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Communities on Rocky ShoresEpifauna

Attached to substrate (e.g., marine algae)

Move over seafloor (e.g., crabs, snails)

Moderate diversity of speciesGreatest animal diversity at

tropical latitudesGreatest algae diversity at mid-

latitudes

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I. Intertidal Zonation (Spray Zone & Tidal Zones)Rocky shore:

Spray zone – above spring tide zone

Intertidal zone High tide zoneMiddle tide zoneLow tide zone

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a) Spray Zone Supratidal zone

Organisms

Avoid drying out

Many animals have shells

Few species of marine algae

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b) Intertidal Zone Organisms (Tidal Zones)

1. High tide zoneAnimals have shells to

avoid drying outMarine algae—rock

weeds with thick cell walls

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Intertidal Zone Organisms2. Middle tide zone

More types of marine algae

Soft-bodied animals (Barnacles)

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Intertidal Zone Organisms3. Low tide zone

Abundant algaeMany animals

hidden by sea weed and sea grass

Crabs abundant in all intertidal zones

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2. Sandy Beach Organisms and Adaptations

Burrowing animals

No stable, fixed surface

Burrowing provides more stable environmentLess risk of

temperature extremes and drying out

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Sandy Beach Organisms and Adaptations

Bivalve mollusksSoft body, hard shellExample: clams

and musselsGreatest number in

low tide regions

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Sandy Beach Organisms and Adaptations

CrustaceansSegmented body,

hard exoskeleton, paired jointed limbs

Example: crabs, lobsters

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Sandy Beach Organisms and Adaptations

EchinodermsSpiny skinFive tapered

legsExample:

starfish and heart urchin

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3. Mud FlatsEelgrass and turtle

grass common

Bivalves and other mollusks

Fiddler crabs

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4. Shallow Offshore Ocean Floor Communities

Rocky bottoms (subtidal)

Kelp and kelp forests Attaches to rocky

bottoms Can grow up to 0.6

meters (2 feet) per day

Productive ecosystems

Provides shelter for other organisms

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Kelp Distribution

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5. Rocky Bottom Shallow Offshore Ocean Floor Communities

LobstersLarge, spiny

antennaeLive in water deeper

than 20 meters (65 feet)

ScavengersAlso feed on live

animals

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Rocky Bottom Shallow Offshore Ocean Floor Communities

OystersSessile bivalve

mollusksThick shellStart life as

plankton