Drifting north

  

While walking a beach near the Garðskagi lighthouses (near the village of Garður on the Reykjanes Peninsula), I looked down to see a cluster of Blue Buoy Barnacles (Dosima fascicularis) in the wrack line.

Although we knew there were previous records of this species in Iceland, it felt a little surprising to see them.  Most of the records for this pelagic barnacle are from further south.  In California, we found these barnacles in Sonoma County during the warm-water events in 2014-2016 (e.g., see "Blue buoys!" on 31 August 2014).

Here's a close-up where you can see the thin, transparent plates.  You can also see the white foam-like float that the barnacles make to stay afloat at the surface of the ocean (upper left corner of the image).

 

 

 

And Eric took this beautiful photo of the cluster floating in the water next to the beach so you can envision them in their natural habitat.  [You can also see a piece of rockweed (Fucus sp.) at the lower right corner of the barnacle cluster (look for the orange color).  The barnacles might have attached to this piece of seaweed initially and then created their float around it.]

 

 

 

Fun to find this offshore barnacle at 64° North!

Reading the shells?

  

While in Monterey last weekend, we were thinking about southern species that might become more common farther north if a major El Niño event arrives this fall/winter.  For fun, while walking the beach we gathered some shells and ended up with 11 of these species.  We used all of them to spell out El Niño in the photo above.

Three barnacles: Megabalanus tintinnabulum, Paraconcavus pacificus, Tetraclita rubescens

Six snails: Acanthinucella punctulata, Californiconus californicus, Hespererato vitellina, Atrimitra (formerly Mitra) idae, Pseudomelatoma torosa, Pseudopusula (formerly Trivia) californiana

Two limpets: Fissurella volcano, Lottia gigantea

You can click on the image above for a larger version, and here's an example with labels, a close-up of the "E":

 

 

 

P.S.  If you're interested, you can follow NOAA's El Niño predictions at this link (updated monthly). 

Blue on blue

  

Eric and I have been busy with lots of early morning field work recently.  As we were walking on a beach in Marin County this morning, I looked down to see a Blue Buoy Barnacle (Dosima fascicularis) attached to a By-the-wind Sailor (Velella velella).

Blue Buoy Barnacles are pelagic (offshore) barnacles that float at the surface of the ocean.  They are unusual in northern California and can be indicators of warm-water conditions, or water that's normally farther offshore coming closer to the coast.  I'll have to check my notes, but I think the last time we saw one in our area was ~10 years ago (back in 2016).

With the high numbers of Velella washing ashore at this time, the chances of finding Dosima are greater as this barnacle often attaches to Velella floats. 

We're interested in other observations of Blue Buoy Barnacles in northern California, so keep your eyes open and if you happen to come across one, I'd love to hear about it! 

P.S.  For an introduction to Blue Buoy Barnacles, see the post called "Blue buoys!" on 31 August 2014.  And more information (and a great video!) can be found in the post called "Driftin' blues" on 23 September 2014. 

Intertidal volcano

  

Pink Volcano Barnacle (Tetraclita rubescens) on 31 May 2025.

 Thanks to Eric for another great barnacle photo! 

Thatched

  

Thatched Barnacle (Semibalanus cariosus) on 29 May 2025.

Thanks for the great photo, Eric!
 

Homes on the rocks

  

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

Thanks for the great photo, Eric!

A long way to grow!

  

Close-up of barnacles on a Californa Mussel (Mytilus californianus) shell, photographed on 29 April 2024.

There are at least two age classes of barnacles here — the larger Little Brown Barnacle (Chthamalus dalli) adults and the very tiny newly-settled recruits.  The recruits were so small they were actually hard to see in the field — just small specks scattered across the mussel shell.  They have a long way to grow!  :)

Comparing goosenecks

 

Close-up of a pelagic gooseneck barnacle (Lepas sp.) on a piece of driftwood, 11 March 2024.  These barnacles attach to floating materials in the open ocean.  

Lepas is similar to Pollicipes polymerus, the gooseneck barnacle that lives in the rocky intertidal zone, but you can see a number of differences: 

- Lepas has fewer calcareous plates.
- Lepas has a smoother stalk texture.
- Pollicipes tends to have dark pigment (red, brown, or black) at the edges of the largest plates, whereas these areas are paler in Lepas (but can be orange).  

See below for a comparison!

 

 

Washing up

 

 

With ocean temperatures quite warm recently (in the 17-18°C or 62-64°F range) and with El Niño conditions present in the Pacific Ocean, we're keeping an eye out for more southern/warm-water species.

 

Above is a piece of a Purple-striped Jelly (Chrysaora colorata) that we encountered at Limantour Beach on 26 August 2023.  (To see an entire individual, see the post called "Southern drifter?" on 27 July 2014.

We also came across this wooden pallet covered with pelagic gooseneck barnacles (Lepas sp.).  These barnacles aren't necessarily associated with warm water, but they are typically found offshore, so seeing them on the beach indicates that offshore species are appearing closer to the coast.

 

 

 

 

 

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.

Barnacles, yum!

  

Back in late June, someone kindly alerted me to the presence of some Onchidoris bilamellata over at Doran Beach.  I swung by and took a few quick photos.  I still need to go back to see if I might be able to get some better pictures, but I thought I'd share this one for now.  

Onchidoris is unusual among nudibranchs in that it feeds on barnacles (!).  The mottled brown-and-white nudibranch is in the top center of the photo.  In the bottom right you can also see a nice chiton (note the shell plates) next to the barnacles. 

I wrote about Onchidoris ~8 years ago, so for some more photos and a little more info, check out the post called "The barnacle-eaters" on 24 June 2014.

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!

In the grooves

  

Along with Velella and other wash-ashores, Eric spotted this glass bottle washed up on the beach yesterday (2 April 2023).  The bottle's shape was unusual, but the grooves and indentations were perfect attachment spots for pelagic gooseneck barnacles (Lepas sp.):

 

 

P.S.  Anyone know what kind of bottle this is?  I tried to locate something similar on the Internet but couldn't find a match.  If you have any ideas, let me know!

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.

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.

Like granite

  

Fingered Limpets (Lottia digitalis), Eroded Periwinkles (Littorina keenae), and a few acorn barnacles (Chthamalus dalli) on Bodega Head granite, photographed 9 July 2022.

Home, home on the seaweed

  

Recently Eric noticed these small crustaceans clustered on a seaweed washed up on the beach.

Here's what it looked like when first discovered:

 

 

This is the seaweed Sea Sacs (Halosaccion glandiforme), which consists of water-filled sacs (with a small volume of gas) normally attached to intertidal rocks.  When they're pulled off the rocks by waves, they'll float at the surface of the ocean.  If you look closely in the photo above, you can see the small clusters of crustaceans.  Under the microscope, more details are visible:

 

 

 

 

These are barnacle cyprids, the final swimming stage, of Pelagic Gooseneck Barnacles (Lepas sp.).  These cyprids will attach to floating structures like driftwood or a feather or this seaweed and then undergo metamorphosis into juvenile barnacles.  The appendages they use for swimming in the cyprid stage will morph into feeding appendages (called cirri) in the juvenile/adult barnacle.  Here's a diagram with arrows pointing to the appendages as they change during metamorphosis from their function in swimming to feeding:

 

 

 

What's cool is that the cyprids are partially transparent, so you can see those dark, feathery appendages in the close-up photos:

 

 

 

Fun!

 

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.

Plate tectonics?

  

A photogenic Pink Volcano Barnacle (Tetraclita rubescens), thanks to Eric!  Photographed on 3 July 2021.

Pink Volcano Barnacle shells are made up of four wall plates.  The boundaries between the wall plates are hidden by the sculpturing on the outside, but if you find a shell washed up on the beach, you can turn it over to see where the four plates meet.  [Or perhaps I'll post a picture of that view sometime!]  Most other barnacle species in this area have six wall plates.

Peanut brittle?

  

Okay, I know I've shown a few peanut worms recently, but this was a nice view of several different peanut worms (Phascolosoma agassizii) extending their introverts from a crevice and using the short ring of tentacles at the end to feed.  You can also see several arms of a brittle star extending out of the crevice and even lying across one of the peanut worms.

P.S.  If you want to play the "phyla game" again, look around to see what you can find.  Below I'll list the phyla in this image.

1. Peanut worm (Phascolosoma agassizii), Phylum Sipuncula
2. Brittle star, Phylum Echinodermata
3. Barnacle, Phylum Arthropoda
4. Limpet (checkered, in lower left corner), Phylum Mollusca
5. Tube worm (orange tentacles, upper right corner), Phylum Annelida
6. Flatworm (gray/white, same species as last night), Phylum Platyhelminthes