Know your beach—season recap


#4 and final post in the 2019 series of guest blog posts by Seattle Aquarium beach naturalists Bobby Arispe and Jen Strongin.

A big “Thank you!” to everyone who came out to visit us on the beach this summer! We loved your curiosity and empathy for life on our beaches as well as hearing your stories about how you like to help take care of this incredible resource we call the Salish Sea. Another big “Thank you!” to all of our 280 beach naturalist volunteers who help to make this program so wonderful. You are such a passionate, dedicated group of people and are so appreciated by all of our beach visitors. We heard over and over this summer, “Thank you for being here!” and “Thank you for all that you do!”

I enjoyed looking back through all of my photos from this summer and seeing the great diversity of life on our urban beaches. Here’s a recap of some of the unusual and amazing animals I got to see this summer.

Hooded nudibranch

The nudibranchs! For the second year in a row, hooded nudibranchs, Melibe leonina, appeared in August at some of our local beaches. There were sightings at Seahurst, Carkeek and Saltwater. This one was about four inches in length. The “paddles” on the back are called cerata, and they contain branches of the digestive tract and gills for respiration. They use their oral hood like a fishing net, opening wide to sweep the water for tiny crustaceans and sometimes larval fish and mollusks. They like to swallow their prey whole as they do not have a radula, like many of their nudibranch relations.

Burrowing aeolid

A visitor found this tiny burrowing aeolid, Cumanotus sp. I have never seen this species on our beaches before, and quite frankly, had never even heard of it! The visitor found it on the sandy substrate at a very low tide on Seahurst Park Beach. Apparently it likes to burrow into the sand and is rarely ever seen.

Heath's dorid

We have several species of sea lemon here in the Salish Sea (at least, that I know of). This was the year we finally nailed down how tell some of them apart! This one is a Heath’s dorid, Geitodoris heathi. It can be distinguished from its look-alikes, the Monterey and noble sea lemons, by its smaller tubercles, or bumps, on its back and smattering of darker-colored spots as well as often sporting a larger dark splotch right above the gill plume.

Long horned nudibranch

I am trying very hard to not refer to this species as an opalescent nudibranch anymore. The trouble with common names is that sometimes different species may be referred to in the same way. There is a true opalescent nudibranch, Hermissenda opalescens, that you can find in California. Our local species, pictured above, is Hermissenda crassicornis, which translates to “thick-horned nudibranch.” Somehow, that moniker doesn’t capture the beauty of this animal, but it’s a more accurate common way to refer to this local species.

Taylors sea hare

We had lots of reports of Taylor’s sea hare sightings at our north-end beaches like Carkeek Park Beach and Richmond Beach. Even though it looks like a nudibranch, this sea hare is more like a nudibranch cousin. They make their homes on blades of eelgrass. These blades are encrusted with tiny diatoms that the sea hares like to eat, and they also use the blades as a surface for laying their rectangular egg packets. When they hatch, there is no larval phase; they are just teensy, mini sea hares. (Can you imagine how cute they must be?)

Giant flatworm

If you saw this in a tide pool, your mind might think “nudibranch,” but this one is a giant flatworm! It was the size of a large hand and very exciting to see out in the wild.

Spaghetti tube worm

Another type of worm we saw a lot of this summer was the spaghetti tube worm. These worms build delicate sand tube homes on the underside of rocks, where they hang out and wait for some delicious food to come by. They use their head of spaghetti-like tentacles to capture their prey. We try not to overturn any large rocks on the beach, as it disturbs animals like these worms and often destroys their delicate homes.

Painted anemone out of water

“What is that?” is a question that gets asked a lot when it comes to anemones at low tide. When they are out of the water, they look like alien blobs! They tuck in their tentacles to stay moist and are often distorted in shape by gravity pulling on their bodies as they hang off the rocks when the tide is out. The photo above and the photo below are the same animal, a painted anemone, one out of water and one in.

Painted anemone in water



Looking closely at the world beneath our feet on the beach and sharing what we see with visitors is always a highlight of the summer. Sometimes, when you stare at one spot for a while, the intertidal world reveals itself to be rich with life.


Although sea star wasting disease is still present, most of the stars we observed on our local beaches this summer looked good and healthy.

Mottled star
Mottled star


Leather star growing an arm
Leather star growing an arm


Midshipman eggs

Here are before and after images of the eggs of a plainfin midshipman. In a matter of weeks, the babies develop and start to hatch. They stay attached to their yolk sacs until their mouths develop and they are able to go off and feed on their own. This is another reason overturning large rocks is challenging for our intertidal friends. These delicate eggs and babies can be exposed to predators or crushed when the rock is turned back over.

Midshipman eggs hatching


Pacific red octopus

Some other sightings from our beach naturalists reports this summer have included Pacific red octopus, pink tritonia nudibranchs, harbor porpoises, minke whale, harbor seals, creeping pedal sea cucumbers, sunflower sea stars, striped sun stars, C-O sole, gunnels, big skates, living moon snails, crabs mating, pile worms, geoducks, osprey, bald eagles, bubble snails, noble sea lemons, Monterey sea lemons, gumboot chitons, tunicates, squid eggs and more. It was a good summer for sure.

It won’t be long until we’re out on the beach for some winter nighttime low-tide walks. You can keep an eye on this space for information about our winter programming. If you’re interested in joining us as a beach naturalist volunteer, we start our recruiting in process in February 2020. Shoot us an email at and we’ll put you on our contact list!

Looking for something fun to do this fall when tide pool season is over? Come visit our Cedar River Salmon Journey naturalists for a talk about salmon as they migrate home to spawn in the Cedar River.

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