The picture shows a close-up of a textured surface, of an abalone, lying on sandy ground. The shell has a rich, dark brown color with streaks of a lighter brown and patches of red and white. The sand surrounding it is a mix of coarse grains and small pebbles in various shades of beige, brown, and some specks of pink. There are also some thin, dark brown seaweed strands scattered around.
What is in the Tidepools

What’s in the Tidepools? – December 2023

The picture shows an underwater scene with a focus on a large, dark-colored eel hiding among rocks and marine vegetation. The eel has a smooth, elongated body and its head is visible with a slightly open mouth and a clear, round eye staring towards the viewer. The surrounding rocks vary in size and color, ranging from light beige to dark brown, and are partially covered with what appears to be algae or marine growth.

What’s In the Tidepools? – December 2023

(NPS Photo/M. Rose)

December was a busy month in the tidepools. King Tides, high surf, holiday visitors, negative tides, jet skis stuck in shallow water and great weather allowed for fantastic viewing in the rocky intertidal. December’s highlights include, octopus, keyhole limpets, sea stars and more. Here is a sampling of what our volunteers observed during this month — thank you to everyone who contributed. Remember to send in your photos; we truly appreciate sharing them with everyone.

Don’t forget to visit the Tidepool Videos page.

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Keyhole Limpets were very prevalent this month. VIP Denine said visitors first thought the Keyhole Limpet she observed was a turtle!

Did you Know? Keyhole limpet hemocyanin (KLH) is a vital protein used in creating antibodies for research and medicine. It helps stimulate the immune system’s response to small substances, called haptens, that are usually not recognized by the immune system. KLH is favored because of its large size, which triggers a strong immune response, and its origin from a limpet, a type of sea snail, makes it less likely to cause errors in research involving mammals.

The picture shows a close-up of a dark brown or black slug with an orange underbelly, resting on a bed of vibrant green long thin blades of grass. The background is softly blurred with hints of greenery and sunlight, suggesting a natural, outdoor setting. The focus is on the slug, which is in sharp detail, highlighting its smooth, shiny texture and the contrast between its dark body and bright underbelly.
NPS Photo/P. Geisler – Keyhole Limpet
The picture shows a close-up of a oval shaped flat snail, with a smaller oval shaped shell partially visible on top. The shell has a spiral pattern with concentric circles in shades of brown, tan, and pink. The creature's body is a fleshy brown color, and it appears to be attached to a rock or a hard surface. There are some marine plants and small pebbles surrounding it. The center of the shell has a dark opening, possibly the entrance to the snail's interior.
NPS Photo/D. Wieder – Keyhole Limpet
The image shows a rocky beach scene with a close-up of a small crevice between rocks. Inside the crevice, there is a bright orange snail. The rocks surrounding the snail are gray and brown with various textures, and there are small pebbles and bits of seaweed scattered around.
NPS Photo/H. Marquez – Keyhole Limpet
The picture shows a close-up of a oval shaped flat snail, with a smaller oval shaped shell partially visible on top. The shell has a spiral pattern with concentric circles in shades of brown, tan, and pink. The creature's body is a fleshy brown color, and it appears to be attached to a rock or a hard surface. There are some marine plants and small pebbles surrounding it. The center of the shell has a dark opening, possibly the entrance to the snail's interior.
NPS Photo/D. Wieder – Keyhole Limpet
The picture shows a close-up of a brown and beige patterned oval shaped snail resting on vibrant green seagrass. A smaller oval shaped shell is on top with a hole in the center. The texture of the shell appears rough and weathered. The seagrass is thick and lush, providing a contrasting backdrop to the shell's earthy tones. The sunlight casts a bright glow on the scene, highlighting the natural details.
NPS Photo/D. Orr – Keyhole Limpet at the Zone 1/2 bend
A flat oval shaped snail resting on a bed of long thin blades of grass. The snail has a spiral shape with ridges and is dark brown in color. It's centered in the image and the blades of grass provide a vibrant green contrast to the snail’s earthy tones. The sunlight casts a warm glow on the scene, highlighting the textures of both the snail and the grass.
NPS Photo/D. Hunt – Keyhole Limpet

Octopus sightings were common during December and as always the visitors were excited to see them. Check out this octopus video from CVA Hannah.

Did you see the recent Cabrillo Field Note about the Two-Spot Octopus?, It was written by 13 year old Conservation and Environmental Stewardship Apprentice Izzy Song.

The picture shows a close-up view of a tidepool. The water is clear, allowing visibility of the sandy bottom with small rocks and pebbles. There are various marine plants and algae in shades of brown and dark yellow, with some having long, smooth, strap-like fronds, while others are more branched and bushy. Patches of pinkish-red coral-like vegetation add a pop of color to the scene. Sunlight reflects off the water's surface, creating a sparkling effect.
NPS Photo/S. Kristiansen – Two-Spot Octopus
An octopus partially covers a crab. Pink algae surrounds the octopus.
NPS Photo/M. Rose – Two Spot Octopus with Crab
The picture shows a close-up of a tidepool. There are various marine elements visible: - A large, reddish-brown crab in the center, blending with the rocks. - Surrounding the crab are pinkish coral-like plants. - There are also some green and yellow seaweed elements. - The water is clear, reflecting some light, and you can see the textures of the rocks beneath.
NPS Photo/M. Rose – Two Spot Octopus with Crab. Octopus arm (not tentacle) at the top of this photo.

Visitors are often asking to see Sea Stars in the tidepools. Well December didn’t disappoint.

The bat star has eyespots at the end of each arm that can detect light and uses sensors on its tube feet to “smell” prey. When a bat star finds a food item, it extends one of its two stomachs (the cardiac stomach) outside of its mouth cavity. The bat star then uses digestive enzymes to begin breaking down its prey. Eventually, the bat star pulls its cardiac stomach and partially digested prey back into its body to complete digestion.

The image shows a sea star resting on a rock submerged in shallow water. The sea star has a rich purple color with patterns of white dots surrounded by a lighter purple hue, creating a striking contrast. The rock is a dull gray with speckles of lighter shades, and there are other rocks visible in the background. The water is clear, allowing a detailed view of the sea star and the rock's surface.
NPS Photo/D. Wieder – Knobby Sea Star
The image shows a tidepool scene with various marine life. There are two sea stars, one large and bright orange, and a smaller one that is also orange but with a lighter shade and some white spots. Both sea stars have five arms and are resting on rocks. There are also two sea anemones visible; they have greenish bodies with a pattern of concentric circles and tentacles that are white tipped with pink. The tentacles are extended out, suggesting they are underwater.
NPS Photo/D. Wieder – Bat Stars with Solitary Anemones
The image shows a shallow body of water with a clear view of the rocky bottom. There is a sea star in the center, its body camouflaged against the grey rocks. The sea star has a rough texture with a mottled pattern of white, brown, and black, blending with the small stones and pebbles around it. To the left, there is a crevice between the rocks, and some greenish-brown sea plants are visible. The water is still, and there are small white specks scattered across the surface, possibly debris or reflections of light. The edges of the rocks are illuminated by sunlight, giving them a warm tone compared to the cooler colors of the water and the sea star.
NPS Photo/D. Orr – Fragile Rainbow Sea Star (Zone 1)
The picture shows a sea star on a rocky surface surrounded by seaweed and marine plants. The sea star is unique with a bumpy texture and its skin is adorned with what looks like a pattern of colorful, iridescent circles, giving it a jeweled appearance. The seaweed varies in color from dark brown to green and red, creating a natural, underwater mosaic.
NPS Photo/D. Wieder – Knobby Sea Star
There is a sea star with a striking appearance, its body covered in what looks like hundreds of bright blue circles with black outlines and a dot in the center, resembling eyes. These circles are set against a dark blue to black background of the sea star’s skin. The sea star is partially hidden under a rocky overhang covered with various marine life, including seaweed, small plants, and other organisms in shades of brown, pink, and purple.
NPS Photo/D. Wieder – Knobby Sea Star
The picture shows a sea star submerged in shallow water on a sandy bottom. The sea star is a rich orange-brown color with a rough texture. To the bottom right of the sea star, there are some vibrant purple and red seaweed or coral-like plants. The water is clear, and the sunlight creates a dappled pattern on the sand through the water's surface. Shadows of the sea star and plants are visible on the sandy bottom, adding depth to the scene.
NPS Photo/D. Wieder – Bat Star

While observing these rock shrimp, VIP Mary had a surprise guest by this Moray Eel. “This moray popped out right next to my hand while I was trying to photograph the striped shrimp. I was not scared, he was just checking me out saying” I’m here! Get a photo!” I do know where there are shrimp this size there is usually a moray nearby.“

The image shows a close-up of a small, red shrimp with intricate white patterns on its body, resting among rocks and marine flora. The rocks are covered with patches of purple and pink algae. The shrimp has long antennae and is positioned facing the camera, giving a clear view of its detailed exoskeleton.
NPS Photo/M. Rose – Red-striped tidepool shrimp. Lysmata California
The picture shows an underwater scene with a focus on a large, dark-colored eel hiding among rocks and marine vegetation. The eel has a smooth, elongated body and its head is visible with a slightly open mouth and a clear, round eye staring towards the viewer. The surrounding rocks vary in size and color, ranging from light beige to dark brown, and are partially covered with what appears to be algae or marine growth.
NPS Photo/M. Rose – Moray Eel

Science Education Coordinator Andrew found this abalone in Zone 2.

Besides man, abalones have a number of predators, including crabs, octopuses, fishes, sea otters, and sea stars. Abalones tend to live wedged in between rocks, held to the substrate by a large muscular foot. Once they have clamped down on the rock, it is impossible to remove them without a pinch bar. Although they tend to stay relatively still, they are capable of movement-especially when being attacked by a sea star.

The picture shows a close-up of a textured, oval-shaped object, which is an abalonel, resting on wet sand. The shell has a series of small, round holes lined up along one edge. The colors on the shell range from dark brown to lighter brown with some white areas, suggesting wear or age.
NPS Photo/P. Geisler – Abalone
The picture shows a close-up of a textured surface, of an abalone, lying on sandy ground. The shell has a rich, dark brown color with streaks of a lighter brown and patches of red and white. The sand surrounding it is a mix of coarse grains and small pebbles in various shades of beige, brown, and some specks of pink. There are also some thin, dark brown seaweed strands scattered around.
NPS Photo/P. Geisler – Abalone
The image shows a sea slug on a sandy seabed. The slug has a soft, elongated body with a creamy beige color. There are some darker markings and speckles on its back, and it has a distinctive darker ring-like marking towards the rear. Its head is rounded with two small tentacle-like protrusions, and the overall texture appears slightly bumpy or granular. The surrounding sand has various small particles and fragments of marine life.
NPS Photo/M. Rose – San Diego Dorid
The picture shows a close-up of a scaly, camouflaged fish clinging to a vertical rock surface underwater. The fish has a mottled pattern of brown, tan, and white, which helps it blend into the surrounding environment. Its fins are spread out, resembling leaves or algae, adding to its camouflage. The rock surface has patches of pinkish-purple coral-like growths on it, which the fish's coloration mimics.
NPS Photo/M. Rose – Fluffy Sculpin, this angle due to the fact that his “walking or perching” like legs are visible.
The picture shows a small crab positioned in the center, resting on a bed of green blades of long thin grass. The crab's body and claws have a reddish-brown color with visible patterns and textures on its shell. The grass provides a contrasting green background that fills the entire image, with some blades crossing over each other creating a sense of depth.
NPS Photo/P. Geisler – Rock Shore Crab
The image shows a green, coral-like plant growing among rocks. The plant has a branching structure with several rounded lobes that resemble the shape of a deer's antlers. The rocks around it have a rough texture and are in shades of brown, beige, and some purple.
NPS Photo/M. Rose – Dead Man’s Fingers
The image shows a vibrant purple sea urchin at the center, nestled among rocks.
NPS Photo/H. Marquez – Urchin
The picture shows a small crab nestled between rocks. The crab has a striking appearance with red and black patterned claws and a greenish-black body. The surrounding rocks are covered with barnacles and bits of seaweed, creating a natural and rugged coastal environment. The crab seems to be in a crevice, possibly seeking shelter or hunting for food. The sunlight is reflecting off the wet surfaces, giving the scene a glistening effect.
NPS Photo/H. Marquez – Rock Shore Crab
The image appears to be taken through a circular lens or microscope, giving it a circular frame. It shows a close-up of barnacles which are oval-shaped objects that have a dark outline and a lighter center, resembling seeds or spores. The background texture is rough and irregular, with a mix of muted colors like beige, brown, and hints of green.
NPS Photo/B. Geyer – Acorn Barnacles
The image is taken through a circular lens or opening, which creates a vignette effect around the edges, making them dark and blurred. Through the lens, you can see a close-up of barnacles, with a focus on the textured surface. The surface has a pattern of colors ranging from dark brown to light tan, with some green vegetation in the background that is out of focus. The overall image has a very narrow depth of field, with only a small portion of the barnacles in sharp focus.
NPS Photo/B. Geyer – Gooseneck Barnacle
The image shows a lobster in a shallow body of water. The lobster is dark in color, with long antennae extending out in front of it. It is surrounded by rocks of various sizes and shapes, some of which are partially submerged in the clear water. The water appears calm, and there is a hint of marine vegetation in the background. The sunlight seems to be reflecting off the water's surface, giving the scene a serene ambiance.
NPS Photo/D. Orr – Lobster at Girabaldi Rock
The picture shows a large slug submerged in clear water with various aquatic plants around it. Sunlight is reflecting off the water's surface, creating a shimmering effect. The plants are green and brown, and some have a reddish hue, adding a touch of color to the scene.
NPS Photo/D. Hunt – Black Sea Hare
The image shows a close-up of a black shiny blob, a sea slug. There are patches of reddish-brown seaweed and small, scattered rocks. A single green strand of seaweed cuts across the scene. The slug is nestled among other stones and pebbles, some of which are visible in the crevices around it.
NPS Photo/D. Wieder – Black Sea Hare
The image shows a close-up of a sand honeycomb-like structure with intricate patterns of small, repeating, hexagonal shapes. The color of the san ranges from light to dark brown, and it appears to be attached to a rock.
NPS Photo/D. Wieder – Sandcastle Worms
The picture shows a sea star tucked away under a rock in a shallow pool of water. The sea star has a mottled appearance with a blend of purples, pinks, and white, especially noticeable on its arms. The rock surface above the sea star is rough and covered with various marine life, including seaweed and small sea creatures. The water around the sea star is clear, reflecting the sunlight, and you can see the sandy bottom of the pool. The overall scene gives a glimpse into the vibrant and hidden life within a tidepool ecosystem.
NPS Photo/B. Geyer – Knobby Sea Star
The image appears to be taken through a circular frame, possibly a telescope or binoculars, giving it a vignette effect with blurred edges. In the center, there's a seagull with white and grey feathers, and yellow beak with a red spot, pecking at the ground. The ground is brown and textured, possibly a wet sand or mudflat, with patches of green seaweed or vegetation scattered around.
NPS Photo/B. Geyer – Gull
The picture shows a cluster of mussels attached to a rock. The mussels have dark, shiny shells with streaks of purple and brown. Among the mussels, there are patches of barnacles with their distinctive volcano-like shapes. The rock is also covered with some green, leafy seaweed, which adds a touch of color contrast to the dark mussels and barnacles. The sunlight seems to be reflecting off the wet surfaces, giving the scene a glistening appearance.
NPS Photo/D. Wieder – Mussels
The picture shows a close-up of a sea slug, nestled among some seaweed. The sea slug has a soft, elongated body with a gradient of colors from a pale yellow at the front, blending into a pinkish hue towards the back, and ending with a hint of purple. Its texture looks slightly bumpy and moist. The surrounding seaweed has a leathery appearance with dark brown tones and some yellowish edges.
NPS Photo/D. Wieder – Yellow Umbrella Slug
The image shows a vibrant pink sea slug, the size of a finger nail. It has numerous slender, elongated tentacles that are tightly clustered together, giving it a lush, full appearance. The slug is situated on a dark, rocky underwater surface, surrounded by various shades of pink and brown marine life.
NPS Photo/D. Wieder – Hopkins Rose Nudibranch
A person on a jet ski is stuck on shallow water.
NPS Photo/P. Raetzman – Jet Skis stuck in Tidepools
The picture shows a close-up of a rocky surface with various textures and colors. There's a small crevice or hole where a crab is partially visible, its reddish-brown shell blending with the surrounding rocks. The area is wet, with patches of seaweed scattered around. The sunlight casts a bright glow on the scene, highlighting the moisture on the seaweed and the rough texture of the rocks.
NPS Photo/D. Orr – Rock Crab (Zone 1)
The image shows a fish submerged in shallow water. The fish has a deep reddish-brown color with lighter beige spots and is resting on a bed of rocks and marine vegetation. The surrounding area is a mix of various shades of purple, green, and brown algae, with some small shells scattered around. The water appears clear, allowing a good view of the fish and the underwater terrain.
NPS Photo/D. Orr – Wooly Sculpin (mini-bathtub)
The image shows a tidepool with clear water, revealing a variety of marine life and vegetation. There are several elements to note: - A large, mottled brown and greenish octopus camouflaged against the rocky bottom - Bright pink algae scattered across the pool - Dark brown seaweed with long, wavy fronds floating near the surface - The shadow of the photographer visible on the water's surface - Sunlight filtering through the water, creating patterns on the creatures and rocks below - Small, indistinct marine animals and plants covering the pool's floor
NPS Photo/S. Kristiansen – Two-Spot Octopus
The image captures a serene sunset at the beach. The sun is low in the sky, casting a warm golden glow across the scene. It's reflected on the water's surface, creating a path of shimmering light that leads to the horizon. The sky is a mix of soft blues and gentle oranges, with wispy clouds adding texture. In the foreground, there's a rocky shoreline with numerous dark stones scattered across the wet sand, partially submerged by the calm sea.
NPS Photo/D. Orr – A great Sunset!

2 thoughts on “What’s in the Tidepools? – December 2023”

  2. Thanks for sending these emails as I really enjoy the photos of what we have in the tide pools. I often share them with my family.

    Besides thanking you for these emails, I would also like offer a bit of editing advice. The photo of the gull refers to it as a “sea gull”. That probably works for a lot of people but I was taught that it is best to not include “sea” when referring to gulls. A simple “gull” should suffice.

    A long time ago I heard a bit of humor on this. Q: What do you call a gull flying over the bay? A: A bay gull.

    Cheers and Happy New Year!

    Larry Sward

    Reply

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