Seattle isn’t just about coffee, grunge, and the Space Needle; its waterways host a hidden treasure trove of biodiversity, including some of the most dazzling marine creatures you’ll ever encounter—nudibranchs. These flamboyant sea slugs can be found within city limits, gracing tidepools and dock pilings with their vibrant colors and fascinating behaviors. From the shores of West Seattle to the bustling marinas of Shilshole Bay, here’s a closer look at the species you can encounter and where to find them.
Nudibranch Hotspots in Seattle
Fauntleroy Ferry Terminal
The Fauntleroy Ferry Terminal isn’t just a transportation hub; it’s also a prime spot for observing nudibranchs. The docks and rocky intertidal zones here are teeming with life.
White-Lined Dirona (Dirona albolineata): With its translucent body and glowing white lines, this species is a Fauntleroy favorite.
Nanaimo Dorid (Acanthodoris nanaimoensis): A delicate dorid with white papillae that look like they’ve been dusted with snow.
Barnacle-Eating Dorid (Onchidoris bilamellata): A voracious predator of barnacles, often found clinging to rocky surfaces.
Heath’s Dorid (Geitodoris heathi): A rare find, blending in with the substrate but worth the effort to spot.
Festive Tritonid (Tritonia festiva): This elegant species lives up to its name with its festive, frilly appearance.
Golden Gardens Park
Nestled in the northwest corner of the city, Golden Gardens Park offers an expanse of rocky tidepools and sandy shores, perfect for nudibranch hunting.
Monterey Dorid (Doris montereyensis): A sturdy dorid with a yellowish hue that thrives in the rocky tidepools here.
Northern Leopard Dorid (Diaulula odonoghuei): A patterned beauty that blends in surprisingly well with its surroundings.
Bell Harbor Marina
Bell Harbor’s docks provide an urban backdrop for spotting nudibranchs on pilings and other fouling communities.
Hooded Nudibranch (Melibe leonina): Known for its translucent body and unusual “hood” used for feeding, this species is a showstopper.
Giant Nudibranch (Dendronotus iris): A regal giant with elaborate cerata and a knack for making an impression.
Shilshole Bay Marina
Shilshole Bay Marina’s docks and seawalls are another hotspot, particularly for species that thrive in fouling communities.
White-and-Orange-Tipped Nudibranch (Antiopella fusca): A glowing nudibranch with vivid orange-tipped cerata, making it easy to spot.
Horned Nudibranch (Hermissenda crassicornis): A flashy species with orange rhinophores and electric blue highlights, frequently spotted in this area.
Seattle’s Star Nudibranchs
Horned Nudibranch (Hermissenda crassicornis)
The Horned Nudibranch is Seattle’s most ubiquitous species, found from Golden Gardens to the Fauntleroy docks. Its fiery orange and neon blue coloration make it an easy favorite among observers. It’s particularly fond of hydroids, so look for it near floating docks and algae-covered rocks.
Orange-and-White-Tipped Nudibranch (Antiopella fusca)
This elegant nudibranch adds a splash of vibrancy to Seattle's waters with its striking orange-tipped cerata and translucent body. Often found around marinas like Shilshole Bay, its vivid coloration and graceful movements make it a highlight for any urban tidepooling adventure. Keep an eye out for it near floating docks and algae-covered surfaces.
White-Lined Dirona (Dirona albolineata)
Arguably the most photogenic of Seattle’s nudibranchs, the White-Lined Dirona glows with a surreal, otherworldly beauty. Its shimmering lines and flowing cerata give it an almost magical quality.
Challenges and Rewards of Urban Nudibranch Hunting
Exploring Seattle’s waters for nudibranchs isn’t without its challenges. Urban environments can bring murkier waters, boat traffic, and less-than-pristine conditions. But the reward? A window into an underwater world that thrives despite the city’s hustle and bustle.
The nudibranch populations in Seattle reflect the resilience and adaptability of marine life. Species like the Horned Nudibranch and Hooded Nudibranch seem to flourish amidst urban development, serving as reminders of the rich biodiversity that exists just below the surface.
Tips for Spotting Nudibranchs in Seattle
Timing Matters: Low tides and calm waters make for the best conditions.
Gear Up: A flashlight and polarized sunglasses can help you spot these tiny gems.
Explore Carefully: Urban tidepooling spots are sensitive ecosystems—step gently and leave no trace.
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