On the half shell

 

 

So we were walking at Dillon Beach this week and Eric looked down to see this large clam shell wedged in the sand under water.  It wasn't completely white inside, so he was curious about what looked like tiny yellowish dots in the center of the shell.

 

He picked up the shell and I took a look with my hand lens, but I couldn't tell what they were.  I couldn't even tell if they were hard (with a shell) or soft (gelatinous).  But Eric wiped his finger over a few of them and realized they were soft.  Hmmm...were they egg masses of some sort?

 

But because we couldn't see any detail, we decided to scoop up some seawater to fill the clam shell and see if any other hints would be revealed.

 

We were a little surprised, but here's what we saw next:

 

 

Tentacles!  It might be hard to tell from the photo, but we actually couldn't see the tentacles themselves.  They were too small and didn't stand out from the white shell in the background.  It was the shadows cast by the tentacles that were most apparent.  Here's a closer view:

 

 

 

The tentacles made the answer easier.  These are tiny jellyfish polyps.  You might remember that I posted about some different polyps on the docks in Bodega Harbor in late June — see "Soon to be jellies?" on 29 June 2023.

This is the first time we've observed jellyfish polyps on a clam shell.  It's likely we've just missed them, but now we'll know to watch for them.

 

 

The polyps need to attach to a hard surface, so on a long sandy beach, a clam shell might be prime real estate!

Leaving the lair

  

Okay, have you been wondering about the Turquoise Dragon and her developing larvae?  (See posts on 24 July 2023 and 29 July 2023.)

The larvae hatched on 2 August 2023 and Eric caught some of them crawling and swimming away in the video clip below.

The epitoke (reproductive stage of the worm) brooded the embryos/larvae for at least 12 days.  It's likely that the larvae will spend some time swimming in the plankton and growing (adding more body segments) before settling to the bottom and metamorphosing into juvenile worms.

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

Thanks to Eric for sharing this great video clip!

The journey begins

  

Well, this bird was pretty far away, but since I haven't posted a photo of a juvenile Pigeon Guillemot (Cepphus columba) yet, here you go!   

Note the mottled feathers on the back and upper wing areas.  

For comparison with adults (in breeding plumage), see "Sharing a shelf" on 26 July 2022.

Photographed off Bodega Head on 5 August 2023.

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.

Bee careful

 

 

Well, this is a lesson in being careful and taking the time to look closely.  Recently I have been noticing these small bees zipping around visiting Seaside Daisies.  As you can see, they stand out because of the large loads of bright yellow pollen on their hind legs.  

Years ago I observed some bees with "pollen-covered chaps" (Melissodes pallidisignata, see the post from 31 July 2013) and I had been assuming the bees I've been seeing recently were that species.  However, when downloading my photos today I realized this looked like a different species.

Here's another view:

 

 

I'm not that experienced with identifying bees, but I'm wondering if this is Anthophora urbana?  If anyone out there can assist with the identification, I'd appreciate any help.

 

Interestingly, if it is Anthophora urbana, it is abundant on Bodega Head this year and I'm not sure if I've just missed it in the past (didn't look closely enough) or if it's more common this year than in years past?

The Dragon's Treasure

 

 

As you’ll recall, last week Eric’s class found an amazing reproductive worm swimming in the plankton (see "Turquoise dragon!" on 24 July 2023).  She was protecting a brood of fertilized eggs, but they were very early in development.   

 

Eric kept the worm in the lab, and now about a week later her embryos have developed into a treasure hoard of crawling 4-eyed larvae (called trochophores).  We suspect that sometime soon the larvae will break free of the brood sack and swim away!   

 

Here's a short video clip where you can see the larvae.  They're quite active!  [If you can't see the video player below, click on the title of this post to watch the video on the NHBH website.]

 

Turquoise dragon!

 

Last week, Eric’s summer class collected plankton tows in Bodega Bay and examined them under the microscope.  One of the students (Pachia) spotted this very striking polychaete worm that was turquoise in color and carrying a mass of bright orange eggs!    

 

The worm was quite small (only ~2.5 mm long).  Those are millimeter marks on the ruler below:  

 

 

 

This worm is known as an epitoke, a type of reproductive individual that occurs in some species of polychaetes.  Epitokes swim up from the bottom to the surface where mass spawning events occur.  In most cases, both male and female epitokes free-spawn their gametes into the water where fertilization occurs.   

 

However, the species shown here is unusual in that females do not free-spawn, but instead hold onto an egg mass and protect their fertilized embryos for some time while they develop.  Although we aren’t able to identify the species, this worm is likely a member a member of a particular group of polychaetes (Family Syllidae, Subfamily Autolytinae). 

Luckily, Eric was able to capture some video of this beautiful worm, whose appearance reminds us of a tiny turquoise dragon.  [If you can't see the video player in your e-mail, click on the title of the post to go directly to the NHBH website to watch the video.]

 

With many thanks to Pachia for spotting this wonderful worm, to Bruno and Richard for helping with the identification, and to Eric for putting together the story with photos and video.