Several kinds of sea birds nest on offshore rocks. Intertidal Zone Twice daily on a 25-hour lunar cycle, tides rise and fall. In the zone between high and low tide, life forms arrange themselves vertically. A splash zone just above high tide is home for periwinkle snails and beach hoppers that can withstand the powerful shock of pounding waves and episodic wetting. Splash zone inhabitants are transitional creatures, but they are more attuned to life on land than in the sea.
Mussels cling to rocks in the high-tide zone covered by water only at high tide.
Tidepools form in rocky beach outcroppings to shelter life forms found only in these environments. You can see more animal species here than in a single visit anywhere. Tidepool dwellers must cope with changes in water temperature, salinity, and oxygen content. Here are barnacles, limpets, sea urchins, sea stars, and sea palms. Beaches Life on sandy beaches also observes wet and dry zones based on tides and waves.