The organisms that live in the intertidal zone, experience many stresses. When the tide recedes, the rocks offer little protection to the plants and animals that live on and around them. The upper limits of distribution of intertidal organisms are determined by physical factors such as drying, high temperatures, and solar radiation; and biological factors such as food availabilty. Lower limits are often set by biological factors such as, competition for space and predation. Here is a list of some of the biological, physical, and chemical stresses they endure:

Biotic Stresses   Abiotic Stresses Competition for space Competition for food Predation Food availability Grazing   Temperature extremes Dessication or drying out Wave action Salinity and freshwater input Pollution Freshwater runoff

Intertidal plants and animals are adapted to survive these stresses. These adaptations include attaching themselves to the rocks like barnacles or having a special shape to their shell, such as the smooth, rounded shell of the limpet. We'll discuss more of these adaptations as we meet the organisms and the zone where we can find them.

(click on the film for more images)