Tide Pools and the Life Within Them main content.

Tide Pools and the Life Within Them

Part of Hall of Ocean Life.

by Talia, Grade 7, California - 2001 YNA Winner

I have lived by the ocean all my life and I was always very interested in the creatures that live by the seashore. My favorite beach is Doheny State Beach and I go there every summer. I always go at low tide and wade through the tide pools to find creatures. Twice a day the tide retreats and leaves all kinds of interesting creatures clinging to rocks or trapped in pools of water that collect around and between rocks. These pools are called tide pools. Tide pool animals are very well adapted to their ever-changing world of sand and surf. Almost every day of the summer I go to Doheny and search the tide pools for crabs, hermit crabs, limpets, snails, periwinkles, mussels, sea stars, chitons, sea urchins, and what I like to call sea slugs. By carefully turning over a few rocks and looking in shells I find these incredibly interesting creatures.

Tide-Pools-and-the-Life-Within-Them
Life forms within a tide pool (Click to enlarge.)

Doheny State Beach has a visitor center at the front of the park. The first thing I do on my expedition is go there. Inside, there is an indoor tide pool with many creatures such as sand sharks, sea stars, anemones, sea urchins, and a wide variety of fish. Salt water circulates through the tide pool to give the effect of waves and also to move small bits of food around the tide pool. There are also a few books in the visitor center that give some basic information about tide pools. I pick up a booklet that makes it easy for me to know what time high tide and low tide occur. All I have to do is look up the date and the high and low tide times for that day are listed. Now I know when to come and observe the tide pools.

I want to know about the creatures and the area they live in more thoroughly so I go to my local library, Aliso Viejo Branch Library. The library is a great place to go to find books about how tide pools form and the names and activities of the animals in tide pools.

 

September 14, 2000
It is 12:28 pm and the beach is deserted because of the cold weather. Doheny State Beach is closed because of the bacteria levels in the water. The first thing I see when I walk out onto the beach is rocks. When I look closer I see colonies of hermit crabs, snails, periwinkles, and mussels.

Hermit crabs have shells that serve as their houses. They have a hard covering called an exoskeleton on their front, and the rest of their bodies would be unprotected if they didn't have a shell. Hermit crabs live in abandoned snail shells. As they grow, hermit crabs move out of their small shells and into bigger ones. Hermit crabs are not the only shelled animals I see, though. Snails also live in shells.

Snails are a type of mollusk. Mollusks are a group of soft-bodied creatures that are usually protected by shells. Snails have tentacles on their heads and have one "foot" for walking and digging. They can pull in their "foot" and close the opening in their shells with a disc called an operculum. Snails are scavengers and grazers. They have sharp teeth on their tongues that shred food. Some snails can drill through the shells of other mollusks.Periwinkles are another group of animals I see on the rocks.

Periwinkles are a smaller species of snail. Rough periwinkles spend so much time out of the water and on the rocks that their gills take oxygen from the air.

talia_smallanimals_medium
From left to right: A hermit crab emerging from its shell; Sea urchin; Striped shore crab; Sea anemone

Another animal I see is attached to the rocks. Mussels are a type of bivalve mollusk. Bivalve mollusks have two shell sheld together by a hinge. These creatures spin strong threads from their feet that "glue" them to rocks or other mussels. Once a mussel is attached to a rock, it stays there forever. When it is high tide, mussels open their shells and filter out tiny plants and animals from the seawater to eat. When it is low tide, mussels close up and wait until high tide. It is getting late and the tide is starting to come in and the tide pools are disappearing. I plan to comeback next week and observe different creatures.