Life in the Tidal Zone
Survival!
What is an Estuary?
An estuary is a
semi-enclosed body
of water where
freshwater meeting
and mixes with
saltwater.
Tidal Zone Adaptation
Tidal habitats change daily with the tides,
so organisms adapt, or adjust to changing
environmental conditions with special features to:
Avoid drying out
Limpets shape their
shells to fit a specific
rock: effective seal
against water loss
Anchor themselves to resist waves
Tube feet of sea
star used for
locomotion and
suction/anchorage
Protect themselves from predators
Hermit crab
hiding in it’s
scavenged shell
Pipefish well
camouflaged in
eelgrass bed
Types of Tidal Habitats
Different tidal habitats require different adaptations
Sandy Beaches and Mud Flats
•
• Substrate offers lots of nutrients,
but little structure for attachment •
• Animals bury themselves in mud •
• Can also attach to plants
Rocky Shores
Little protection from strong waves:
animals must anchor
Complex tide pools possible
Seaweeds offer protection from
drying
Tidal Zones
Tidal habitats are divided into zones based on relative
beach location and how often they are covered by water
Splash Zone
Intertidal Zone
High, Mid and Low
High Tide Zone
Middle Tide Zone
Low Tide Zone
Zones
affected daily
by changing
tides
Adaptations
are required
to avoid
drying out,
wave action
and predators
Splash Zone
 High on beach
 Out of water most of the time
Species must tolerate salt, heat, cold, and
extended dry periods
 Adaptation example: Amphipods bury
themselves to stay moist when the tide is out.
Splash Zone Life
Lichen
Isopods
Blue-Green
Algae
Amphipods
Periwinkles
High Tide Zone
 Increased wave action
 Tide pools provide some protection
 Adaptations include ability to survive
exposure to air without drying out and to
survive wave action.
Adaptation example: Anemones survive
wave action by attaching themselves to the
sheltered side of large rocks
High Tide Zone Life
Limpets
Anemones
Barnacles
Shore Crab
Rockweed
Middle Tide Zone
 Most active region
 Covered and uncovered twice a day
 Life must tolerate BOTH submersion in water and
exposure to air
 Animals move in and out of adjacent zones to feed
 Adaptation example: The tube feet of a star fish
allow it to suction on to surfaces
Middle Tide Zone Life
Wrinkled Whelks
Pisaster Sea
Stars
Anemones
Japanese
Eelgrass
Batillaria snail
Low Tide Zone
 Most food and shelter
 Less exposure to air and heat – under
water for a lot of the time
 Animals unable to exist in other zones
because they will dry out
 Adaptation example: Tube worms build hard
tubes around their soft bodies for protection
Low Tide Zone Life
Black Katy Chiton
Tube Worm
Opalescent
Nudibranch
(sea slug)
Orange Sea Cucumber
Native Eelgrass
Summary
Splash Zone
Exposure to Water
High Tide Zone
Middle Tide Zone
Low Tide Zone
Most time
Each zone requires unique
adaptations for survival