will take up residence with their food source, keeping it conveniently accessible. Fish and other species will move about in search of food or remain motionless to ambush bypassing prey. Anemones stick to one place and filter passing water for food, and phytoplankton breed rapidly and travel with the current.

Avoiding Predation

• Being eaten by other animals is a real and constant threat to species dwelling in the intertidal zone. Behavioral techniques such as hiding and escaping have been adopted by species of fish, clams, crabs and shrimp. Species such as sea urchins and anemones have developed special weapons like sharp spines and stinging chemicals to ward off predators. Tough shells act as a suit of armor for barnacles and clams, making it difficult for teeth to penetrate into vital organs.

Tide Pools

• Tide pools present specific challenges for marine life. Any organisms living in a tide pool have to be adapted to the significant changes in water temperature that accompany the change in season. They must be able to cope with changing levels of salinity and changes in water level. Animals that have developed these abilities include shrimp, shore crabs, sea anemones and small species of fish.