Tide pool

A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. These pools typically range from a few inches to a few feet deep and a few feet across.^[1] Many of these pools exist as separate bodies of water only at low tide, as seawater gets trapped when the tide recedes. Tides are caused by the gravitational pull of the sun and moon. A tidal cycle is usually about 25 hours and consists of two high tides and two low tides.^[2]

Tide pool habitats are home to especially adaptable animals, like snails, barnacles, mussels, anemones, urchins, sea stars, crustaceans, seaweed, and small fish.^[1] Inhabitants must be able to cope with constantly changing water levels, water temperatures, salinity, and oxygen content.^[2] At low tide, there is the risk of predators like seabirds. These pools have engaged the attention of naturalists and marine biologists, as well as philosophical essayists: John Steinbeck wrote in The Log from the Sea of Cortez, "It is advisable to look from the tide pool to the stars and then back to the tide pool."^[2]

Some examples have been artificially augmented to enable safer swimming (for example without waves or without sharks) in seawater at certain states of the tide.^[3]