Grades K–2 · Organisms
Why does a little pool stay when the sea pulls away?
When the sea moves back from a rocky shore, water can remain in hollows in the rock. These little bowls become tide pools. A rock edge holds the water, much as the edge of a bowl does, while the sea outside drops lower.
A pool gives small sea animals a wet place until the water rises again. An anemone may open its soft tentacles underwater. A small snail can move over the rock. Outside the pool, exposed animals need other ways to keep from drying out.
The upper picture shows a flooded shore; below, the rock rim holds a pool.
The pool is not exactly like the open sea. Sunshine can warm its water, and some water can evaporate. Later, a rising tide brings seawater over the rock again. A tiny hollow can change which animals are able to live on a shore.
About this explanation
This picture shows one rocky hollow; the height and timing of tides vary from place to place.
Starting knowledge: Recognize plants, animals and places where they live.
Sources
- National Park Service — Visit the Cabrillo Tidepools