Know your beach—this week from the beach

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

The beach naturalists are back and rocking our new, ocean-blue-colored hats! We had so much fun exploring with all of you who came out to visit us the first week of this month as we kicked off our season. Here are just a few of the amazing animals that live in our intertidal zone and that we got to visit with when the tide was out.

Beach Naturalists at low tide


One of my top tips when you visit a tide pool neighborhood is to be mindful of the homes on the beach! This fish who laid these eggs is called a plain fin midshipman. The males make their home nest under the rocks and “sing” to the females to invite them over for a “date.” Several females may lay their eggs in the den of a crooning male midshipman. The ladies leave the new dad in charge of guarding and caring for the eggs until all the little ones hatch out.


Plainfin eggs


Turning over large rocks exposes the dads and eggs to the heat of sun, predators and the risk of crushing everyone when and if the rock gets put back in place—which is why we always advise beachgoers to leave large rocks undisturbed.

Lots of our local marine species lay their eggs in the spring and summer. We saw quite a variety on our beaches.


Moon snail egg collar


Looks like trash? Nope! These are eggs. Half a million moon snail eggs, to be more precise! Made of sand and eggs with mucous to glue it all together, these moon snail egg cases are true works of art.


Moon snail on beach being touched with one finger by a naturalist


Moon snails are pretty amazing animals—with their giant, slimy foot, tongue covered in sharp teeth for drilling through clams and mussels, and perfect whorl! We love getting to greet them on the beach with one gentle, wet-finger touch.


Polychaete eggs in sand


Moon snail egg collars provide a sheltered space for other animals to lay their eggs too. This wonderful green spiral is a mass of polychaete worm eggs on the underside of a moon snail egg collar.


Pair of sea lemon slugs


Dorid nudibranchs of all kinds lay wonderful egg spirals too. This sea lemon egg mass wasn’t too far from the animals that may have created it.


Sea lemon eggs


Fish eggs on the beach can found on rocks, eelgrass and all types of seaweeds. Bring your hand lens with you and check out some fish eggs up close. Sometimes they’re far enough along in their development that you see their cute little eyeballs!


Fish eggs on eelgrass


While many marine animals lay their eggs and leave the scene, mama crabs are all about attachment parenting! They have specialized, feathery “legs” to hold their eggs close to their bodies until the babies are ready to go off into the world on their own.

Cluster of bright orange eggs on crab's underbelly


We were happy to see some healthy sea stars on our beaches—both adults and babies. We even had a sunflower star sighting at one of our North End beaches, and it was a big, healthy adult!


Ochre sea stars under rock


Mottled sea star


The warm weather and just-right currents brought bunches of jellies onto our beaches. One of the most frequently asked questions we get is, “Will it sting me?” All true jellies sting, so taking pictures and observing with your eyes is the best way to check them out!


Lion's mane jellyfish


The lion’s mane jelly is one of the biggest jelly species in the world! They have a painful sting which is still potent even when they’re dead…yikes!


Water jelly


Water jellies are small and almost translucent with radiating “spokes” around the bell. Three scientists won the Nobel prize for discovering that these jellies have GFP, or green fluorescent protein. Scientists use this protein to light up the inner workings of cells to study them.




Although it looks like a true jelly, this ctenophore (teen-o-fore) or “comb jelly” is classified in its own phylum. This was probably one of my favorite unusual finds on the beach this past low tide. Unlike true jellies, ctenophores don’t have any stinging cells. Instead, they capture their prey with sticky tentacles or, as in the case of this beroe ctenophore, they just open their big mouth and swallow their food whole! If the light catches them just right, the tiny hairs they use for locomotion refract the light and create beautiful rainbows that radiate up and down their body.


Pacific red octopus


There were a few octopus sightings on our beaches too. I’m always a sucker (pun intended) for any octopus on the beach! This one was a small Pacific red octopus. They only reach about one or two pounds in size and live for a short one to two years. They may be small, but they pack a nasty bite with their sharp beak and venom. If you ever encounter an octopus on the beach, make sure not to handle it!


Couple and child on the beach


Come join us on the beach this week! All our locations, dates and times are listed on our website. Make sure to tag your amazing beach finds on social media with #beachnaturalist or #seattleaquarium. We can’t wait to explore more with you!


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