Rocky Beach


The vertical face of the rocky beach, as seen in the photograph, is divided into several areas or layers.  The upper area is covered by upland plants.  This area is rarely, if ever, covered by salt water so no salt water species grow there (however some may be salt tolerant).  Below that is a bare area that is thin or wide depending on the exposure to the sun, amount of freshwater runoff, and exposure to salt spray.  Further down is black material that looks like oil.  In fact it is a lichen called Verrucaria which marks the upper zone of salt water tolerant animals and plants.  Small hardy marine snails called Periwinkles also frequent the area.  Just below this black layer is a thin, white layer of Barnacles.  Continuing downward lies the first of the true marine plants, the brown seaweed called Rockweed or Fucus.  Often found among the rockweed are several species of snails called Limpets with shells that look like little hats.  The next lower layer is a black mat of the Edible or Bay Mussel which shelters a variety of small animals.  The lowest layer is a wide zone of several species of brown, green and red marine algae such as Sugar Kelp, Crustose Coralline Algae and Sea lettuce.

When the tide comes in, the intertidal world changes.  Not only is there fresh sea water for breathing, flushing away waste products, bringing in nutrients, and protection from the heat or cold, but it also brings in the predators or allows the ones who stayed to come out of hiding.   For example the Purple Sea Star moves up to feed on the mussels and barnacles.  Several species of marine fish such as the Tidepool Sculpins and  Clingfish  move among the seaweed feeding on small crustaceans.  The limpets and periwinkles arise from their low tide slumber to begin feeding on algae. TIDE POOLS which served as a refuge at low tide now join to open water so the oxygen and nutrients can be refreshed.  Found under rock shelves or large boulders are  Rock Pricklebacks, Tube Sponges and the Northern Feather Duster Worm

Subtidal rocky sites in protected as well as high current areas have many more species.  Since they require diving to view they are not covered here.  However many of the animals and plants that naturally occur on subtidal rocky sites also can be found under floats and on piling at local marinas.

Other organisms found associated with rocky areas, including those with boulders and large cobble are:  Rainbow-leaf Seaweed, Sea Brush, Sea Cauliflower, Bleach Weed, Five-ribbed Kelp, Polysiphonia, Painted Anemone, Aggregating Anemone, Polyclad Flatworm, Slime Worm, Red-flecked Mopalia, Frilled Dogwinkle, Japanese Oyster Borer,Rock Oyster, Opalescent Nudibranch, Shaggy Mouse Nudibranch, Thickclaw Porcelain Crab, Purple Shore crab (Hemigrapsus nudis), Pigmy Rock Crab, Puget Dwarf Brittle Star, Mottled Sea Star, Orange Sea Cucumber, White Sea Cucumber, Mushroom Sea SquirtSlimy Snailfish, Great Blue Heron, River Otter and Harbor Seal.   In the sediment around cobbles can be found the Littleneck clam, Manila clam and Butter clam.