Download Sandy Ecosystems and Organisms

Sandy Ecosystems and Organisms
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.