Marine Biology - UNIT 9: Intertidal Zone

Intertidal zone

The area between the highest tide and the lowest tide

“where the land meets the sea”

Rocky shore community

-exposed to air

-known as the littoral zone because of all the littoral snails

-common on the west coast

-hard rocky bottom

-Geologically young

-temp and salinity fluctuate greatly

-consists of epifaunal organisms (some move, some don’t)

upper intertidal

-wet only during the highest Spring high tides --mostly dry

-spray/mist zone

-barnacles and limpets are common

Middle intertidal

-wet and dry everyday

-splash/crash zone

-ecological succession is very prominent here because of crashing waves

-seastars, chitons, mussels, and sea anemones are common

lower intertidal

-dry only during the lowest Spring low tides

-mostly wet

-wet/water zone

-octopus, red abalone, sponges, seaweeds, and seagrasses are common

Competitive Exclusion Principle

two species can't coexist if they occupy exactly the same niche

-ex seastars

wave shock

due to increased hydraulic pressure from energy generated by crashing waves

adaptations: migration, anchors, glue, byssal threads, suction, thick shell, low profile, flexibility, absence of swim bladders

abrasion

due to materials suspended in the water

adaptations: shells and hiding

increased predation

fish and marine mammals

adaptations: closing down, hiding and migration

decreased temperature

adaptations: dark color or light color (depending on zone)

desiccation (drying out)

adaptations: closing down, hiding in moist crevices, suction to trap moisture, staying in a tidepool

UV radiation

adaptations: cover with shell bits, closing down and hiding

salinity

rain dilutes tidepools and excessive heat evaporates water from tidepools

adaptations: migration or just bearing with it

Sessile feeding

suspension or deposit feeding

mobile feeding

grazing, predation, or deposit feeding

Soft bottom community