Barnacles are often exposed to the air for a few hours during low tide. They close their shells tightly until the water rises again. Barnacles are filter feeders, they extend 5 "fingers" which they wave in the water to catch small animals. Note the small barnacles growing on the mussel shells, no space is wasted in a tide pool!
and barnacles on a large Cockle shell
We were delighted to come upon this wonderful tide pool when we went to the beach in Malibu. We found hermit crabs, sea anemones, and I found this huge sea urchin. When I got back to school in TN the following week, I was telling some of the teachers about my trip. When I mentioned that we went to Malibu, one of the teachers excitedly asked if I saw any of the movie stars homes. I answered, "Uh, no, we went to a tide pool!" She said, "Kris, you do exactly what I would NOT do on my vacation!" :) I'll take a good tide pool over a movie star's home any time!