Homes on the rocks

  

Northern Acorn Barnacles (Semibalanus balanoides), photographed in Scituate, Massachusetts, on 9 December 2024.

Thanks for the great photo, Eric!

Nestled among the branchlets

 

 

We looked down to see this interesting seaweed on the beach today — Cumagloia andersonii.  It usually doesn't have little white specks on it, so we took a closer look.  Below you can see a hint of what's attached to it:

 

 

These are juvenile pelagic gooseneck barnacles (Lepas sp.).  That means it's likely the seaweed has been drifting offshore for a while (long enough for planktonic barnacles to find it, settle, and start to grow).  Although we often see Lepas attached to drift kelp, I couldn't recall seeing Lepas on Cumagloia before, so took a few documentary photos.  

 

Here's an even closer photo where you can see the barnacles nestled among the branchlets of the seaweed:

 

 

P.S.  Ocean temperatures off Bodega Head have been quite warm this week — up to ~16°C or >60°F.  It'll be interesting to keep an eye on these temperatures during the next couple of months.

Settling into summer

 

 

A nice trio of barnacle species on a mussel shell: 

- two Thatched Barnacles (Semibalanus cariosus), the ones with the ribbed look, at the bottom and upper left

- two Acorn Barnacles (Balanus glandula), the ones with the smoother look (center and upper right)

- seven Little Brown Barnacles (Chthamalus dalli), the smaller ones with a brownish gray coloration, four at the upper left, one between the upper two whiter barnacles, and two on the right side. 

(There are also some very tiny barnacles growing on the other other barnacles, but I'm just pointing out the larger barnacles for now.)

It's been a good spring for settlement of juvenile barnacles.  Now we'll see what the summer brings!

Happy Summer Solstice!

Along for the ride

 

 

Well, I've wanted to share this photo for a while, but it's been a little busy since Michael first let us know about this fascinating observation in mid-September.  

 

Meet Coronula diadema, sometimes known as a whale barnacle!

 

A young Humpback Whale washed up in Fort Bragg on 12 September 2022.  Michael was part of a team from the Noyo Center that went to document it and he took a few photos of the barnacles living on the whale.  It's not often that we get to see this species of barnacle up close as they live exclusively on whales!

 

You can see that the barnacles are quite rounded; they're often described as cask-shaped (or barrel-shaped).  They have sets of very prominent ribs and in some cases there is black coloration visible if the tops of the ribs have worn away or broken off.  The black is whale skin!  The barnacles anchor themselves in the whale's skin by incorporating it into the inner parts of their shells.

 

If you zoom in and look at the central area of the barnacle, you can see the orangish membrane and a pair of tiny white shells embedded in the membrane.  In other barnacle species, those plates (called scuta) help the barnacle close up entirely (like a trap door), but in Coronula diadema the plates are highly reduced.

 

 

 

  

These barnacles were alive when photographed, and the feeding appendages (known as cirri) were extended in one of the individuals (see below).  In Coronula, the appendages are relatively short.  Interestingly, I read that they have small hook-like structures at the tips of the cirri, perhaps indicating that they feed on larger types of zooplankton.

 

 

 

I can't help sharing one more close-up.  Check out the tiny "beads" at the base of the barnacle shells.  I don't recall seeing this texture in other barnacles.  That's new shell growth (barnacles add new shell at their base) and it's likely the beaded texture is worn away with time.

 

 

I hope you enjoyed this introduction to Coronula diadema!  Many thanks to Michael Brito and the Noyo Center for sharing these wonderful photos.

New neighbors

  

Another barnacle for you — this one is a Thatched Barnacle (Semibalanus cariosus).  These two young barnacles are growing on a mussel shell.  Note the nice new growth at the base.  Barnacles add new material to their shells where they are attached to the substrate.  In this case, the new growth is identifiable by its white coloration.

A tribute

I've received a couple of reports of Red-striped Barnacles recently, including one from north of Fort Bragg, which is very far north for this species.  (Thanks, Michele!)

So I've been thinking about barnacles lately, and in general I'm just a big fan of this fascinating group of marine invertebrates.  Here are a few shots to celebrate them:

 

 

 

 

 

 

 

 

In order of appearance:

 

Red-striped Barnacle (Paraconcavus pacificus)

Blue Buoy Barnacle (Dosima fascicularis)

Giant Barnacle (Balanus nubilus) 

Coastal patterns

 

Wandering Tattler (Tringa incana) near Newport, Oregon, on 4 June 2019.

Also nearby were these amazing Gooseneck Barnacles (Pollicipes polymerus).  They were noticeably large individuals!

 

One more photo — a close-up of the Gooseneck Barnacles highlighting the wonderful patterns created by their plates:

 

Pink volcano

Pink Volcano Barnacle (Tetraclita rubescens) photographed in northern Sonoma County.  Thanks to Eric for sharing this great photo!

The Distributor

Remember the mystery fossil from last week (see "Long in the tooth" and "A closer look")?  Well, we think we might have figured it out!  It took some sleuthing, and some help from experts.

To review, here's the fossil as we found it on the beach:

 

Amazingly, we had trouble even identifying what type of organism this might be.  For example, suggestions ranged from a walrus tooth, to a rudist (an extinct bivalve), to a barnacle, to a plant.

When we looked under a microscope, we noticed channels on the outer wall:

 

 

These eroded channels seemed reminiscent of a barnacle.  For comparison, here's a close-up of a wall plate from a local barnacle, Balanus nubilus, that lives in the rocky intertidal zone:

 

You can see why some people thought this fossil might be a barnacle.  But we were confused because we couldn't see any sutures, or divisions between wall plates, which would help confirm the identification as a barnacle.  [Many barnacles have 4-6 wall plates that fit together in a circle to form the familiar shell that is shaped like a little volcano.]

We sent the photos to Bill Newman at Scripps, one of the world's foremost barnacle experts.  Bill suggested that we had discovered the basis (basal plate) of a fossil barnacle!  Since it was only the basis, that would explain why we didn't see individual wall plates.

Here's a local barnacle (see below).  Many (but not all) barnacle species have a calcareous basal plate where they are attached to a rock (or other surface).  The wall plates sit on top of that base.  Most of the time, the basal plate is flat.  But note that sometimes the basal plate is elongated upwards and forms a shallow cup.  The blue arrow is pointing to the division between the lower basal plate and the upper wall plates.

 

Now imagine if that basal plate could be elongated a lot more, forming a conical tube (like our fossil!).  It's an unusual shape for a barnacle, but it's typical of an extinct barnacle called Tamiosoma gregaria (formerly Balanus gregarius).

 

We found some older illustrations of Tamiosoma fossils, so here's a comparative view from above — the fossil we found is on the right:

 

Left-hand illustration from Pilsbry, H. A. 1916. The sessile barnacles (Cirripedia) contained in the collections of the U.S. National Museum, including a monograph of the American species. Bulletin of the United States National Museum 93.

Tamiosoma has been found in fossil deposits from central California to Baja.  It's thought to have lived in shallow embayments between the early Miocene (16-23 million years ago) through the Pleistocene (2.6 million to 11,700 years ago).

Previous studies suggested that Tamiosoma's very elongate base might have been an adaptation to living in mud where sediment accumulated rapidly.  [Fun fact: Tamiosoma means "distributed body" and might refer to its unusual elongate form.]

Although we don't know what Tamiosoma looked like when alive, Eric thought it would be helpful to imagine how this amazing barnacle might have been positioned in the mud.  He scanned the fossil basis that we found, and then added wall plates (from a drawing of a Tamiosoma fossil) and cirri (feeding appendages).  The barnacles probably attached to small hard objects (e.g., a piece of shell) on the surface of the mudflat, and then continued to grow upward as sediment accumulated around them over time.  Sometimes multiple individuals were clustered together.  Check out Eric's excellent illustration:

 

P.S.  Many thanks to everyone who contributed to this story, especially Bill Newman, folks on the Fossil Forum, and Karen Whittlesey's thesis on this intriguing barnacle!

P.P.S.  The next question — where did the fossil we found come from?  Do you know of fossil deposits in the Bodega Bay area?

Kelp!

 

An amazing amount of Giant Kelp (Macrocystis pyrifera) washed up on local beaches during the last two days.  Although abundant in the Monterey area, Giant Kelp is less common in Bodega Bay.  I don't think I've ever seen this much Macrocystis on beaches in Bodega Bay (during the last 12 years).

The photo above shows the rippled or corrugated blades of Giant Kelp.

Below, note its relatively loose and sprawling holdfast (the portion of the kelp that attaches to the substrate):

 

(Why is the holdfast purple?  Maybe someone out there can provide some ideas?)

There was some large Bull Kelp (Nereocystis luetkeana) mixed in with the Giant Kelp.  Bull Kelp is the more common large kelp in our area.  In the photo below, the Bull Kelp is tangled up with the Giant Kelp, but you'll recognize Bull Kelp's very large float (pneumatocyst) and the smooth and shiny blades (the Bull Kelp blades also lighter in color than the Giant Kelp blades):

 

Here's a photo comparing the holdfasts of the two species:

 

The Giant Kelp holdfast is on the left and the Bull Kelp holdfast is on the right. 

I had wondered if this kelp might have been ripped out by the powerful 20-21 January storm, but upon closer inspection, I noticed quite a few pelagic barnacles (Lepas sp.) attached to the kelp, indicating it had been at sea for quite some time.  [There's a lot going on in this photo, so I've highlighted a good example of a pelagic barnacle with a circle.]

 

Based on the amount of kelp, its age, and strong recent currents from the south, I'm still guessing that this Giant Kelp originated from sites to our south.  But I'm not sure why so much has arrived on our beaches!  (Let me know if you have some ideas!)

Red-and-white revisited

Remember Paraconcavus pacificus, the red-and-white barnacle that grows on sand dollars?  I wrote about them in September 2016 (see posts from 25 September and 27 September).

Well, we're still encountering a few of these southern barnacles here and there.  Below is a recent example — an individual found washed up on Salmon Creek Beach tonight (3 February 2017):

 

On the bottom, you can still see a small remnant of the skeleton of a sand dollar attached to the base of this barnacle:

 

We're still very interested in any sightings of this barnacle north of San Francisco.  If you spot one, let me know!

The weight of the whorled?

For the record, this is the fifth month in which we've found Purple Sea Snails (Janthina umbilicata) in Bodega Bay.  Although most were found in March and April, we also spotted them in January, February, and May.

Here's one of four individuals that I encountered on 11 May 2016:

 

Did you notice the small pelagic barnacles (Lepas sp.) attached to the outer whorl of this snail?  We had heard that Lepas sometimes attaches to Janthina, but we didn't see this ourselves until April-May.

Here's a view of a snail shell floating at the surface, with the attached barnacles hanging below (their feeding appendages are extended like fans):

 

Although they start out small, these pelagic barnacles can grow to a size much larger than the snail.  Do the barnacles eventually weigh down the snail?  Does a snail have to add more bubbles to its raft to counteract the barnacles?  (For a picture of a bubble raft, review the post from 20 January 2016.)