About the Pacific Shoreline Exhibit

The Intertidal Zone is the area of our planet where the land and sea meet. Exposed to sun, wind and predators during low tide and submerged by the ocean during high tide, only the hardiest and most well adapted creatures can survive and thrive here. Changing water levels, crashing waves and changes in salinity, or the "saltiness" of the water, are some of the challenges tidal organisms must adapt to and overcome. Despite these harsh conditions, Intertidal Zones have produced some of the most unique and diverse organisms and communities on Earth.

Inhabitants of the Intertidal Zone have developed an array of fascinating adaptations in order to thrive here. To keep from drying out at low tide and to protect themselves from both freezing and scorching temperature extremes, snails have adapted a survival tactic where they draw into their shells and essentially “shut the door” to the outside world. Anemones also do something similar where they draw their “arms” into their bodies and stick shells and rocks to their bodies to conserve moisture. Even sea slugs have learned hide under rocks or moist seaweed while they wait for high tide to return.

Crashing waves also pose a huge threat in the Intertidal Zone. To stay protected and avoid damage, being dislodged or even carried out to sea, creatures like limpets adhere themselves to rocks with a strong muscular foot, sea stars hold tight to rocks with multiple suction cup-like tube feet, and seaweed anchor themselves with strong holdfasts (roots).

During low tide, inhabitants in this area are left exposed to predators. Animals like the sea urchin have developed rigid spines to ward off any danger, sculpins change color to camouflage into their surroundings, and shore crabs hide in crevasses and under rocks.

The intertidal Zone is divided into four distinct sub-zones based on the amount of time each zone spends submerged or exposed: The spray zone, the high tidal zone, the mid tidal zone, and the low tidal zone. Each zone is inhabited by a characteristic group of organisms.

The spray zone is almost never fully submerged. Organisms here must either be able to move from this zone for moisture or must be adapted to retain moisture and withstand temperature extremes. Periwinkle snails and acorn barnacles are two organisms characteristic of the spray zone.

The high tidal zone is exposed to air for long periods twice a day. Organisms that live here must be able to tolerate long dry periods as well as strong ocean waves. Limpets and chitons call the high tidal zone home.

The mid tidal zone is exposed to air only for a brief period of time twice a day. This zone is more densely inhabited by a variety of animals. Sea stars and mussels can be found in the mid-tidal zone.

The low tidal zone is only exposed during the lowest tides and organisms here can be less adapted to the extremes that are common in the higher tidal zones. The low-tidal zone is often characterized by large brown algae communities, but is home to many difference species of fish and invertebrates.