General Characteristics

Steep coasts without large amounts of sediment

West coast of US
– Active margin
– Uplift

Northeast Coast of US & Canada
– Ice sheets scraped sediment from the shelf

Conditions

Plenty of food
– Shallow water = lots of light
– Nutrients

Detritus
– Brought in by waves & tides
– Most important food source in many communities

Organisms in Rocky Intertidal

Mainly epifauna

Adaptations for attachment:
– Byssal threads
– Holdfasts
– Tube feet
– Cement

Barnacles

Periwinkles

Sea Star

Sea Anemones Lobsters
Sea Urchin Mussels

Palm Seaweed

Rocky Coast Communities

West coast of US has more mature communities
– Less seasonal changes
– Main limiting factor is predation

East coast is less mature
– Seasonal population changes
– Main limiting factor is climate

Competition for Space

Sessile organisms need place to attach

Space is limited

Ways to outcompete other species
– Large # larva
– Loosen competition from rock
– Grow over competitors

Ecological Succession

Vertical Zonation

In rocky intertidal, species not found throughout; rather in a particular range

Distinct bands of organisms at characteristic height in intertidal

Upper limit usu. determined by physical factors

Lower limit determined by biological factors – predation, competition

Keystone Predator

STARFISH FEEDING ON MUSSEL BED