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!

Seeing orange spots

 

I was helping with some shorebird surveys in Bodega Harbor today when I noticed some egg masses on the tidal flats where I was standing.  When bent down to look more closely, I saw a few bubble snails nearby.  They looked more orange than others I've seen in Bodega Harbor, so I snapped a few quick photos for the record.

I'm wondering if this could be Haloa japonica (formerly Haminoea japonica), but I'll need to check with some folks to confirm.

 

Striped barrels

Back on 12 November 2014, I showed an egg mass from a local snail that lives on the tidal flats in Bodega Harbor — a Striped Barrel Snail (Rictaxis punctocaelatus).  

In that post, I mentioned that I had found the egg masses, but I hadn't found an adult snail yet.  That was true until December 4.  Once I learned how to see the adult snails, I realized that they're common to abundant in Bodega Harbor this year. 

Although most of the snails were buried just below the surface of the sand, here's an example of one that was crawling on the surface:

 

I've been doing shorebird surveys in Bodega Harbor for over 10 years now.  I hadn't encountered these snails until this year, so I'm wondering if there's something unusual about the conditions this year (or whether I just missed them if they weren't as common and I didn't know how to look for them).

But if you'd like to see some of these intriguing snails, this would be a good year to look for them in Bodega Harbor!

The masses

Back in September, while doing a shorebird survey in Bodega Harbor, a couple of different egg masses on the tidal flats caught my eye.

They attracted my attention not only because they were so noticeable, but also because I have been doing shorebird surveys in the same area for over 10 years now and I didn't recall seeing these egg masses before.

One was bright yellow and wrapped around algae or seagrass:

 

The other was bright white, shaped like a corkscrew, and embedded in the sand:

 

I finally tracked down the snail making the yellow egg masses.  It was a bubble snail, Haminoea vesicula.  Here are two images to help you visualize how the yellow egg masses consist of rows of developing embryos:

 

 

I showed examples of adult bubble snails on 4 June 2015, so check out those pictures here.

I kept meaning to return to find out which species had produced the white corkscrew egg masses, but hadn't found the time.  Today Jeff helped me out — he identified the distinctive egg masses as belonging to Rictaxis punctocaelatus.

Below are two close-ups of these spiraled egg masses: 

 

 

I haven't seen adult Rictaxis yet (it's been on my wish list!), but if you'd like to see examples of these wonderful local gastropods, check out pictures here.

Working on wings to fly

A few days ago, Kate and her crew noticed an intriguing animal in their plankton sample.

 

We could tell that it was snail veliger (larva), but we weren't certain about the species.

In between broad wings, it had a very pretty shell:

 

A tapering foot was visible below:

 

The veliger had large velar lobes — and the lobes were edged with bright orange polka dots.  With active bundles of cilia, it was using the velar lobes to swim.  (This is best viewed in the video at the end of this post.)

 

As mentioned, we weren't familiar with this snail, so we started sending pictures around for help.  No one responded right away, so Eric decided to keep it in the lab for a few days. 

A couple of days later, the veliger had undergone metamorphosis into a juvenile snail!  This made it much easier to identify.

 

Note that the ciliated velar lobes are gone; the orange and gold speckles have expanded; and there are two siphons — the anterior one (to the left) is formed by a flap near the front end, and the back one (to the right) is formed by the folding of the wings.  (In this case, the wings are extensions of the foot.)  Water is pulled into the front siphon, passes over the gill, and then is expelled out the back siphon.

As the snail glided along and explored its environment, we occasionally caught a glimpse of its two dark eyes:

 

Pacific Stomach Wings (Gastropteron pacificum) are capable of crawling and swimming.

Eric was fortunate to have filmed this snail when it was still a larva (swimming with its velar lobes) and after it metamorphosed into a juvenile.

Check out his video below!  (Click on the title of the video to see a high resolution version.)

pacific stomach wing sanford from Jackie Sones on Vimeo.

Many thanks to Kate and her team for sharing this wonderful find from the plankton off Bodega Head!

 

P.S.  If any gastropod enthusiasts out there are wondering — Pacific Stomach Wings are cephalaspideans, related to headshield slugs and bubble snails.

Inhaling bubbles

Here's a close-up mystery photo (below).  Can you guess what type of animal this is?

 

It might be tricky unless you're familiar with it.

Here's the entire animal:

 

Meet Navanax inermis.  Although it looks very similar to a nudibranch, Navanax is in a related but different group (Order Cephalaspidea, Family Aglajidae) that includes headshield slugs and bubble snails.

I didn't get a great picture of it, but animals in this group have a well-developed cephalic shield — note the broad head on the left end — that aids in plowing through the sand.  Most have shells, but the shells may be reduced and internal, which makes them hard to see on live animals.  And many have wing-like parapodia that can be folded up over their backs.

Grace spotted Navanax in Bodega Harbor on 4 June 2015.  I'm glad she mentioned that she had found something interesting, because this is an unusual record for this area.  Bodega Harbor is the northern range limit for this species.  In fact, many books still describe the range limit as either Monterey or Bolinas.  But there are local Navanax records from the 1970s (see The Natural Resources of Bodega Harbor by Standing et al., 1975) and Bodega Harbor is also listed as the northern limit in The Light & Smith Manual (2007).

Navanax is known to be a voracious predator.  They eat bubble snails and nudibranchs.

Grace has noticed that one of the bubble snails (Haminoea vesicula) is common in Bodega Harbor right now.  If you haven't seen a bubble snail, here are two quick photos (the second shows the bubble-like shell for which the group is named).

 

 

If you want to see something really impressive, watch Jeff's video of Navanax inhaling a bubble snail.

I don't know how many Navanax are in Bodega Harbor right now.  If you see any, I'd love to hear about it!