The Rocky Seashore

Life in a Tide Pool

MARE/Rocky Seashore/Seashore Charades/University of California©2002

Ocean Waves

Organisms that live at the rocky seashore must be able to survive the crash of as many as 8,000 waves every day. These waves bring water full of oxygen and food to animals that live there. This is a very good thing.

What might be bad about crashing waves?’

How might it feel to be hit by a crashing wave?

How do you think animals and seaweeds protect themselves from waves?

Organism Adaptations

To survive waves, organisms need adaptations such as:

Hold tight to the rocks

Hide in cracks and crevices

Have a hard shell for protection

Have a rubbery body to bend and sway in the waves

Fly or run away to keep from getting swept out to sea

High and Low Tides

All the time the waves are crashing on the edge of the rocky seashore, the water of the ocean is slowly rising up towards the cliffs or slowly moving back toward the shore. This slow movement of water is called the tides.

The time it takes for for water to go from low tide to high tide is about 6 hours.

High Tide

When the tide is high, the water covers most of the seaweeds and animals.

The sun can’t dry them out and birds can’t eat them.

The waves bring food and oxygen rich water.

Low Tide

When it is low, the seaweeds and animals are uncovered.

The organisms must protect themselves from drying out and predators.

Even though the tide is out, some seaweeds and animals are still covered safely with water. They are living in a tide pool.

Sculpin

This tide pool fish is called a sculpin. What adaptations do you think this sculpin has that help it live at the rocky seashore?

Acorn Barnacles

What adaptations does this barnacle have?

Barnacles start out their lives as plankton. Plankton are organisms that are very weak swimmers and are pushed this way and that by the wind and moving water.

The tiny barnacles drift through the water riding on the waves and moving water looking for a good place to live. When they’ve found the right spot on a rock or the shell of another animal, they cement themselves onto their new home.

They build volcano-shaped shells around their bodies to protect themselves from predators and the drying effects of the sun.

Purple Shore Crab

What adaptations do you see here?

This shore crab has a hard outer shell called an exoskeleton. Crabs have eight walking legs and two pincers, which they use to protect themselves. These animals can remain out of water for quite a while, but must keep their gills wet so that they can breathe.

Hermit Crab

What adaptations does this hermit crab have?

Unlike shore crabs, hermit crabs are only partly protected by a hard exoskeleton. Their walking legs, claws and head have protective armor, but their stomach and abdomen are soft and vulnerable so they need to find a shell to wear for protection.

Giant Green Sea Anemone

What adaptations do you see here?

This giant green sea anemone is an animal that looks very much like a flowering plant. Anemones live attached to a rock and have tentacles that sting their prey when the prey comes too close. The tentacles then pull the food into their mouths.

Bat Star

What adaptations do you see here?

The colorful bat star, a type of sea star, is holding on tight to keep from being washed away by the waves.

Ochre Sea Star

What adaptations do you see here?

Most sea stars, like this ochre star, have five arms or rays, and suction-cup-like tube feet for holding on tight, moving around and capturing food.

Though they live in the low zone, nearest to the water, they eat mainly mussels from the mid-zone. At high tide, sea stars travel up to the mussel beds to feed and then follow the tide back down to the low zone.

Western Gull

What adaptations do birds have?

Sea Palm

Here is a seaweed called a sea palm. What adaptations do you see here?

The sea palm grows only in the low zone where the waves are the strongest.

Octopus

What adaptations does an octopus have to survive in the tide pools?

Octopuses don’t have a hard shell to protect them so these intelligent animals use camouflage as one way to protect themselves from predators. An octopus usually lives in a hole or cave within the rocks.

Lined Chiton

What adaptations do you see here?

Chiton have one large muscular foot like the snails they are related to. They use their foot to attach very tightly to a rock.

Chitons have a shell made up of eight overlapping butterfly-shaped parts. When they are pulled off a rock, they can roll up to protect their soft foot.

California Mussels

What adaptations do you see here?

Mussels have two shells like a clam. Mussels don’t have a foot adapted for hanging on like a chiton or for digging in sand or mud like a clam. Instead mussels use their foot to attach threads from their body to a rock with one of the strongest glues in the world. Mussels stay attached even in the strongest waves.