Other Issues in the Strait

Marine Habitat: The Intertidal Zone

The intertidal zone is the part of the beach that’s covered by water at high tide and exposed at low tide.

The intertidal zone is regularly exposed to the air, wind, sun, rain, and sea water as the tide moves in and out, so animals and plants that live in the intertidal zone have to adapt to an ever-changing environment.

Despite this challenge, the intertidal zone is full of life. It provides a home to many different kinds of species, acts as a nursery for numerous subtidal (deeper water) species and is an important indicator of the overall health of the marine environment.

Sun star. Photo by Judith BurkeSea stars are well suited for the changing environment in the intertidal zone, with their tough, leathery surfaces that keep them from drying out when they're exposed to the air at low tide.

GSA file photo

Other intertidal animals cope with the tide changes differently.

Crabs move up and down with the tide.

Black Oystercatcher. Photo by Jim DemlerOne of the birds that lives in the intertidal zone is the Black Oystercatcher. Despite its name, its usual dinner is limpets and mussels, which it whacks off the rocks and pries open with its bill.

Eelgrass. Photo by Laurie MacBrideEelgrass grows up to 4 feet long, in large meadow-like beds. It’s found in protected bays, especially along the east coast of Vancouver Island and the Fraser delta. Eelgrass beds provide habitat for fish and invertebrates, and its roots help stabilize mud or sand bottoms.

Great blue heron. Photo by Judith Burke.Eelgrass meadows are essential for a number of birds, including the great blue heron. Herons wade in the shallows and catch small fish and crabs by stabbing them with their narrow bills.

Learn more: