What typically limits the upper distribution (closest to land) of rocky intertidal organisms?
The upper limit at which a species occurs is usually determined mainly by physical factors, such as the ability to withstand desiccation. 33. Why typically limits the lower distribution (farthest from land) of rocky intertidal organisms? The lower limit at which a species occurs is usually determined mainly by biological factors, especially predation and competition. 34. Describe the upper intertidal zone with respect to physical conditions and typical types of organisms. The upper intertidal zone experiences frequent and prolonged exposure to air. In fact, much of the upper intertidal zone may lie above the high tide mark and may be wetted by wave splash. Typical organisms include lichens, encrusting algae, periwinkle snails, and sometimes limpet; all of which have strategies to avoid desiccation. 35. Describe predators in the upper intertidal zone. Few marine predators can reach the upper intertidal zone. Those that do include crabs and snails. More frequently, predators include land
