Intertidal Zone

Intertidal Zones

Open Ended

What animals do you see at the beach?

Oceans have different zones according to their distance from land.

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Oceans and Tides

The intertidal zone is where the ocean meets the land.

Also called littoral zones, they experience both high and low tide

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Intertidal Zones

High waves splash constantly in this area. Only a few organisms like lichen, seashells, and rock lice live here.

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​1) Spray/Splash Zone

This zone is only underwater during high tide or storms.

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2) Upper Intertidal Zone

Animals and plants that live here are used to strong waves. There are barnacles, algae, seashells, hermit crabs, and crabs.

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2) Upper Intertidal Zone

This area is mostly covered in water during low tide or high tide.

Sea anemones, starfish, barnacles, crabs and mussels

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3) Middle Intertidal Zone

This area is almost always submerged. This zone has the most diversity in organisms like kelp, sea urchins, shellfish, crustaceans, starfish, red algae.

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4) Lower Intertidal Zone

Multiple Choice

This division experiences ocean splash from high waves.

• spray zone

• upper intertidal zone

• middle intertidal zone

• lower intertidal zone

Multiple Choice

This division is submerged only in high tides or storms.

• spray zone

• upper intertidal zone

• middle intertidal zone

• lower intertidal zone

Multiple Choice

This division has the most diversity of organisms.

• spray zone

• upper intertidal zone

• middle intertidal zone

• lower intertidal zone

The different habitats affect the survival of organisms who live there.

There are coral reefs, salty marshes, mudflats, and rocky shores.

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​Different Habitats of Intertidal Zones

They serve as shelter for fish and other organisms. Plankton and many fishes feed on coral.

Coral reefs protect the land from strong waves. They are rich, biodiverse habitats.

​1) Coral Reefs

Salt marshes are full of saltwater during high tide. They protect the shore from erosion.

They absorb rainwater to avoid flooding.

They filter the water to keep it clean.

​2) Salt Marshes

The earth in mudflats are deposited by rivers and seas through waves.

There are many migratory birds, crabs, fish, and mollusks.

They are great bird-watching spots.

​3) Mudflats

They are between high and low tide areas, and are made of solid rock.

Some organisms are adapted to the heat due to the rocks being exposed to the sun. However, there are areas submerged in water too.

​4) Rocky Shores

Multiple Choice

Which habitat is extremely biodiverse, and serve as shelter for many fish?

• coral reef

• salt marshes

• mudflats

• rocky shore

Multiple Choice

Which habitat is attractive to migratory birds, and are great bird-watching spots?

• coral reef

• salt marshes

• mudflats

• rocky shore

Living things in intertidal zones interact with each other.

The following slides show the distinct relationships between the organisms in intertidal zones.

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Interactions between Organisms

A predator is an animal that captures and eats other organisms.

The eaten animals serve as prey.

Zooplankton are eaten by plankton, which are eaten by larger animals.

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1) Predation

A parasite lives on or inside a host animal. The parasite lives off the host while causing damage to it.

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2) Parasitism

Mutualism is a kind of partnership where two animals help each other.

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3) Mutualism

Commensalism is a kind of partnership where only one organism is helped but the other is unbothered

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4) Commensalism

Multiple Choice

During high tide, sharks can swim freely around coral reefs. Some angelfish hide inside the corals during this time. What is the relationship between coral and angelfish?

• predation

• parasitism

• mutualism

• commensalism

Moisture - areas in these zones become submerged or dry at different times.

Waves - Organisms need to develop protection from powerful waves.

Salinity - some organisms can survive only at a certain level of saltiness.

Temperature - the tides cause the heat and cold to vary.

Sunlight - depth and presence of algae affect the amount of sunlight.

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Challenges in Intertidal Zones