Tidepooling at 66° North

During our first few days in Iceland, we were fortunate to find some excellent tidepooling locations.  We've been taking lots of photographs, but it's hard to find time at the end of the day to write a complete post , so I'm sharing a few fun highlights for now.

 

 

Silver-spotted Anemone (Aulactinia stella)

 

 

 

 

Northern Red Chiton (Boreochiton ruber) 

 

 

 

  

A small staurozoan (Haliclystis sp.).  This stalked jellyfish was very active so the image is a little blurry, but we were excited to find a couple of them! 

 

 

 

  

A striking Daisy Brittle Star (Ophiopholis aculeata).  We found quite a few individuals all with different color patterns.

 

We've been impressed with the diversity of marine invertebrates in the tidepools in Iceland and feel fortunate to be exploring and learning more about them.  We hope you enjoy meeting them, too!

Flecktones?

  

A nice little chiton for you — a juvenile Lepidozona radians.

Photographed in the low intertidal zone on 29 June 2025.
 

A hat trick?

  

We were focused on other species while doing surveys along the coast in Mendocino County last weekend, but along the way Eric spotted several nice chitons.  Above, meet Tripoplax regularis.  (Also refer to the post called "The original sequins" on 26 February 2017.)

Below, this looks like a species of Mopalia, but we're not sure which one.  We wondered about Mopalia imporcata, a species we're not familiar with.  If anyone has thoughts about the identity of this chiton, we'd be interested!

 

 

 

And, one that was fun for us —  a juvenile Katharina tunicata.  This individual was only ~1.5-2 cm long.  Katharina has become less common in the Bodega Bay area, so it's encouraging to see a young one starting out:

 

 

 

A wonderful trio, Eric!

Holding fast?

 

 

We were doing surveys during the low tide this morning (27 April 2024) when Eric spotted this unusual interaction.  The holdfast of a small Sea Palm (Postelsia palmaeformis) had grown over and appeared to be attached to a chiton, Nuttallina californica!

 

Chitons are mobile grazers, moving over the surface of the rock and feeding on algae.  Perhaps they take breaks and stay in place for a while, which allowed the kelp to attach to it?

 

We didn't actually pull on the chiton to see if the haptera (root-like outgrowths) were definitely attached to the chiton, but it sure looks like it:

 

 

 

We'll be back in this area and can check on the kelp and chiton again to see how things turn out.

A chiton with flair

  

Eric snapped this great photo of a Veiled Chiton (Placiphorella velata) during field work this afternoon (8 March 2024).  Impressive how well this species looks like the surrounding habitat — rock, coralline algae, and red seaweeds.  This individual even has a little bit of branching coralline algae growing on its shell plates!  

Here's another image from a little farther back:

 

 

For more information about this intriguing predatory chiton, you can review the post called "A veiled threat" from 21 August 2012.  And there's a beautiful underwater photo in the post called "Camouflaged like coralline" on 11 August 2021.

Disappearing act

  

One of the most impressive features of many animals in the intertidal zone is the way their color patterns match their surroundings.  It makes it challenging for visual predators to spot them.  And it also requires an observer to slow down and let their eyes and mind adjust to the setting in the tidepool.  (Maybe we need a new phrase ="slow tidepooling"?)

We thought it would be fun to show some examples.  Above is a chiton (perhaps Lepidozona radians) — note there are eight plates, but the middle four plates are orange, the front two plates near (head end) are flecked with brown and green, and the back two plates (tail end) are mottled.  These varied colors make it hard to identify this as a chiton at first.

Below is a small sculpin.  Check out the way the pink stripe running across its body matches the coralline algae patches on the rock.  And the other colors look like the surrounding rocks (grays and greens) and encrusting algae (deep maroon).  It also helps that sculpins often stay very still — the lack of movement makes it less likely that they'll catch your eye:

 

 

The camouflage abilities of octopus are well known — they can settle on a new substrate and blend in within seconds by adjusting pigment cells (chromatophores) in their skin.  Here's one looking a lot like a rock — but also note how well the arms/tentacles on either side of the body have a different color and pattern than the main portion of the body.  It's hard to make them out!  (If you look closely sometimes you can spot the suckers on the underside of the tentacles.)

 

 

And here's one more — an intriguing shrimp called a Deep-blade Shrimp (Spirontocaris prionota). (Hint: Look for the shrimp's eyes in the center of the photo.)  Not only do the colors of the shrimp match the coralline algae, but the shrimp also has small hairs (setae) that accumulate bits of debris that help it look "messy", making it less clear that this is a shrimp.

 

 

It takes some special attention to spot animals like this when they're so well camouflaged, but it's worth the extra time! 

ADDENDUM (31 December 2022) — P.S.  To make it easier to find the octopus, here's an edited photo showing the outline and main features:

 

 

Plates of salmon

  

Eight plates for 8/8!

This is a large chiton photographed at Point Arena on 3 June 2022.  I think it's a species of Stenoplax (perhaps S. heathiana?), but I haven't seen this group of chitons that often.  I loved the salmon color of the plates!

Camouflaged like coralline

Eric took this beautiful photo of a Veiled Chiton (Placiphorella velata) found with his class today (11 August 2021):

I love the pink and white striping...the color matches the crustose coralline algae growing on the rock.  And note that the chiton's plates are festooned with small tubeworms (white or gray calcareous tubes with bright orange tentacles).

For more information about this carnivorous (!) chiton, check out this earlier post from 21 August 2012. 

P.S.  Thanks for sharing, Eric and summer students!

White with maroon accents + update about blog e-mails

  

A very nice chiton called Lepidozona radians.  This species is known for being highly variable in color.  Most of the individuals we've found in Sonoma County have been more brownish overall, with radiating flecks on the plates (see note below).  But during a recent low tide we came across several individuals with this white and maroon combination.  Interesting!  

P.S.  For a look at a different color form, check out the post called "The original sequins" on 26 February 2017.

P.P.S.  I've been informed that the service for sending out e-mails with NHBH blog posts will no longer be offered starting this month.  I'll be looking into a new one, and I hope I can transfer everyone over to a new service, but if not, watch for a note here (on the NHBH website) with a new way to subscribe to receive blog posts via e-mail.  Sorry about this!  I'm not that savvy about these types of things, but I'll be working on a solution.

Local diversity

  

Eric noticed a beautiful scene in the low intertidal zone a few days ago.  There are six (!) different phyla (major animal groups) represented in this image, all in an area that was only ~4 cm x 4 cm (or ~1.5" x 1.5").  

Feel free to look around and see what you can find.

In the next image, I've circled or pointed to representatives of each phylum.

 

 

Green arrow = sea anemone (Epiactis handi), Phylum Cnidaria
White circle = barnacle (Chthamalus dalli), Phylum Arthropoda
Blue circles = flatworms (unidentified), Phylum Platyhelminthes
Orange arrow = peanut worm (Themiste pyroides), Phylum Sipuncula
Purple oval = tubeworm tentacles (Phragmatopoma californica), Phylum Annelida
Pink arrow = chiton (Tonicella lokii), Phylum Mollusca

A van Gogh or a galaxy?

 

 

A close-up of the girdle or margin of a Woody Chiton (Mopalia lignosa), photographed on 12 June 2021.  In the field, Eric noticed the amazing colors and patterns, especially the different shades of blue.  It reminded him of a celestial sky in a van Gogh painting, while it made me think of looking out at a galaxy:

 

Here's the entire animal on a boulder in the low intertidal zone.  [You can click on the images for larger versions.]

 

 

Red end of the spectrum

There's a lot of red in the intertidal zone, along with pinks and oranges and golds at that end of the color spectrum.  Sometimes it's fun to scan across different species to see the color similarities.  Here's a little tour from a recent outing:

 

 Fish eggs

Aldisa sanguinea (nudibranch)

 

Peanut worm (Themiste sp.) tentacles

Clam siphons

 

 

Veiled Chiton (Placiphorella velata) in hunting position

 

Juvenile Red Sea Urchin (Mesocentrotus franciscanus)

Beads and bristles

Several days ago, Eric found this handsome chiton under an intertidal rock in the Bodega Bay area.  He recognized that it looked different than the chiton species that we usually encounter, so he took a few photos for the record:

 

Notice the attractive beaded ribs on its eight plates and the impressive setae (stiff bristles) around its margin:

 

 

Meet Mopalia porifera!  This is the first time that we have seen this species.  It can be distinguished from other chitons in the genus Mopalia in part by the three rows of alternating, sparse setae, which are especially prominent at the spaces where the plates meet.  This individual was 20mm long.

Mopalia porifera is primarily a southern species found from Baja California, Mexico, to central California.  We are aware of only a handful of records of this species from north of Point Reyes (museum specimens all collected at Dillon Beach in 1947 or 1974).  

Because this chiton might be rare in this area, we returned to the site to look for the chiton again (for more photos) and to see if there were other individuals. 

After a little searching, Eric was able to relocate the chiton.  Although it had shifted its position, it was on the same rock.  The shell sculpturing is quite striking:

 

 

We were also able to find a few more individuals.  They were smaller than the first chiton, and slightly different colors, but you could see the same beaded sculpturing on the plates and the prominent bristles along the margins:

 

 

It was wonderful to see a new species of chiton!  Kudos to Eric for spotting it and recognizing that it looked different, and many thanks to Anthony for confirming this species identification.

The tail end

When we were conducting a survey in late June, Eric spotted an unusual chiton.  I realized it was a species I hadn't seen before, but it was still familiar because it reminded me of a photo I'd seen in a book.  (That's one of the values of browsing through field guides and other natural history books — it helps you recognize something in the field, even if you've never seen it before.)

We were looking for something else, so we had to continue our surveys, but I took a few quick photos for the record.

 

Chitons have eight plates across their dorsal surface, including a head plate (on the left in the photo above) and a tail plate (on the right).  This species is unusual in that the tail plate is higher than all of the other plates, so it looks like a bump or protrusion at the back end.  I didn't capture this feature very well, but here's another view.  If you scan across all of the plates, you can see how the tail plate (on the right) is raised and rounded:

 

In the next image, you can see the sculpturing on the head plate (on the left).  It has 10 nice radiating riblets with little rounded bumps on top.  [Also note that each of the middle plates has two radiating riblets (also with little bumps) on each side.]

 

Meet Callistochiton palmulatus!  It's the first time we've observed this chiton species.  We're still learning about them, but in general it sounds like they're more common in the southern part of their range.  We are aware of one record from Mendocino County in 1946, but otherwise the observations we've found are from south of San Francisco.

One more view of this intriguing chiton walking away towards the other side of the rock:

 

Zigs and zags

I've been working on some photo organization today (long overdue!).  Here are two beautiful chitons that I haven't had a chance to share yet:

 

 

These chitons were photographed in the low rocky intertidal zone on 22 January 2019.  They both appear to be in the genus Mopalia, but I'm not sure which species yet.  (If you have any ideas, let me know!)

Waiting

Before I took this picture last month, I hadn't realized how much a chiton could look like a sea anemone!

 

The chiton (in the center of the photo) is a Veiled Chiton (Placiphorella velata).  It might be difficult to spot at first, but it's nestled next to an Aggregating Anemone (Anthopleura elegantissima). 

Below is a side view of the chiton where can see how the setae (bristles) at the head end look similar to the tentacles of the anemone:

 

Placiphorella is an unusual chiton.  While most chitons are grazers, this species is predatory.  It raises its veil (as in the photo below), waits for prey to pass underneath, and then clamps down quickly to capture it.  The bristles above probably help to camouflage the chiton, making it harder for prey to recognize a possible predator.

 

I first introduced Veiled Chitons back in 2012 (was it really that long ago?).  If you'd like to learn more about them, check out the post called "A veiled threat" from 21 August 2012. 

 

All together now

I had to do some intertidal field work this afternoon (18 February 2019).  When I finished, I looked around a bit.  I was starting to focus on this chiton (Lepidozona cooperi), when I noticed something intriguing next to it:

 

My first thought was that the striped object might be the arm of a brittle star.  But when I was able to see it more clearly, I realized it was a polychaete worm.  

I think we've seen this worm before — for example, see the post called "Ruler worm?" from 1 May 2013.  However, this individual appears to be broader.  When I zoomed in, I could see that it's possible she has lots of cream-colored eggs inside?

 

I'll have to ask around for some help with the identity of this intriguing worm.

P.S.  In case you're wondering, the white spiraled animal at the head end (left side) of the worm is a foram (Foraminifera).  The bright pink animal in the same location is a bryozoan (Eurystomella bilabiata).  The paler pink in the lower left corner of the second photo (and above and to the right of the chiton in the first photo) is coralline algae.

High and low

 

Today's tides were some of the highest and lowest of the year.  

Above, a flock of Snowy Egrets (Egretta thula) concentrated on a small patch of salt marsh remaining above the high tide (+6.9 feet) in Bodega Harbor this morning.

 

 

And a small juvenile Gumboot Chiton (Cryptochiton stelleri) exposed during the low tide (-1.4 feet) on the outer coast in the early evening.