Major habitats of puget sound


Intertidal zone and associated Habitats

Did you know that Puget Sound has a ring around it just like a bath tub?  The ring is easy to see on rocky shores like the one shown in the photograph.  The ring is not caused by pollution, but rather by animals and plants growing below the high water mark.

Intertidal Zone means "between the tide lines" or the vertical dimension of a beach that is exposed when the tide recedes.  In Puget Sound the tide moves in and out two times every 24 hours. The inhabitants are subjected to wide extremes of temperature and salinity and are a hardy breed.  See discussion of Tides and Intertidal Zonation.

The habitats in the intertidal zone are varied and complex.  They are categorized by the type of substrate: rock, cobble/gravel, sand or mud; the degree of exposure to drying (intertidal vs subtidal), energy (strong or weak currents or waves) and level of salinity.

Hard rock can serve as an anchor for a variety of plants and animals leading to a striking two dimensional visual display of living zones.  On the other hand, the soft substrate of mud, sand, gravel or some combination thereof doesn't allow for the surface attachment of many creatures due to it's instability.  But soft substrates offer a bonus by allowing animals to burrow under the surface for protection and food.   This three dimensional world can offer a home to many kinds of animals as well as the occasional plant.

Tide pools are scarce in southern Puget Sound becoming common in more rocky areas.

The major intertidal habitats are: Rocky Beach, Sandy Beach, Sandy Mud Beach  and Piling and Floating Dock.   (See map of south Puget Sound intertidal habitats)  Piling and Floating Dock are unusual in that piling is like a vertical rocky intertidal zone while the floating dock is like a rocky subtidal zone in that it usually is constantly underwater with a hard surface. 


A wide variety of animals and plants live full or part time, floating or swimming in the open water.  This is because of the physical properties of water: it supports organisms, provides nearly constant temperatures and  reduces salinity variation.  Many species spend their baby and juvenile time in the open water feeding on the abundant plankton before they settle to the bottom as adults. Go to Open Water Habitat page.

Intertidal Zone Survival Techniques

Animals and Plants use a variety of techniques that allow them to live in the intertidal zone.  Explore these techniques on the Survival Techniques page.

Who eats Who?

The residents of each habitat interact in a variety of ways.  One major way is through the food web.  A food web is an interlinked  system of energy flow where animals who eat seaweed or plankton produced from sunshine are eaten by others. 

An illustration of a detailed food web for a sandy mud habitat can be found here

View the video from for another view of a food web.

Brief history of pacific coast marine ecology is here.