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!

End of a long odyssey

For Eric’s summer class, we used a small plankton net to collect some plankton near the mouth of Bodega Harbor during a flooding tide last week.  The students sorted through the plankton sample in lab to see what larval forms they could find.  One of the students (Zack) spotted an amazing larval form.

This is a brachiolaria, a late-stage larva of a seastar, that appears to be the Ochre Seastar (Pisaster ochraceus).  The photo above was taken under the microscope, but the specimen is quite large for a planktonic larval stage, close to 2 mm long and visible with the naked eye. This larval form is beautiful and alien in appearance and doesn't look much like an adult seastar!   

A surprising feature of the brachiolaria larva is that the juvenile seastar begins developing within the transparent larval body.  In the photo above, the juvenile body is visible near the bottom of the larva and is shiny white in color.  With a closer view, you can see that the developing juvenile body already includes the start of calcareous ossicles that will become the internal skeleton of the juvenile and adult seastar!  In the photo below, the developing ossicles look like intricate snowflakes (white arrow).

 

This brachiolaria appeared to be nearing the completion of its planktonic larval phase, which can be a long odyssey in seastars.  Under laboratory conditions, the planktonic phase has been reported to last from ~40 to 228 days in Pisaster ochraceus, depending on temperature and food.  Pisaster spawns in the spring in California, so this larva likely spent at least several months at sea before entering Bodega Harbor.

When the brachiolaria returns to a rocky shore and finds suitable habitat, it will initially attach to the rock with a short stalk.  Remarkably, the transparent larval body is reabsorbed into the juvenile body during a dramatic metamorphosis. Soon after settlement, the juvenile sea star breaks off its stalk and crawls away as a tiny sea star. 

The larval phases of a sea star.  Illustrations compiled and modified from various sources.

Eric was able to capture some video under the microscope of this beautiful sea star larva.  In the video, notice the long ciliated larval arms used for swimming and gathering food from the plankton. You will also see a close-up of the developing juvenile body (white in color) and the snowflake-like ossicles.  (If you can't see the video player below in the e-mail message, click here to go directly to the video.)

With many thanks to Zack for spotting this planktonic wanderer!  And to Eric for his microscope camera skills and the helpful diagram.

P.S.  For more information about development in sea stars, see earlier posts on the larvae of the Bat Star (Patiria miniata) — "A new star(t)" in 2013 and "A profound change" in 2023.

P.P.S.  As a reminder, when juvenile Pisaster are first visible to human eyes in rocky shore areas, it's about 4-6 months after metamorphosis.  Here's an example of one that's about 4.5 mm across (between ¹/₈ inch and ³/₁₆ inch), photographed in November 2014.

 

Sea star art

  

Close-up of the upper surface of a Bat Star (Patiria miniata).  Those are papulae (in purple) among clusters of spines (in pink).  (Papulae are finger-like projections for gas exchange). 

A festive fourth

  

Red Sea Urchin (Mesocentrotus franciscanus) from Mendocino County in late May 2026.

 Happy Fourth of July! 

Love for the oceans

  

Seemed like this photo could be appropriate for World Oceans Day (8 June 2026).  

A heart from and for the ocean!

Here's the entire animal:

 

The heart shape surprised us, as the central opening on the underside of a sand dollar is usually circular.  But this skeleton broke in just the right way to create a perfect heart.  Pacific Sand Dollar (Dendraster excentricus) photographed in Marin County on 22 May 2026.

Sharing our thanks and love for all of the Earth's oceans. 

Rock star?

  

Whew, we were busy with field work during the low tides this past week, but we managed to take a few photos on the side.  

Here's one that Eric took in Mendocino County today (23 May 2026) -- a beautiful Daisy Brittlestar (Ophiopholis kennerlyi) on the underside of a rock with clusters of small tubeworms. 

Peeking out

  

A beautiful view of the tentacles of an Orange Sea Cucumber (Cucumaria miniata).  You can also see a few of the cucumber's tubefeet closer to the rock.  Photo from Del Norte County in California on 4 April 2026.

With thanks to Eric for a great photo! 

September star

  

Nice view of a Forbes' Sea Star (Asterias forbesi) in a shallow tidepool in Scituate, Massachusetts, on 20 September 2025.

Eric was able to zoom in for an amazing closeup, too:

 

 

Visible above are short white calcareous spines, the orange madreporite (sometimes called a sieve plate, which is an opening to the water vascular system), and the transparent papulae (finger-like projections involved in gas exchange).  

Thanks for the great photos, Eric!
 

Blue background

  

Last week I came across an Ochre Sea Star (Pisaster ochraceus) that was noticeably blue.  It's a little hard to tell from the photo above, but hopefully you can see the blueish background coloration among the clusters of white spines.

We've been monitoring Pisaster for over a decade and have observed thousands of individuals during that time, but I can't recall seeing a blue adult sea star until now.  The most common colors are orange, brown, and purple, but this blue individual seemed unusual, so I took a quick photo for the record.

That said, we often see juveniles with blueish coloration — see photos below from this past winter:

 

 

 

I've often wondered if the blue juveniles gradually turn purple, and perhaps some do, but the blue adult in the first photo shows that sometimes the adults can be blue, too! 

Little one

  

A tiny Six-armed Sea Star (Leptasterias sp.) photographed in Mendocino County on 31 May 2025.  This juvenile sea star was only ~3-4 mm across from arm tip to arm tip.  

If you look carefully, you can see some of its tube feet extending away from its arms.  And the small red eye spots at the tips of the three arms in the foreground are also visible. 

Rather than releasing eggs into the water column, Leptasterias broods its embryos and the young sea stars crawl away from the adult.  Back in 2012, I shared photos of an adult Leptasterias with its brood of embryos and an image of an adult with many juveniles in the surrounding area (it's likely the juveniles recently crawled away from the adult).  To review those photos, check out the post called "Four brooders in one" on 29 February 2012.

P.S.  Thanks for the great photo, Eric! 

Upcoming

  

For all of the marine invertebrate enthusiasts out there — I wanted to mention that Eric will be presenting a webinar for Bay Nature magazine this week on Wednesday, Feb. 5, from 12-1 p.m. PST.  He'll be discussing the local diversity of marine invertebrates and some new discoveries, accompanied by lots of great photos and videos!

If you're interested in checking it out, you can register to join the talk online here.

P.S.  This is a Dwarf Brittle Star (Amphipholis squamata) photographed on Bodega Head last week.

Glass-spined

  

Glass-spined Brittle Star (Ophiothrix spiculata) photographed in Bodega Bay on 27 January 2025.

Twinkle, twinkle

  

Juvenile Short-spined Sea Star (Pisaster brevispinus) photographed in late December 2024.  This individual was only ~20 mm across (arm tip to arm tip).

Time for owls

  

Some of you might remember that I sometimes see owls in pieces of sea urchin test.  Here's one perched on a branch of coralline algae.  :)  From 8 June 2024.  Do you see an owl, too?

P.S.  For more "urchin owls," see the post called "Duetting" on 11 March 2013.

New Year's Eve ball drop?

  

Very young Red Sea Urchin (Mesocentrotus franciscanus), about 8 mm across, on 31 December 2024.  Best wishes for 2025!

Winter star

  

Juvenile Ochre Sea Star (Pisaster ochraceus), about 6 mm across, on 30 December 2024

A hint of orange

  

An interesting find today (27 June 2024) -- Pachythyone rubra, a more southern sea cucumber that's more common south of Monterey.  It's been documented in Bodega Bay previously, but only a couple of times.  Note that hints of orange color at either end of the cucumber, and the tubefeet that are scattered across the body rather than in regular rows.

To learn more about Pachythyone rubra, check out the previous post called "Goodbye, Rubra Tuesday" on 5 March 2018.

P.S.  If you happen to come across this species in Sonoma County or farther north, I'd love to hear about it.

18!

  

Okay, how many arms on the Six-armed Sea Star above? 

And how many arms on this greenish Six-armed Sea Star? 

And how many arms on this Six-armed Sea Star that's having a tube foot party?

Add then all together -- how many arms total on all three of these Six-armed Sea Stars?

Yes!  18!  (Okay, most of you know I'm a Boston sports fan...and I can't help but post a big congratulations to the Boston Celtics for winning the 2024 Championship and their 18th Championship Banner!  That was an amazing season, Celtics!  Woohoo!)

Role model?

  

Two Henricia pumila sea stars in a shallow pool in the low intertidal zone.  The one on the left is likely older than the one on the right, but growth rates in juvenile sea stars are highly variable, so it's hard to say for sure without knowing more about these individuals.  Photographed in Mendocino County on 9 June 2024.

Pool of light

  

 Morning light in a tidepool with sea urchins (purple) and sea anemones (green).