A SMEA Student’s Guide to Tidepooling in Seattle

By Maddie Hicks

Spring in Seattle is well underway, with the promise of good weather and sunny days ahead. As we come out of our winter hibernations, what better way to celebrate longer, nicer days than to get outside and visit local wildlife? In Seattle, the perfect time to see subtidal marine critters in their natural habitat is in spring and summer when the lowest tides occur during peak daylight hours. Despite living in an urban city center, there are still many spots in Seattle where you can go to spend an afternoon tidepooling.

This Earth Day, another SMEA student and I popped on some rain boots and decided to visit Carkeek Park – the original homeland of Coast Salish people – to see for ourselves. It was the perfect way to honor the planet we live on and the creatures that live here, and we even encountered some species I had never seen before. 

This photo panel shows two photos of students in the tidepools. The photo on the left shows author Maddie Hicks crouched down in the rocks near a white bucket filled with creatures, including a small orange sea star and long worms. In her hand is a small white and orange clown nudibranch. The photo on the right shows student Courtney Moulton smiling at the camera while crouched in the sand at Carkeek Park Beach next to some seagrass. In her hand is a Red rock crab with its abdomen facing the camera and its claws extended out.
Author Maddie Hicks explores the tidepools in Friday Harbor with students during summer 2022 (left) and SMEA student Courtney Moulton shows off a red rock crab from Earth Day 2023 at Carkeek Park (right). Photo credits: Jessica Fergel (left) & Maddie Hicks (right), used with permission.

 

What is a tidepool?

Tides, the predictable diurnal or semidiurnal rise and fall of sea levels, are caused by the gravitational forces of the moon and the sun on the Earth’s oceans, though the moon is the primary driver. In our region we experience a semidiurnal tidal cycle, meaning there are two low tides and two high tides each day. Low tide occurs when the ocean recedes from the shoreline, leaving behind pools of water among rocks and on beaches that can vary from a few inches to several feet deep. These pools of salty ocean water that are left behind are called tidepools.

Animals that live on intertidal rocks and beaches are greatly impacted by the tides. Indeed, some animals will spend half their day submerged by water during high tides only to be exposed to the sun, air, predators, and low oxygen during low tide hours later. Despite this constant change, the animals that live here have adapted to living in shifting environments.

One of the primary adaptations that many tidepool animals have is the ability to withstand long periods of exposure to air when the tide recedes. Some animals, like sea anemones, are vulnerable to desiccation, or drying out. To avoid this, anemones retract their tentacles, contract their bodies, and close their mouths to reduce water loss. Other animals respond in ways to survive changing temperatures, tides, and predators. Hermit crabs and snails retreat into their shells or crevices to avoid dehydration, chitons and limpets hold tight to rocks to retain water within their shells, and sea stars hide their tube feet from predators by wedging themselves between rocks, in crevices, and in other hard-to-reach areas.

Protect yourself and the wildlife

Tidepooling offers a wonderful opportunity for us to see marine creatures in their natural habitats, but it is important to explore their homes safely and respectfully. Scrambling over slippery rocks and navigating the rising tide is no easy task and has the potential to be dangerous if you’re not careful. To prepare for a successful and safe tidepooling excursion, it is important to check the tide tables before leaving to properly time your adventure. I like to arrive at my tidepooling location about an hour before the peak low tide so I have plenty of time to explore before the tide comes back in. Other things to remember for your own safety are:

  • Bring proper close-toed shoes that you’re willing to get wet.
  • Remember the rocks and seaweed are slippery! Be careful where you step and tread slowly.
  • Never turn your back on the ocean and always watch the waves. Be careful of sneaker waves on open coastlines.
  • Watch the tides and the time. You do not want to be stuck or trapped somewhere when the tide comes back in.

Not only is it important to protect yourself while tidepooling, it’s also important to respect the delicate wildlife that lives in these ecosystems. If you’ve ever visited the touch tanks at the Seattle Aquarium, you know the rules are to gently touch the animals with one or two wet fingers. The same rules apply in nature. If you’re going to touch animals, do so gently. Other things to remember include:

  • Make sure to never remove animals from their homes or pry them off rocks as this can injure or kill them. Always leave the animals right where you found them (even shells can have a critter in them!).
  • If you flip over a rock to see what’s underneath, return the rock exactly where you found it and replace it carefully.
  • Watch your step as you navigate the rocky beaches to avoid stepping on animals tucked away in rock crevices, hiding in seaweed patches, or poking out from the sand.

Creature features

I would be remiss to talk about tidepooling without mentioning some of my personal favorite tidepool-dwelling animals that you might get lucky and see on your next adventure. Although there are several much more comprehensive guides online (like this Puget Sound Beach Guide), this article can serve as a starting point for learning some fun facts about the animals in our local tidepools. If you are out in the tides and stumble upon a creature that you don’t recognize, you can also snap a picture with iNaturalist for identification help.

Mollusks: nudibranchs, snails, chitons, limpets, clams, mussels, octopus

At the top of the list is my favorite animal, the nudibranch in phylum Mollusca. Animals in this phylum all have a mantle, or a mass of soft flesh that protects their internal organs, and many secrete hard shells at some point in their life stages. Gastropod mollusks, like nudibranchs and snails, have a strong stomach-foot and a radula, or toothed tongue, for scraping food off rocks.

Nudibranchs, or sea slugs, come in a stunning array of colors, patterns, and shapes. Many sea slugs can be found eating sponges on rocks, hiding in moon snail casings, or attached to pieces of kelp. When you’re searching for nudibranchs, be on the lookout for their distinctive colorful spiraled, ribbon-like egg masses attached to rocks – where there are eggs there will likely be a nudibranch, or two!

Fun fact: there is a type of nudibranch, called Elysia chlorotica, that can steal photosynthesizing cells called chloroplasts from the plants they eat and are able to store them for use in their own bodies, thus “photosynthesizing” for energy to supplement their food intake.

This photo panel includes four photos related to nudibranchs. Reading right to left, top to bottom, the first photo is a zoomed-in view of a yellow spiral egg mass on a rock. Each small egg looks like dots covering the spiral mass. The photo to the right is a zoomed-in photo of a shaggy mouse nudibranch out of water in the hand of a student. The nudibranch is a creamy color with brown cerata covering its body. Out of the water, these lay flat against the nudibranch's body. On the bottom left, a student holds six individual nudibranchs in their hands. Two of the nudibranchs are brown blobs with leopard-like spots on them. The other four are yellow blobs with brown freckles. To the right is a zoomed-in photo of a yellow nudibranch on a rock under a barnacle. This nudibranch is the same as the yellow ones in the other photo but shows a closer view of one individual.
Various species of nudibranchs (sea slugs) that were found in Friday Harbor and Carkeek Park. On the top left, is a photo of nudibranch egg casings, courtesy of Anna Barnett, shared under a Creative Common’s License. Below that, a student holds several spotted leopard dorids and sea lemons. On the top right, a student holds a shaggy mouse nudibranch. Below that is a single sea lemon on the rocks. Photo credits Olivia Carpenter (top right & bottom left) & Maddie Hicks (bottom right), used with permission.

 

Other gastropod mollusks you might see in the tidepools are snails, like the common herbivorous periwinkle snail, or carnivorous snails like the whelk, which have spiral shells reminiscent of land snails. Limpets, too, are snails, though their shells do not exhibit spirals and instead look more like pointed caps. Look out for chitons, too—more primitive gastropod mollusks that cling to rocks with their strong foot.  Bivalve mollusks, such as mussels and clams, have two shells joined at a central hinge. Mussels use protein-rich threads to attach to rocks and dock pilings, and clams bury themselves in sediments on beaches and mudflats.

This photo panel shows three photos of mollusks. The photo on the left shows a large, head-sized cream shell of a snail with several inches of the snail's mantle protruding from the shell. The animal is in the wet sand surrounded by seagrass. The two photos on the right are of different chitons. The top right photo shows a camouflaged chiton on a rock. The color of the plates on the back of the chiton matches the dark rock color and the mantle of the chiton is covered in what looks like hairy moss that also blends in with the rock, giving it the common name "mossy chiton." The chiton on the bottom right is on a small rock in the hand of a student. This chiton has bright blue, purple, and white plates and is easy to spot on the surface of the dark rock.
Gastropod mollusks use their strong foot to hold tight to the rocks and substrate. A large moon snail found at Carkeek Park uses its foot to move around the tidepools (left). Chitons, another gastropod mollusk, also have a muscular foot. Some chitons, like the brightly colored one on the bottom right, are easier to spot than the well disguised mossy chitons that blend into the rocks (top right). Photo credits: Olivia Carpenter (bottom right) & Maddie Hicks (left & top right), used with permission.

 

Arthropods: barnacles, crabs, hermit crabs

The Arthropod phylum consists primarily of crustaceans, or various types of crabs and lobsters which are important species for both Puget Sound fisheries and the traditional foodways of Coast Salish Tribes. You are certain to see smaller shore crabs hiding under rocks and scavenging for food in tidepools and might even see some bigger species like the kelp crab, Dungeness, or red rock crab. Also in this group, though found higher up on beaches and dock pilings, are barnacles. When barnacles are submerged in water, be sure to watch for their feeding tentacles fanning the water from their protective shells looking for food in the water column.

This photo shows a zoomed-in view of a professor standing in the tidepools. Just the torso and legs of the professor can be seen. He holds one large crab in each hand, both with the under abdomen facing the camera. The left crab has a wide rounded abdomen for carrying eggs, indicating it is a female crab. The crab on the right has a thin triangular abdomen, indicating that it is a male.
A professor from Friday Harbor Labs holds two large Dungeness crabs found in the tidepools, both a female and a male. The female crab on the left has a wide, rounded abdomen for carrying eggs. The male on the right has a more narrow, triangular abdomen. Photo credit: Syona Rajagopalan, used with permission.

 

Echinoderms: sea stars, brittle stars, sea urchins, sea cucumbers

Echinoderms are the animals that many people imagine when they think about tidepools because they are very common and easy to find. The phylum is characterized by body plans that have five-part radial symmetry instead of the typical bilateral symmetry common to humans and many other animals. The group includes sea stars, urchins, and sea cucumbers.

Sea stars are abundant in tidepools and come in various sizes and colors. The primary sea stars you will likely see in Puget Sound include the ochre sea star, which was a species decimated by sea star wasting syndrome in 2014. Their renewed abundance in Puget Sound is a positive indication that their population is recovering. Ochre sea stars are about the size of your hand with rough backs and can be orange, purple, or brown. Other sea stars you might see include the smaller, smooth, bright orange blood star or the slick leather star, which smells like gunpowder!

Other popular tidepool-dwelling Echinoderms include the sea urchin, the spikey purple, red, or white animals that live among rocks and are often found in touch tanks. Sea cucumbers are also common and can range in size from less than an inch to over six feet long, though these long forms are primarily tropical. The ones in Seattle are usually on the smaller end, but California sea cucumbers can be up to two feet long. Sea cucumbers have tube feet they use to traverse the ocean floor and retractable feeding tentacles for collecting food.

Fun fact: raw sea urchin gonads (or sex organs) are edible and are considered a delicacy in many parts of Asia. This dish is called uni. Sea cucumbers are also edible delicacies in many areas of the world and support the food security of seaside communities.

This photo panel shows three different species of sea stars. On the left, a student holds a large leather star with two hands. The base color of the star is olive green with red and orange markings over the top. All five arms are spread out. The central photo is a zoomed-in view of a small, smooth, bright orange blood star on slimy seaweed. This sea star is a few inches across with extended arms and is uniform in color. On the right, a hand-sized purple ochre star is wedged under a rock with its arms pulled close to its body. The sea star clearly has a bumpy and rough surface.
Sea stars that you might find include the leather star (left), the blood star (center), or the ochre star (right), which might be orange, purple, or brown. Photo credits: Maddie Hicks, used with permission.

 

This photo panel has two photos of tidepool animals. On the left is a zoomed-in view of a rock crevice. Lodged in the cracks are three orange-red tube-like creatures that are short and thick and are only partially seen coming out of the crevice. These are sea cucumbers with their feeding tentacles retracted. Dark orange lines indicate the five-part radial symmetry these animals have. To the left of the cucumbers in the same photo is a white-yellow small, curved, calcareous tube. Peeking out the end of the tube is a small orange-red nub, which is the tip of the feeding tentacles of a well-hidden feather duster worm. The photo on the right shows a zoomed-in view of two spikey purple urchins under a rock crevice. They are partially submerged in the water.
Sea cucumbers, like the orange Cucumaria (red sea cucumber) hide in rock crevices, like this one at Carkeek Park. Sometimes the cucumbers will show their feeding tentacles, but this cucumber has them hidden. Sharing the rock with the cucumber is a tube worm, which is a type of Annelid. This one lives in a calcareous tube and is a serpulid. On the right are two purple sea urchins, another common tidepool find. Photo credits: Maddie Hicks (left) and benketaro (right), used with permission and shared under a creative commons license.

 

Cnidarians: sea anemones, jellyfish, corals

Another touch tank favorite that many are familiar with is the sea anemone of the phylum Cnidaria. Animals in this phylum tend to be soft and squishy and are characterized by stinging cells, called nematocysts that are used for defense and food capture. These nematocysts give jellyfish their sting and help them collect food. The stinging cells are also found on the tentacles of anemones. Sea anemones are safe to touch but you might notice they “stick” to your finger. The “stickiness” is actually the nematocysts stinging you, but thankfully humans have thick enough skin on our hands that we don’t feel the sting the way an unsuspecting fish might. Anemones can be either solitary or aggregating – meaning many may grow together in one place – and can be found in tidepools and on dock pilings.

This photo panel shows two photos of different species of anemones. On the left, a rock is completely covered in green slimy blobs, which are the aggregating anemones with their tentacles tucked inside and their bodies contracted to be small on the rock. Little to no rock surface can be seen in the cluster. On the right, a zoomed-in photo of a large solitary anemone hangs off a rock. Half the tentacles can be seen on the bottom of the photo and the other half are not visible. The anemone is a pale olive green color with spots of red on the body column.
Sea anemones can either be aggregating, like the closed anemones (Anthropeura elegantissima) covering a rock on the left, or they can be large and solitary, such as the large anemone on the right. Be sure to check out their tentacles when they are open in the water. Photo credits: Maddie Hicks (left) & Olivia Carpenter (right), used with permission.

 

Others: tunicates (sea squirt), Porifera (sponges), Nemerteans (ribbon worms), Annelids (polychaete), vertebrates (tidepool fish)

There are many animals that you might see in the tidepools, and this list is not exhaustive. In fact, tidepools have such a wide variety of creatures that even if you visited the same site every day you are bound to find something different each time. Though the animals listed above are common finds, there are many other species waiting for you to find them. Some of them include marine worms like Annelids and Nemerteans. Annelids can either be errant or found dwelling in tubes on rocks or on docks. They are distinguished by their segmented bodies, whereas Nemerteans are often long and smooth-bodied. Sponges, which are an animal, are usually found on rocks and are a wonderful food source for many nudibranchs and other animals. Finally, you are bound to stumble on some tidepool fish as well, such as gunnels, pricklebacks, sculpins, and clingfish.

This photo panel includes four photos of common tidepool organisms. Reading top to bottom, left to right, the first photo is a zoomed-in view of a scale worm on someone's hand. The worm has distinct segmentation and "false feet" called parapodia. To the right is a photo of a yellow sponge expansively covering a rock. Excurrent siphons stick out and look like small yellow volcanoes. The photo on the bottom left is a small tidepool fish in someone's hand. The fish is long, skinny, and is a shiny dark brown color. It looks like either a prickleback or a clingfish, though the identification is unknown. The final photo shows a very long, skinny, red ribbon worm spread out over two hands. The worm is so long that the entire thing cannot be held in just two hands and it spills over the side.
Other animals you might find in the tidepools include Annelids like the scale worm in the upper left, sponges from phylum Porifera like the yellow sponge in the upper right, vertebrates like this tidepool fish in the lower left, and Nemertean worms, like the red ribbon worm in the lower right. Photo credits: Olivia Carpenter, used with permission.

 

Tidepooling in Seattle

Now that you are familiar with tidepool etiquette and some of the many wonderful creatures we have in our local tidepools, it’s time to get out and explore for yourself. Remember, check the tides and the weather and pop on your best pair of rainboots before you go. Be sure to awaken your inner child’s sense of curiosity and be prepared to get dirty searching under rocks and in crevices. You can either explore some tidepools outside of Seattle, like the ones in Friday Harbor or on Bainbridge Island, or you can stay local. Some tidepool spots you can explore in Seattle include:

  • Carkeek Park
  • Discovery Park
  • Golden Gardens
  • Constellation Park
  • Alki Beach Park

For more information about barriers to tidepooling and accessibility, see this past Currents article from our former Editor in Chief, Gabriela Carr.