1. ROCKY INTERTIDAL ZONE
Western US rocky intertidal zones –less seasonal changes.
The greatest limiting factor is space.
Eastern US soft-bottomed intertidal zones - temperature changes cause seasonal population changes.
The greatest limiting factor is climate.

2. Rocky coasts are characterized by:
- abundant food supply with good light
- tides produce hours of flooding in cool water followed by desiccation (drying out) and high temperatures
- tidal pools are created and emptied
- temperature and salinity fluctuate
- very distinct zonation worldwide
- wave shock
- competition for space fierce (limiting factor)

3. COPING STRATEGIES / ADAPTATIONS:
WATER LOSS:
run & hide, clam up, tolerate
allow drying out
find tide pools
TEMPERATURE
tolerate
move to moist areas
light color
SALINITY
clam up
tolerate
RESTRICTED FEEDING (MOST ARE FILTER FEEDERS)
only feed when tide is high
tide height determines where they can live

4. COPING STRATEGIES / ADAPTATIONS:
WAVE SHOCK:
attach (holdfasts, byssal threads, glue)
cling (suction cups)
fish lack swim bladders
find shelter
thicker shells
compact shape
low profile
go with the flow / flexible

5. Wave action cuts rocks into sea caves, cliffs and sea stacks that provide shelter. Competition for these limited living spaces is high.
Inhabitants must find a place to attach or hide or be crushed between waves and rocks.
Methods of attachment include cement, byssal threads, holdfasts, muscular and tube feet, and boring.

6. Adaptations also include symbiosis and reproductive strategies, like hermaphrodites and organisms that change sex.
NOAA
The rocky coastal communities’ succession has a predictable pattern that is often controlled by sea urchins. Grazing urchins remove algae from rocks.

7. New communities can then begin because one group doesn’t over populate the area.
Pioneer stage - bacteria and algae
Juvenile - protozoa and worms
Mature - barnacles, rockweed,
mussels, seastars and sea urchins
Collectively these animals became known as fouling communities because of their harmful effects on ship’s hulls, docks, pilings, and the smell they create at low tide.

8. THE BATTLE FOR SPACE
AVAILIBILITY OF SPACE LIMITS
POPULATIONS IN INTERTIDAL
COMPETITION FOR SPACE
DOMINANT BIOLOGICAL FACTOR
HOW TO COMPETE
- be first to get to open space
- effective dispersal
- reproduce rapidly
- take over
- grow over

9. VERTICAL ZONATION
UPPER, MIDDLE & LOWER ZONES
UPPER LIMIT SET BY PHYSICAL FACTORS
LOWER LIMIT SET BY BIOLOGICAL FACTORS (predation & competition)

10. Sea Star Predators
Sea Stars Dying

11. Sea Star Dissection