Know your beach-this week from the beach

#3 in the 2018 series of guest blog posts by Seattle Aquarium beach naturalists Bobby Arispe and Jen Strongin.

Message from Jen:

Did you get out and explore our beaches this past week during some of the lowest tides we will have this summer? Our naturalists were out every day, mingling with our intertidal neighbors and helping our visitors see and learn about even the tiniest of creatures! Pictured above is a tiny animal, no bigger than the tip of your pinky finger, called a leather limpet. You can find these wondrous beings nestled into the seaweed or cavorting amongst the barnacles on the upper areas of the intertidal zone. Not really true limpets, leather limpets are more closely related to some of our other favorite beach dwellers, nudibranchs. They need air to breathe and are known to find trapped air bubbles, to use kind of like little SCUBA tanks, so they can breathe when the tide covers them up.

If you ever find a perfectly spherical, jelly-like, transparent blob on the shore, it might be a sea gooseberry. We got to see some on our West Seattle beaches this past week. sea gooseberries are comb jellies, not true jellies. They don’t have any stinging cells, instead they capture their prey with sticky pads on their tentacles. They have eight rows of “combs” covered in tiny hairs that they use to propel themselves through the water. If you are lucky enough, you might see one with the light hitting it just right to create a rainbow-disco-light show.


Another tiny member of the intertidal is the barnacle eating dorid nudibranch. Small but mighty, they use their drilling tongue covered in hundreds of sharp, tiny teeth (radula) to drill into barnacles and slurp them out like a barnacle soup.

We all like to nerd out over nudibranchs. They are a diverse bunch and range in size from teensy to football sized. Pictured above is a cryptic nudibranch, worthy of an I-spy hunt while you are out tide pooling! They eat kelp encrusting bryozoans (a moss animal), those beautiful, circular patterns you see on big blades of kelp. They look amazingly like their prey and can be very hard to spot. Once you see one though, you may start to see them everywhere.

Brittle stars are also among the tiny animals on our beaches. They prefer to stay hidden under the rocks where they can be protected from the sun and larger predators. We have 53 species of brittle stars in the Pacific NW! These are delicate animals that will shed their limbs if they feel threatened.

Beach Etiquette Tip – Don’t turn over rocks that you need more than one hand to lift and always return the rock exactly as you found it. Turning over large rocks means a greater chance that you may crush delicate animals and leave them exposed to predators. 

We have been seeing more and more green sea urchins on our local beaches. These spiny skinned animals are relatives of sea stars and sea cucumbers. They love to eat kelp but have also been known to scavenge other detritus too (it is good to be adaptable)! The urchin’s mouth has a jaw with five sharp teeth. It is referred to as Aristotle’s lantern as it reminded Aristotle of a five sided lantern made of bone common in his day. 

Moving on to some bigger friends, did you know some chitons are real homebodies? If you look carefully at rocks on the beach, you might notice some very distinctive, chiton-shaped bare spots. Some species of chiton have a “home base” that they return to every morning after a night of foraging. Over time, that special spot gets worn down, as they clamp down hard to keep themselves from being swept away by the currents or eaten by predators.

We love seeing stars on the beach. I have fielded many questions from visitors this season about how our local stars are doing after the devastating Sea Star Wasting Disease (SSWD) that wiped out 80% of some species up and down the West coast. There are still many unanswered questions regarding this disease. We are seeing some healthy stars on our beaches but are certainly still seeing some affected by SSWD . The top photo shows some gorgeous, healthy ochre stars we saw and the the second photo above is an arm of an ochre star, still clinging to the rock, the rest of the body gone, most likely a victim of SSWD.  If you are interested in reading more about the current survivors of this disease, the New York Times has a very interesting article in their science section this week.

I will leave you with a few more photos from the intertidal zone! We are so lucky to share our city with these beautiful creatures. We hope to see you out on the beach soon! If you have any photos of your own from your local beach explorations, be sure to tag them on social media with #beachnaturalist!

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

About Jen:

Jen writes:

“I ventured westward from Albany, NY and fell madly in love with our city from the moment I arrived. It was 21 years ago this August when Seattle first charmed me with its lush, forested parks, beautiful beaches, and water and mountain views (when the skies are clear enough) all around.

I signed up to be an interpretive volunteer at the Seattle Aquarium in 2013, became a beach naturalist volunteer in 2014, and this will be my third year as an official member of the Seattle Aquarium staff as a beach captain. My favorite place to be is on the beach, with my camera, sharing my love and knowledge of our intertidal dwellers with the hope that I will inspire others to love and protect the Salish Sea and the ocean beyond.”


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