Tidal Pool

Tide Pool Challenges, Animals and Plants

A tide pool along the coast of southern California is home to starfish, mussels, sea anemones, and much more
A tide pool along the coast of southern California is home to starfish, mussels, sea anemones, and much more. magnetcreative/E+/Getty Images

A tidal pool, also commonly called a tide pool or rock pool, is water left behind when the ocean recedes at low tide. Tidal pools can be large or small, deep or shallow. 

Where Are Tide Pools?

You'll find tidal pools in the intertidal zone, where land and sea meet. These pools usually form where there are areas of hard rock, and parts of the rock have eroded away to form depressions in the rock. At high tide, ocean water collects in these depressions.

As the water recedes at low tide, the tide pool temporarily forms. 

What is in a Tide Pool?

There are many marine species found in tide pools, from plants to animals.

Animals

Although vertebrates such as fish occasionally inhabit a tide pool, the animal life is almost always composed of invertebrates.

Invertebrates found in tide pools include:

  • Gastropods such as perwinkles, whelks and nudibranchs
  • Bivalves such as mussels
  • Crustaceans such as barnacles, crabs and lobsters
  • Echinoderms such as sea stars and sea urchins.

Seabirds also frequent tide pools, where they wade or dive for prey. 

Plants

Tide pool plants and plant-like organisms are important for food and shelter in a tide pool. Coralline algae may be found encrusting over rocks and the shells of organism such as snails and crabs.  Sea palms and kelps may anchor themselves to bivalves or rocks.  Wracks, sea lettuce and Irish moss form a colorful display of algae.

Challenges of Living in a Tide Pool

Animals in a tide pool must deal with changing moisture, temperatures and water salinity. Most also can face rough waves and high winds. Thus, tide pool animals have many adaptations to help them survive in this challenging environment.

Adaptations of tide pool animals may include:

  • Shells - animals such as snails, barnacles and mussels have strong shells, crabs, lobsters and shrimp have hard exoskeletons. These structures protect these animals from predators and help keep their bodies moist in dry conditions.
  • Clinging to rocks or to each other - Sea urchins and sea stars cling to rocks or seaweeds with their tube feet. This keeps them from being washed away as the tide goes out.  Some animals, like barnacles and periwinkles cluster together, which provides greater protection from the elements.
  • Hiding or Camouflage - Sea urchins can camouflage themselves by attaching rocks or weeds to their spines. Crabs bury nearly their whole body in the sand. Many nudibranchs blend in well with their surroundings. Sometimes, octopuses are found in tide pools and they can change color to camouflage themselves.

Advantages of Living in a Tide Pool

Some animals live their entire lives in one tide pool, because tide pools are full of life.  Many of the animals are invertebrates, but there are also marine algae, which provide food and shelter, plankton in the water column, and fresh nutrients delivered regularly by the tides.  There are also plenty of opportunities for shelter for animals such as sea urchins, crabs and baby lobsters, who hide in seaweeds, under rocks, and burrow in sand and gravel.

Don't Remove Them From Their Home

Tide pool animals are hardy, but they won't survive for long in a beach pail or your bathtub. They need fresh oxygen and water, and many depend on tiny organisms in the water to feed upon.  So, when you visit a tide pool, quietly observe what you see. The quieter and calmer you are, the more likely you will be to see more marine life. You can pick up rocks and view the animals underneath, but always put the rocks back gently. If you pick the animals up, put them back where you found them. Many of these animals live in a small, very specific area.

Tide Pool Used in a Sentence

He explored the tidal pool and found sea urchins, starfish and crabs.

References and Further Information:

  • Coulombe, D.A. 1984. The Seaside Naturalist. Simon & Schuster: New York.
  • Denny, M.W. and S.D. Gaines. 2007. Encyclopedia of Tidepools and Rocky Shores. University of California Press: Berkeley.