Know your beach-this week from the beach

#4 in the 2017 series of guest blog posts by Seattle Aquarium beach naturalists Bobby Arispe and Jen Strongin.

Alki Beach Park, South Alki, “the rocky side,” Constellation Park, Charles Richey Sr. Viewpoint—it may have a lot of names but this stretch of beach is one of my favorites in Seattle. A diversity of habitats are what makes it great for low-tide beach walks. On the south end, there’s a large boulder wall with so much life in every nook and cranny. We often see very large painted and plumose anemones, and find ourselves at eye level with purple sea stars and snappy barnacles. If you bring a flashlight to light up the dark crevasses, you can discover even more creatures that call this wall home.

Exploring the boulder wall.

Exploring the boulder wall.

A painted anemone retracts its tentacles as the tide goes out.

An anemone sags without the water to float in.

Next we have eelgrass beds and sandy flats. We always try to walk around, not through, the eelgrass beds. Eelgrass is a delicate home to kelp crabs, young salmon and other small fish. In the sandy gaps, between the grass, we see kelp crabs running around, decorated with little bits of green algae stuck to their backs. In the sandy flats a big treat for us is to find a moon snail. These large gastropods are voracious predators, using their drill-like mouths to suck clams from their shells. And they make something that causes one of the most frequent questions we get on the beach: “What are these gray plasticity looking things, are they trash?” Moon snail egg collars! They may feel like plastic and look like a toilet plunger, but they are made by these snails. Combining mucus, sand and millions of eggs, their distinct shape is formed by the moon snail’s body and shell. I love how excited people get when they learn about these. Plus they are home to so many smaller creatures.

Low tide on Alki beach.

A barnacle-eating dorid and a tiny skeleton shrimp on an egg collar.

A spaghetti worm who lost its tube home.

On to the long row of rocks that goes out into the water. This is the sweet spot for all kinds of creatures. This time we found something amazing: a huge gumboot chiton. This one was about 8–9 inches long and really camouflaged between two rocks. These chitons can grow up to 13 inches long and live up to 20 years. They also have a unique worm and tiny crab that often live in their underside flaps. And they have a radula (kinda like their tongue) that is coated in a hard magnetic material. All and all, a pretty cool meatloaf-looking critter.

A gumboot chiton hides between rocks.

Sharing our gumboot find.

A small blood star.

If you keep going north on the beach, you’ll encounter big, sandy tide pools with thousands of small aggregating anemones, and small rock ledges with dozens of lined and mossy chitons. Larger rocks at the far north end of the beach are always a happy home for lots of bright orange sea cucumbers and more brilliant purple sea stars.

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If it’s an extra special day, you could see a humpback whale breaching, playful harbor seals popping up, or ospreys and bald eagles dive-bombing into the water for a fish. All with ice cream and pizza just a short walk away. Alki Beach is a pretty special place.

A stubby rose anemone in a shallow tide pool.

A beautiful summer day on Alki.

Meet Seattle Aquarium beach naturalists on local shorelines this summer! Check our website for dates, times, locations and directions.

About Bobby:

This is Bobby’s second year as a beach naturalist.

His passion for the Salish Sea started when he and his wife moved to Seattle four years ago from San Antonio, Texas.

Bobby is an avid photographer and enjoys capturing his adventures of the Pacific Northwest. During the week you will find him biking to work where he leads a creative team at a local marketing agency.


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