Seaside

Shorelines of oceans, seas, and large bodies of water around the world are habitats for plants and animals that thrive in challenging conditions.  Tides occur twice each day when water levels rise over a six hour period to cover large areas before receding to leave those same areas open to the air until the next tide starts to move inland again.

^{Nearshore habitat zones by King County, WA; Littoral Zones by US Government}

Shoreline habitat has been classified into zones often known by many different names.  The intertidal zone is the area affected by changing temperature and salinity conditions as water moves in and out with each tide.  The subtidal zone is the lowest and is exposed to air only during extreme spring tides or storms.  The backshore zone is the highest and is exposed to water only during extreme spring tides or storms. 

Many species of animals live in each zone and are adapted to living completely submerged as well as completely uncovered by water for several hours each day.  They handle the change in temperature and salinity with exposure to air or water.  Tidal pools may keep some animals submerged for far longer periods.  Temperature, dissolved oxygen, and salinity change far less for these organisms. 

Bryozoans by John Turnbull, Sep 2021; Sea anemone by Barb Ignatius; Squat lobster, Glathea rostrata, by FWC Fish & Wildlife Research Institute, Aug 2013

Some species can be found in every zone in the ecosystem, but many are anchored to rocks or dug into the bottom.  Species may prefer one zone, but get washed into another zone by wave action.  Many organisms have tough outer surfaces to put up with battering waves and exposure to sun and wind.  All of the occupants are subject to a wide range of predators from those that move on dry land to underwater hunters.  Let’s take a look at a few of the creatures able to live in these ever-changing conditions.

The sea anemone clings to rocks and protects itself by drawing in its tentacles to become a jelly-like blob.  The squat lobster can be found under stones along the shoreline.  Its tail is fan-shaped and facilitates quick escapes when the animal is threatened by pulling the lobster through the water with powerful strokes.  Bryozoans are small filter feeding organisms protected by a hard exoskeleton that the animal can withdraw into for protection.

A mollusk called a dog whelk is a stealth predator often found on rocky surfaces.  It uses its tongue to drill through the shells of other mollusks, where it squirts a digestive juice into the prey’s shell which kills and partially digests the prey.  The dog whelk then uses its tongue to suck up the soupy meal.  The starfish is another fierce predator.  It wraps its arms around a shellfish and pulls it apart.  Upon opening the shell, the starfish pushes its stomach out of itself and into the prey’s open shell where it empties its digestive juices inside, and similar to the dog whelk, creates a tasty, soupy, meal.

Sea urchins can be found clinging to hard surfaces where they feed on algae and other small, encrusted animals.  Fan worms look like a leathery tube among underwater rocky crags.  Several feathery tentacles fan out into the water to filter out microorganisms flowing by.

Shorelines create a habitat that is constantly changing with tides moving in and out, inconsistent weather conditions, and a large variety of flora and fauna coming and going.  Learn more about this fascinating habitat at the Jurica-Suchy Nature Museum or a natural history museum near you.

^{Botanical beach at Port Renfrew by James Wheeler; Feather Boa kelp in the surf by Kqedquest, May 2007; Rocky intertidal zone in Oregon by Minustide, May 2015}