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A world of wonder: Celebrating invertebrates at low tide

Puget Sound at low tide is a joy well known to many in the region. It’s a formative experience for many children here, overturning rocks to see all the tiny crabs and sea stars that live amidst colorful seaweed, kelp and barnacles.

But few people are as versed in the lesser-known critters that live in the tidal zone as Seattle naturalist Kelly Brenner. She specializes in anything without a backbone. Brenner is the co-founder ofan online event called #Invertefest, which challenges anyone who wants to take part to find and help document the lesser-known or less-celebrated creatures in our midst. She also wrotea recent field guide to Seattle,which includes chapters on marine life.  

We waded into the saltwater together during a recent low tide at Constellation Beach, near Alki, so she could show me around — and introduce me to some of her favorite invertebrates.

“It's a very diverse beach,” she commented as we crossed a field of slippery sea lettuce before reaching more solid, sandy ground.

“We have the rocky kind of jetty here. We've got the sand with the eelgrass tide bed or beds. And then further down that way, we've got some more rocky structures that have little nooks and crannies that all the invertebrates love to hide in,” Brenner said.","_id":"0000017a-8d23-d4f4-a97b-af2b0e530000","_type":"035d81d3-5be2-3ed2-bc8a-6da208e0d9e2"}">" style="color: var(--ytcp-link-color); font-family: Roboto, Noto, sans-serif; font-size: 15px; white-space: nowrap;" target="_blank">","_id":"0000017a-8d23-d4f4-a97b-af2b0e530000","_type":"035d81d3-5be2-3ed2-bc8a-6da208e0d9e2"}">

The large, flashy sea stars that I remember from beachcombing in my youth are absent here. But Brenner leads me to see things I never knew where there. We walk over sand-colored aggregating sea anemones that have retracted their tentacles because the tide is out. To me they resemble tiny donuts in the sand — that could be easily overlooked.

“They’re closed up, their tentacles are all sucked in,” she says. “But when the tide comes in, the tentacles come out and they’re very colorful — they’re greens and pinks. In some places they’re so abundant, it’s hard to not step on them.”  

Sea anemones illuminated with a black light during a nighttime low tide,  at Constellation Beach in Seattle.
Credit Kelly Brenner
Sea anemones illuminated with a black light during a nighttime low tide, at Constellation Beach in Seattle.

And at night, she says many of them are iridescent and will glow if you shine a blacklight on them. “They glow in the dark. You walk around the beach with your light and it’s like fireworks.”  

Brenner carries a pen light and magnifying glass with her, so she can see and study things, even when they’re tucked away. She shows me sea pens tucked between the rocks, feeding, and chitons that are so flat you could almost overlook them. And then we start talking about worms.

She points to what looked to me like a tiny bit of shriveled up brown scum and tells me I am looking at a flatworm.

“You see it? It’s moving,” she says. Once she points it out, I watch it stretch itself out, magically transforming into a half-inch-long, coral-colored creature sliding along a rock.

And they have two little goofy eyes that look like comic book eyes. They don't really see. They just mostly see light. That's why it's moving now. It wants to go back where it's dark,” she says.

A flatworm, with it's cartoon-like eyes, seen here at at Foulweather Bluff in Hansville, WA.
Credit Kelly Brenner
A flatworm, with it's cartoon-like eyes, seen here at at Foulweather Bluff in Hansville, Washington.

She adds that if you cut a flatworm in half, you’ll have two. And if in fourths, you’ll have four. “They will just keep reproducing themselves as many times as they’re cut,” she says.

“There’s tons of really cool worms out here — I love the worms. I got really into them last year,” she says. 

For Brenner, that means she starts reading and studying up — typically by getting a detailed field guide, on a single subject, and pores over it for hours at a time.

So I just say oh, there's that and there's that and there's that. And I want to see that, too,” she says, adding that she has a favorite series, from the British Columbia Provincial Museum.

“They’re based in B.C., but of course, they're pretty good for here to have, like a whole book just on barnacles,” she says. There's so many good resources. You can really, really, really get in-depth on any sort of particular thing. Seaweed. There's an app for that now!”

Her most recent obsession is a kind of sea slugs, called nudibranchs. “And you think of the land slugs — which I like, but a lot of people think they're gross and slimy — but nudibranchs are gorgeous,” she says.

Seeing them can be tricky, because they’re most visible and interesting when they’re underwater. Brenner has an underwater camera.

A nudibranch, the White-lined Dirona (Dirona albolineata), photographed by Kelly Brenner at Constellation Beach, near Alki, in Seattle.
Credit Kelly Brenner
A nudibranch, the White-lined Dirona (Dirona albolineata), photographed by Kelly Brenner at Constellation Beach, near Alki, in Seattle.

“They are tons of colors. Some of them are translucent. They're oranges. Some are black. Some are pink. And they have cerata on their back, which are like little fingers,” she says. “They're just absolutely fascinating creatures… that are just unlike anything else.”

And yet, she feels that these worlds of invertebrates she’s discovering are not getting their due.

“ There's a lot of us on Twitter and other places that feel like invertebrates don't get the attention that they deserve,” she says. When invertebrates are, what, 95 percent of all animal life and what gets all the attention? The mammals, the birds, fish, everything with a backbone. And so we're always fighting Team Invertebrate for this grand injustice of invertebrates, not getting the attention that they deserve.”  

That’s why they created the online interactive event, #Invertefest. The organizers want you to find invertebrates anywhere around you — in your yard, a park, at the beach or a nearby alley — and share them on Twitter or another form of social media.  

The idea is to learn and help document all that is there — from dragonflies and spiders to sea slugs and slime molds, even flies.

Brenner says you don’t need a degree to make an impact. Citizen scientists can play a big role. The next Invertefest starts on Friday.

You can learn more about Kelly Brenner's work and her recent book, "Nature Obscura: A City's Hidden Natural World," in this webinar from KNKX and Mountaineers Books, How to Be A Backyard Naturalist

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to