Sea slugs make a splash at Deception Pass

Published 1:30 am Friday, July 24, 2026

With their bright colors and blob-like bodies, sea slugs, also called nudibranchs, were the star of the show at a mini pop-up aquarium event at Deception Pass State Park.

This was the third in a series of free mini pop-up aquarium events being held every Tuesday from 2-4 p.m. through Aug. 4 at the Rosario Beach Discovery Center, with each event showcasing a different marine animal.

Jamie Andersen Fields, a researcher at Rosario Beach Marine Laboratory, said funding for the pop-up aquarium series came from a grant provided by an anonymous donor through the Versacare Foundation. Fields explained these events are important for engaging with and educating the public.

“We want to be able to connect the local community with these beautiful creatures that are their neighbors,” Fields said. “And so by doing these events, we hope to be able to inspire the next marine scientists locally, but also just connect people with these animals that also call Fidalgo and the wider Salish Sea their home.”

The event featured a leopard dorid, a sea lemon and a rock with red sponge dorid eggs attached to it. People could also view sea lemon eggs under a microscope.

Fields said that, as dorids, the two featured sea slugs breathe through a plume of gills located at the back of their body, which they referred to as a “butt ruffle.”

“A lot of people were appreciating seeing how fun that looks,” they said.

The slugs also have a pair of ear-like organs called rhinophores on their heads that are used to sense the world around them, such as scents that are dissolved in the water. Sea slug eggs are encased in ribbons called rosettes, which can be up to several inches long. To put the sea lemon eggs under the microscope, Fields said a small section of the ribbon was removed.

Fields noted that sea slugs can commonly be found in local tide pools.

According to Fields, the slugs on display were collected by scientific divers off of Sares Head and are being used by student researchers for a project studying how changing ocean temperatures impact sea slug feeding behaviors. The slugs will be released back into the ocean at the end of the summer.

There will be additional mini pop-up aquarium events at the Rosario Beach Discovery Center on July 28 and Aug. 4.

The Rosario Beach Marine Laboratory will also be hosting their third annual pop-up aquarium from 12-4 p.m. on July 26 at The Patio of Dockside Dogs in Anacortes. The event is free and will feature one or two octopuses, a jellyfish tank, an eelgrass meadow tank, a touch tank and a microscope demo.

“We don’t all get the opportunity to to go down and be in the tide pools or know that these animals exist,” Fields said, “so we’re just sharing appreciation for our neighbors and giving back to the community that we live in.”