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.

 

New to the north?

  

Abby wrote to let us know she had observed an unusual flatworm on 17 June 2026.  Amazingly, we encountered what looks like the same species in a different location on 20 June 2026.  Both were found along the rocky shore in the low intertidal zone.

We think this is Stylochus franciscanus, although it's a new species for us, so we're open to feedback.

There are two flatworm species that apparently look similar but differ in subtle ways.  For example, Stylochus franciscanus has marginal eyes that only extend ~1/4 of the way along the perimeter of the body, while Stylochus californicus has marginal eyes that extend along the entire perimeter.  And the tentacles of Stylochus franciscanus are closer to the anterior margin vs. farther from the margin in Stylochus californicus.  See illustrations below (modified from Libbie Hyman's 1953 account of flatworms in California -- see a photo of Libbie in this post):

 

 

 

Because both of these flatworms are unusual in northern California, we documented this individual with a microscope video (below).

 

In the video clip, watch for several features: 

- an overall pattern of lighter and darker brown spots

- at 18-20 seconds, you can see the marginal eyes (tiny black dots) along the margins, but only at the anterior/head end

- at ~30 seconds, note the pair of transparent nuchal tentacles that are relatively close to the anterior margin

- at ~38-40 seconds, a head-on view shows the clusters of cerebral eyes (black dots) *within* the nuchal tentacles (!)

 

 

Stylochus franciscanus records primarily come from San Francisco Bay and the central and southern California coasts.  From what we can tell so far, these are the first records north of San Francisco (although we need to do additional research to confirm the distribution records).  

 

With many thanks to Abby for alerting us to the presence of this species in Marin County and to Eric for capturing and editing the video footage. 

P.S.  If you can't see the video player in the e-mail message, click on the title of the blog post to go to the NHBH website to see the video.

P.P.S.  Fun fact -- "franciscanus" in the species name likely refers to San Francisco Bay, as the first specimens used to describe the species were collected from locations within the Bay.

P.P.P.S.  If you happen to see this flatworm north of Bodega Bay, we'd love to hear about it/see photos!

P.P.P.P.S.  Happy summer!  :) 

Golden-edged and fine-lined

  

It's hard to believe that this striking flatworm remains undescribed.  Abby noticed it in the low intertidal zone last week and Eric was able to get some video for documentation (see video clip below).

This flatworm is listed in the Intertidal Invertebrates of California (Morris, Abbott, and Haderlie 1980) as Eurylepta sp.  They didn't include an actual photo, but instead represented this species with a painting.  The colors are a little different, but I think you'll see the resemblance:

 

Modified slightly from Morris, Abbott, and Haderlie (1980) 

 

There have been more recent discussions regarding whether this flatworm is in the genus Prostheceraeous, but at this time we can't locate a reference to cite for that, so we'll just say that it's in the Euryleptidae family.

 

There are only a few records of this species in Marin County, and none that we know of north of there.  Most observations are in the Monterey area and farther south. 

 

If you happen to see one, we'd love to see photos and to hear about other records. 

 

And now for the video!  Eric put together a few clips so you can appreciate the color pattern and the flowing movements of this flatworm.  [If you're reading this in an e-mail, click on the title of the post above to go directly to the NHBH website to see the video player.]

 

 

 

With many thanks to Abby for sharing her observation and to Eric for creating the video!

Tripping the light fantastic

  

During a walk at Dillon Beach on 27 December 2025, we came across several large masses of egg capsules.

Here's a photo in Eric's hand for scale: 

 

 

These are egg capsules of the Opalescent Inshore Squid (Doryteuthis opalescens).  When you look at the capsules up close, if the embryos are far enough along in their development, you can see tiny squid inside.  Look especially for the two large eyes.  Each compartment holds one squid (so an individual egg capsule can hold 50 or more developing embryos):

 

 

 

Development time is dependent on water temperature, but it can take 6-10 weeks for the little squid to hatch out in cooler temperatures. 

 

One of the egg capsules (above) appeared to have mature squid larvae that looked like they'd be ready to hatch soon.  We put the capsule into a large ziploc bag with seawater and what do you know, about an hour later, tiny (~3 mm long) squid larvae had emerged from the capsule and were swimming around.

 

Eric was able to capture some amazing video of the squid larvae and their beautiful chromatophores under a microscope (see below).  [If you can't see the video player in your e-mail, click on the title of this post above to go directly to the NHBH website to watch the video.]  It's fascinating to see the pulsing chromatophores in action.

 

We thought you might enjoy a little light show to ring in the New Year!

 

Best wishes for 2026! 

 

P.S.  For more information about how chromatophores work in squid and octopus, check out this "Hide and seek" video that Eric made in 2021.

 

Starting the journey

  

Sharing another terrapin photo and a short video clip (below).

In the photo above you can see this hatchling's egg tooth.  If you look closely at the very tip of the snout, you can see a pale sharp point.  The egg tooth helps the hatchling break out of the shell.  Later the egg tooth will fall off.

We also have a short video clip of the turtle as it starts on its journey from the nesting area to the salt marsh.  You'll see the turtle blinking, breathing, looking around, and pushing through the sand.  [If you can't see a video player in the e-mail message, click on the title of the post to go to the NHBH website.]

Good luck, little one!

P.S.  With thanks to Eric for editing the video clip! 

Waving hello

Christian spotted this beautiful nudibranch in Bodega Harbor last week, and Eric was able to capture some nice video footage, so here you go… 

…meet Dendronotus iris!

Below is a short clip of this juvenile Dendronotus iris in action.  It was only ~1 cm long, so this footage was taken with a microscope.  [If you can’t see the video player in an e-mail, just click on the title of the post to go to the NHBH website.]

The rhinophores (sense organs at the front) are so tall it made me think of antlers!  And you’ll probably be intrigued that the nudibranch is transparent, so you can see the orange-colored branches of the digestive gland extending into the cerata (tall extensions on the nudibranch’s back):

 

With many thanks to Christian and Eric for the great find and fun video!

 

Sheaves of gills?

  

From the "Little wonder" post from ~1 week ago, I think you can tell that we've been looking closely at a couple of nudibranchs that live on the patches of bryozoan found on Giant Kelp (Macrocystis pyrifera).  Above, Eric is scanning the bryozoan colonies for signs of the nudibranchs.

We've found both Corambe pacifica and Corambe steinbergae, but these nudibranchs are small (often under 1 cm long), so it can be difficult to tell which species you're looking at. 

To make it a little easier for other folks to know what to look for when identifying these two species, Eric put together a series of video clips highlighting the differences between them (see the video below!).

In the video, first you'll see the bryozoans that the nudibranchs feed on.  The zooids emerge and extend their tentacles to feed.  When the nudibranchs appear, watch for these features:

Corambe steinbergae:
- the edge of the nudibranch is smooth around the entire perimeter
- the rhinophores are simple (no extra "decorations")
- there is a gap between the two rows of gill plumes on either side of the midline (and the gill plumes look a little more linear)

Corambe pacifica:
- the edge of nudibranch has a deep notch at the posterior end
- the rhinophores are sculptured or fluted
- instead of a gap between the two rows of gill plumes, in the center there are several gill plumes that are pinnate = with short branches aligned on either side of the main stem (they look a bit like feathers)

For reference, it also might help to see how the gills plumes of these two species were illustrated in the original descriptions:

 

Above, Corambe pacifica — the entire animal with posterior notch; a close-up of a fluted rhinophore; a close-up of the gill plumes from below (drawings by Olive Hornbrook MacFarland).

Above, Corambe steinbergae — the entire animal without a posterior notch; showing the simple rhinophores; and illustrating the gill plumes with a gap between the two rows.

One thing I didn't mention yet is that the gill position of these two species is unusual.  Many nudibranchs have gills (or other respiratory structures) on the upper surface.  In this case, the gill plumes are positioned on the underside!  But luckily Eric was able to film the nudibranchs from above and below, so this is an excellent view of the gills and the differences between the two species.

Check it out!  [And if you can't see the video player in an e-mail, just click on the title of the post to watch it on the NHBH website.]

Nicely done, Eric!  The best views of the differences between Corambe steinbergae and Corambe pacifica captured on film!

P.S.  Corambe pacifica's pinnate gill plumes have an interesting shape.  When viewing them I kept thinking about a Henri Matisse cut-out called The Sheaf (La Gerbe):

Little wonder

  

Camouflage week continues!

You might recall that back on 14 July 2024, I introduced this amazing nudibranch, Corambe pacifica.  I also mentioned that I needed to get a better photo.  Well, here you go!  And, lucky us...Eric was also able to record some beautiful video clips.

Things to look for: 

- how well the color and patterning of the nudibranch match the bryozoan in the background

- two rhinophores (sense organs) near the leading edge (viewed from above, they look like a pair of white spots)

- a small notch along the back edge of the nudibranch

- when viewed up close, sometimes you can catch a glimpse of the branched gills inside the notch (more about the gills in a future post!)

Here's the video clip (below).  [If you can't see the video player in the e-mail message, just click on the title of the post above to go directly to the NHBH web page.]

Stay tuned for more about Corambe pacifica.

And thanks to Eric for the great video!

Barrel bubble

  

Caroline spotted this intriguing gastropod in Tomales Bay on 7 August 2024.  It's a species we hadn't seen before, so Eric took some documentary photos and videos (see the wonderful video below!).

Although we need to confirm with experts, we think this is a barrel-bubble snail, Acteocina inculta.  This is generally described as a southern species, from either Monterey Bay or Morro Bay southward.  There are a couple of museum records for San Francisco, but it's possible this is the first record for Marin County — we'll need to do more research on museum records.

Acteocina inculta is a small head-shield slug (this individual's shell was a little over 3 mm long).  Note the head-shield in front of the shell — and that the back edge of the head-shield is split into two rounded lobes.

Eric captured some very nice video footage of this hard-to-find species, so here you go!  

[If you can't see the video player in the e-mail message, click on the title of post above to go directly to the NHBH website.]

With many thanks to Caroline for her sharp eyes and hard work!