Alki beach

Here in the Puget Sound region, we’re so fortunate to have miles of beaches to explore while maintaining the physical distancing that protects everyone’s health. And, better yet, we’ve got some upcoming low-tide days that will offer the perfect opportunity to explore the intertidal zone—the strip of land between high and low tide—to discover the amazing creatures that live there.

Puzzled about exactly what you might be looking at? You’re not alone! So here’s a head start: in no particular order, 10 of the incredible animals commonly found in the intertidal zone.

Aggregating anemone

1. Aggregating anemone
These beautiful animals look like undersea flowers—and they get their names because they can clone themselves and form masses (or aggregations). Look for them attached to rocks; they’re about 2” in diameter. It’s fine (and fun!) to gently touch them with one wet finger.

Hairy chiton

2. Hairy chiton
Those mollusks can grow to be up to 3” long and get their names from the soft bristles on their perimeter. Their small size belies their cool superpower: they have an internal compass that allows them to navigate at night!

Keyhole limpet

3. Keyhole limpet
This mollusk with the volcano-shaped shell even has a hole on top like a volcano on Earth does! This is a unique feature in limpet species. Another way that they’re unique is that, unlike most limpets, they’re primarily carnivores. Their shell width can be up to 2¾”.

Moon snail

4. Moon snail
Ever seen what looked like a gray toilet plunger on the beach and wondered what it was? It’s a moon snail egg collar, composed of up to 500,000 eggs, sand and mucous. Moon snails themselves may be harder to spot—even though they’re among the largest intertidal snails.


5. Periwinkle
These tiny (up to 5/8” wide), spiral-shelled snails are found on rocks and barnacles in eelgrass, seaweed or on rocky shores. Although their shells come in a variety of colors, they’re all the same species.

Shaggy mouse

6. Shaggy mouse
It’s a lucky day at the beach if you spot one of these sea slugs, resembling a wet mouse and coming in at about the same size: up to 2¾” long. If you happen to see what looks like a pile of soft, white noodles nearby, those are shaggy mouse eggs! 

Pacific geoduck

7. Pacific geoduck
First things first: do you know how to pronounce the second word in this animal’s name? It’s gooey-duck, go figure! The only part of this giant clam that you’ll see at the beach is the top of its neck, which can exceed 3’ (!!), extending about an inch above the surface of the sand. It’s fine to gently touch (and you may get squirted!) but pulling on a geoduck’s neck may kill the animal and end its up-to-150-year lifespan.

Hermit crab

8. Hermit crab
These small, up-to-1½” crustaceans use empty snail shells for their homes. As they grow, they move into larger shells. Find them by gently picking up snail shells and looking for the crab’s legs protruding from within. If you’re lucky, you may see a hermit crab walking below the surface of a tide pool!

Acorn barnacles

9. Acorn barnacle
These shrimp-like animals are housed in hard shells attached to rocks and other hard surfaces and can be up to ¾” in diameter. Look for them feeding underwater, using their legs (or cirri) to sweep up plankton.

Purple sea star

10. Purple sea star
These animals can actually be orange or brown in addition to their namesake color. They usually have five arms and can grow to be up to 14” across. If you touch one, do so gently, with one wet finger and without picking it up—picking up a sea star can injure the animal.

Interested in learning more? Download our Puget Sound Beach Guide to discover dozens of tide pool animals, with photos and info to help you identify them and fast facts about each. Curious about an animal that you can’t identify? Take a photo and email it to us at—one of our naturalists will respond to you as soon as they can!

The Beach Naturalist program is generously sponsored by the King County Flood Control District, Lake Washington/Cedar/Sammamish Watershed Salmon Recovery Council, Seattle Department of Parks and Recreation, The Boeing Company, The City of Burien, The City of Des Moines, The City of Shoreline, Washington State Parks and the Watershed Ecosystem Forum for WRIA 9. Thank you!



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