page_title: Rock pool
section_title: Tide pool zones, from shallow to deep
hierarchical_section_title: Rock pool / Tide pool zones, from shallow to deep
caption_attribution_description: Sea Star is in process of consuming a Mussel. Photograped by Brocken Inaglory in Northern California
context_page_description: Rock pools are rocky pools by the sea. They are in the intertidal zone. They are filled with seawater during high tide, and exist as separate pools at low tide.
  Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists.
context_section_description: The water  level is always changing. Twice a day, the tide rises up the shore and then goes back again . When the tide starts to go back out, the upper shore is left exposed until the next high tide, 12 hours later. The rocks around the rock pool are covered by seaweed . seaweeds are plants, but they do not have roots like garden plants.
  This zone receives spray from wave action during high tides and storms. At other times the rocks experience other extreme conditions, baking in the sun or exposed to cold winds. Few organisms can survive such harsh conditions. Lichens and barnacles live in this region. In this zone, different barnacle species live at very tightly constrained elevations. Tidal conditions precisely determine the exact height of an assemblage relative to sea level.
  Since the intertidal zone often desiccates when the tide is out, barnacles are well adapted to water loss. Their calcite shells are impermeable, and they possess two plates which they slide across their mouth opening when not feeding.  These plates also protect against predation.
caption: Starfish Pisaster ochraceus eating a mussel ouside a tide pool
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