Characteristics of a beach ecosystem:
The sandy beach environment has lower diversity than other environments since the sand holds less organic matter, food and nutrients. The organisms that call it home must have either physical or behavioral adaptations to help them survive in the harsh environment. They must deal with pounding surf, abrasive sand, periods of wetness and dryness, temperature changes and exposure to the sun. Another major factor organisms must overcome is that on a sandy beach there are no sold objects for the animals to hold on to and avoid being washed by the waves or the tides. Most sand beach animals escape these physical factors of the environment by burrowing. Much of the community lives underground and move up and down the beach with the tide.
The beach can be divided into vertical zones, each having different physical characteristics and organisms that live there.
A.
Dunes - the dunes are important nesting grounds for shorebirds, terns and gulls. In the zone of the dunes to the high tide level, there are many dune plants, such as the silvery beach croton, waving sea oats, railroad vine, sea purslane, and yellow beach evening primrose. Animals in the area include rattlesnakes, lizards, ground squirrels, kangaroo rats, mice, insects, gophers, and other small rodents.
B.
Supralittoral zone – this zone begins at the base of the dunes to the high tide line. No plants are found in this area. Ghost crabs and tiger beetles are the most obvious animals in this area. Sea turtles also use these areas for nesting sites (they usually build them at the base of the first row of dunes)
C.
Surf zone – this zone contains the area on the beach that is pounded by the surf during high tide, but during low tide, is exposed to the air and sun. There are no plants in this zone. This habitat is home to many invertebrates that burrow into the bottom because the excellent water circulation in the surf brings in large quantities of marine phytoplankton. These microscopic plants support large populations of burrowing marine invertebrates. At high tide, some burrowing clams dig out to feed. Others poke tubes above the sand surface to pull in water that contains their food. The burrowing animals construct different types of burrows and live at different depths. Marine organisms can only use materials found on the beach and secretions they produce to make their burrows. The marine invertebrates are so abundant that they directly or indirectly feed surf fishes and shorebirds. This area is inhabited by the bean clam (coquina), mole crab, lettered olive an moon snail, hermit crabs, auger shell and tube building worms. Shorebirds that feed here have beaks that are adapted to catch the burrowing organisms where they are hiding.
D.
Sublittoral zone – this zone is located below the tide level, and is always covered by water. Common organisms include the sand dollar, scotch bonnet, starfish, sea star, sea pansy, and sea whips. Crabs, shrimp, clams, octopus, and certain species of fish are also common. Fish eating birds, such as gulls, terns, cormorants, ospreys, and pelicans are found here as well.