Tomales Bay reflections

 

 

White Gulch in Tomales Bay with Giant Kelp (Macrocystis pyrifera) reflection, 8 August 2025. 

Golden palms

  

Close-up of Sea Palm (Postelsia palmaeformis) blades, 25 June 2025 

Coastal view

  

Black Oystercatcher (Haematopus bachmani) with Sea Palms (Postelsia palmaeformis) in the background, 31 May 2025. 

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):

Micro Macro

  

During a beach walk yesterday (17 August 2024), Eric and I came across quite a few Giant Kelp (Macrocystis pyrifera) juveniles, including this very young individual (above) with a very small holdfast and one single blade. 

Most of these juvenile kelps were a little bit larger, but still early in their development.  Here's an example:

 

 

Below, two images show a closer view of the holdfast and the developing blades.  You can see the blades starting to split and the floats just starting to develop (as small swellings at the base of the blades):

 

 

 

 

 

I appreciated coming across these Giant Kelp juveniles and learning more about how they develop.

P.S.  I'm including one more photo just for fun.  The floats are little larger in this individual, and I hadn't noticed at the time, but you can see my reflection in the floats.  A self-portrait in kelp!

 

 

 

P.P.S.  Regarding the title of this post — In casual conversation, we sometimes shorten the scientific name of Giant Kelp, Macrocystis, to "Macro."  And because I am highlighting small individuals in this post, I thought it would be fun to play on those two names = Micro (small) Macro (Macrocystis).

Kelp toes

  

Tiny little kelp toes -- close-up of a Bull Kelp (Nereocystis luetkeana) holdfast attached to a rock.  Washed ashore in Bodega Bay on 27 July 2024.

Blending in

  

Well, I need to take a better photo, but here's a quick one for the record.  This looks like Corambe pacifica, a nudibranch I haven't photographed yet.  It was on a bryozoan colony on a piece of drift kelp.

Along with Corambe steinbergae, this species is a bryozoan specialist. Its coloration and patterning looks just like the bryozoan prey.

For an introduction to these intriguing nudibranchs, see "Ay, Corambe!" on 20 September 2013 and "A story with a point" on 17 August 2014 (this one includes a link to a great video!).

A local network?

  

Net-of-Cords Kelp (Dictyoneurum californicum) 

Note the interesting reticulated or network-like patterning.  The blade was in the process of splitting into two through the center.

Dictyoneurum has a distinctive holdfast -- strap-shaped, with haptera (branching root-like structures) on both sides.

 

 

[This kelp had washed ashore, so I placed it on a rock to take a photo, but this kelp lives much lower in the intertidal zone.]

Summer gold

  

Close-up of Giant Kelp (Macrocystis pyrifera) in Bodega Harbor on 29 June 2024.

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 perfect fit

  

I like the warm colors in this photo, so it seemed like a good opportunity to introduce Lottia instabilis.  

This interesting limpet is stenotopic — meaning that it lives in a narrow range of conditions or a restricted habitat.  Lottia instabilis lives on kelps, especially on the stipes (or stems).  In the Bodega Bay area I've seen it on Walking Kelp (Pterygophora californica).  I don't have a great photo of this species on kelp, but here's one from 2012 so you can visualize where it lives:

One of the unusual things about Lottia instabilis is the shape of the bottom edge of the shell.  To fit tightly against the kelp stipe, which is rounded, the shell is curved upward at both ends:

 

 

So the shell is "unstable" (or rocks back and forth) if you place it on a flat, horizontal surface (hence the "instabilis" species name).  But if the limpet is on a rounded kelp stipe, it fits perfectly!

A bigger anchor

 

 

I was leading a walk about seaweeds today and we encountered a few of these Bull Kelp (Nereocystis luetkeana) holdfasts attached to small rocks.  The rocks likely served as anchors when the kelp was small, but once they grew larger these rocks just weren't heavy enough to keep the kelp in place.

 

 

 

Fun to see the little kelp "feet," but maybe next time the microscopic stage of the kelp will find a larger rock.  You know the famous quote, "You're gonna need a bigger boat anchor."  ;)

Before the split

  

Always fun to see juvenile Bull Kelp (Nereocystis luetkeana).  This one was photographed a few days ago on 12 August 2023.  The blades haven't quite split apart yet, but you can see where that will happen.

Golden grooves

 

 

Close-up of Sea Palm (Postelsia palmaeformis) blades, 10 June 2023.

 

Impressionism in the sea, Part 2

  

Some of you might remember that I shared a similar photo back in 2013.  For Earth Day, here's Impressionism in the sea, Part 2!  

Enjoy the Earth today and every day!

Kelp in snow?

  

Bull Kelp in foam...looking a bit like snow!

Photographed from Bodega Head on 18 October 2022.

Floats and blades

  

I'm getting ready to talk with some students about local kelps, so here's a photo of Bull Kelp (Nereocystis luetkeana) from June 2022.

A chance meeting

  

Eric spotted this Bull Kelp (Nereocystis luetkeana) holdfast washed up on the beach recently.  The holdfast was still attached to a sizable piece of rock.  And it was interesting to see both Giant Barnacles (Balanus nubilus) — the large white barnacles in the center of the image — and pelagic gooseneck barnacles (Lepas sp.) — the small grayish clusters of barnacles along the left edge of the image.  

Giant Barnacles can be found in the low intertidal zone and subtidally, but pelagic barnacles are generally found offshore in the open ocean.  I'm not sure how often these two species of barnacles are found growing in the same place.  And seeing Lepas on this holdfast means the kelp and the rock it was attached to have been floating around offshore for a while before washing ashore.

3 for 3,000

Whew, well it's hard to believe, but this is post #3000!  (3000 posts over 10.5 years.)  So here's a little video clip to mark the occasion.

This is an older video (from 2018), but I've wanted to share it for a while.  It shows a River Otter family (a mother and three pups) on a morning outing — waking up from a nap, using a communal latrine, sliding down some Feather Boa kelp into the water, swimming along the shoreline together.  And it includes audio!  I've written about otter calls before — the pups use a high-pitched bird-like chirp to keep in touch with the rest of the family.

On this day I was working quietly in the low intertidal zone when I noticed this otter family swimming by.  They swam past me, climbed up onto the seaweed-covered rocks, and curled up for a nap!  I didn't want to disturb them, so I kept working and watched for activity out of the corner of my eye.  Eventually they woke up and that's when this video clip starts. 

I didn't know the otters were going to make their way back towards where I was working.  You'll see that eventually they notice me.  One of the pups makes sure the others know about me, too, and then they continue along the shoreline.

I hope you enjoy this little window into the life of River Otters.  Thanks so much for checking into the Natural History of Bodega Head blog.  Knowing you're out there inspires me to keep learning and to keep sharing.  Who knows how far beyond #3000 we'll go!

 

 

P.S.  Many thanks to Eric for helping to edit this video, and for participating in so many NHBH blog posts!

At the surface

  

A nice patch of Bull Kelp (Nereocystis luetkeana) close to shore, 16 June 2022