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Tuesday, September 27, 2016

P-pac, Part 2

I wanted to follow up on the recent post about Paraconcavus pacificus (informally abbreviated as "P-pac") — the red-and-white barnacle found on sand dollars (and other objects in sandy areas).

After that post, several people wrote to say that they had seen these barnacles north of San Francisco this year.  These are important records for this species in north-central California, so it seemed worth sharing them with you!

#1Hollis discovered this specimen at Stinson Beach during the winter:



#2 — Jim encountered several nice specimens at Salmon Creek Beach in Bodega Bay this summer:



#3 — A few weeks ago, Megan photographed this specimen on a crab carapace near Drakes Estero (Point Reyes):



And here's one more a picture I took at Abbotts Lagoons (Point Reyes) in November 2015.  Because there are hydroids growing on the barnacle, it makes it harder to identify the species, but I think it's likely this is also Paraconcavus pacificus:


Keep your eyes open for other examples.  Who can find the furthest north record?  Could they be at Manchester, MacKerricher, or even further north?  

P.S.  Many thanks to Hollis, Jim, and Megan for sharing their observations and wonderful photographs.

Sunday, September 25, 2016

Unexpected plate appearance

Well, this is a story that's fun, interesting, and also humbling.  It begins with a red-and-white barnacle and a sand dollar.

Some of you might remember that we've been seeing a lot of Megabalanus californicus — a red-and-white striped barnacle that is generally uncommon in the Bodega Bay area.  It's been noticeably more common during the last few years — e.g., see the post from 1 June 2015.  Here's an example of Megabalanus growing on a California Mussel on Bodega Head:



Recently, we've seen a few sand dollars washing up on beaches with red-and-white barnacles on them.  Because of the increased abundance of Megabalanus, we didn't think too much about it.  (Mistake #1 we didn't stop to look closely at these barnacles).

In February 2016, Alex noticed one of these sand dollar/barnacle specimens, too, and brought one in to ask us about it:


Well, we made the same assumption and thought the barnacles were probably Megabalanus.  (Mistake #2 — We hadn't thought about the possibility that another species of red-and-white striped barnacle could occur in this area.)  We decided to keep this specimen for documentation and put it aside.

Then Jim Carlton came to visit in September 2016.  He's interested in barnacles, so we brought out the specimen to show him.  Almost as soon as he looked at it, he said something like, "You know, there's a southern barnacle that tends to be found on sand dollars."

We looked in the Light and Smith Manual and found a description for Paraconcavus pacificus (formerly Balanus pacificus).  Sure enough, it often occurs on sand dollars, but the Manual said the geographic range was from Monterey south.

Well, we know that some southern species have been showing up during the last two warm-water years, and sometimes El Niño conditions bring "waifs" further north beyond their typical range.  So although Bodega Bay would be out of range, could these barnacles on the sand dollar be Paraconcavus pacificus?

I raised my hand lens to take a closer look:


And wouldn't you know it, as soon as I looked through my magnifier, I knew they weren't Megabalanus.  The wall plates were very smooth (rather than having long, vertical ridges), and the color pattern was different, with subtle horizontal stripes, too (giving it more of a "checkered" appearance).

However, since this would be a rare record in northern California, we needed confirmation.  This is where barnacle identification gets a little more complicated.  You need to look at the opercular plates the four plates that cover the aperture or opening at the top of the barnacle.  

For reference, here's a photo of a common acorn barnacle, Balanus glandula, showing the four opercular plates a pair of "terga" and a pair of "scuta":



The sand dollar/barnacle specimen had washed up on the beach, so I wasn't sure there would be any opercular plates left behind.  Most of the barnacle shells were empty, but I was excited to see that one barnacle appeared to have plates inside (see arrow below)!  



Jim asked if we could use a microscope and if we had fine forceps and if there was a shallow dish available.  Yes!  Then he expertly extracted three tiny plates from the barnacle.

Here's what they looked like under the microscope. [Note: One plate is shown twice (both the interior and exterior sides) because not all four plates were present.]

Views of scuta (left) and terga (right).  Scale bar at lower right is 1 mm long. 


And for comparison, here are the opercular plates of Paraconcavus pacificus illustrated in an older barnacle identification manual.  Compare the overall shapes, the textures, the ridges, and furrows against the photos above.

Modified 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.   USNM Bulletin 93.
 

It's hard to believe, but as fate would have it, two of the world's leading barnacle experts were also visiting the lab that day Bill Newman and Bob Van Syoc!  They agreed that the plates were a perfect match.  The barnacles on the sand dollar are Paraconcavus pacificus, and represent a rare record for this barnacle north of Monterey/San Francisco.

I mentioned two localities just now because although most publications list Monterey as the northern range limit for this barnacle, there are a few scattered records (either in museums, in the literature, or online) that list more northern observations:

1912 California Academy of Sciences specimen Ocean Beach (San Francisco)
1916 Pilsbry questioned a specimen from Crescent City and said that the range north of Monterey needed to be investigated
1970 Merrill and Hobson paper on sand dollars Bodega Bay
1990 California Academy specimen Ocean Beach (San Francisco)
1994 California Academy specimen Ocean Beach (San Francisco)
1997 Mooi paper on sand dollars Ocean Beach (San Francisco)
2014 iNaturalist Ocean Beach (San Francisco)
2016 iNaturalist Ocean Beach (San Francisco)
2016 iNaturalist Point Reyes (Abbott's Lagoon?)
2016 this record, Salmon Creek Beach, Bodega Bay

 
You can see that Paraconcavus pacificus has been known from Ocean Beach (San Francisco) for a long time, and appears to be regular there.  So far we only know of three records north of San Francisco the note by Merrill and Hobson, the iNaturalist record for Point Reyes, and this record in Bodega Bay.

It would be very informative to hear about any other specimens of sand dollars with red-and-white striped barnacles north of San Francisco.  So let me know if you see one (and take a photo)!

P.S.  I can't help adding one more fun fact.  I learned a new word today "vinaceous."  Pilsbry (1916) used this term to described Paraconcavus pacificus.  It means "the color of red wine."  Here's another specimen (this one collected by Eric in Baja California, Mexico, in 1998) so you can consider the color:


P.P.S.  Many thanks to Alex for sharing his find and to Jim, Bill, and Bob, for identification assistance.
 

Friday, September 23, 2016

Golden-plover, Part 2

Okay, I know...some of you have been wondering if there are more photos of the golden-plover seen last night at Spud Point.  Here's a selection of images, showing the plover in different positions, from different angles, and with other shorebirds nearby. 








Above, the golden-plover is front and center.  Directly behind it with a decurved bill is a Whimbrel.  Two Black-bellied Plovers are in the background on the far left and far right.  And one Dunlin is in the lower right corner.


The next two photos (below) show mixed shorebird flocks.  Can you spot the golden-plover?  And how many other species of shorebirds can you find?  Answers are below the photos.  [Click on the photos for larger versions.]


The golden-plover is uppermost bird in the center of the image (it's also the brownest).  Most of the other birds (grayer and larger) are Black-bellied Plovers.  The bird on the far right is a Red Knot.  And the lowest bird (third from the right) is a Dunlin (it's the smallest bird in the flock).

 
Want to try again?  This is a little harder because the birds are roosting:


The golden-plover is the highest bird, second from the left.  The leftmost bird is a Red Knot.  The largest bird on the far right with dark stripes on its head is a Whimbrel.  There are four Black-bellied Plovers (one is low in the vegetation to the right of the golden-plover; two more are to the right of that bird, and the fourth is behind the Whimbrel); and, there are two Dunlin (in the foreground, at center and at far right).

High tide roosts often provide helpful side-by-side comparisons.

Thursday, September 22, 2016

Happy fall!


A golden-plover for the first day of fall!  

It was roosting with a flock of shorebirds (Black-bellied Plovers, Dunlin, Red Knots, and a Whimbrel) along the Bodega Harbor shoreline tonight just south of the Spud Point Marina breakwater.

I'm leaning towards it being an American Golden-Plover (Pluvialis dominica), but I'm still looking through photos.  Let me know what you think! 

P.S.  Golden-Plovers are rare migrants in Bodega Bay.

Tuesday, September 20, 2016

A fantabulous night

A couple of pictures from 17 September 2016

The night after the Harvest Moon:



A mating pair of Painted Tiger Moths (Arachnis picta)Can you tell which is the female?


In this species, females are larger than males.  She's on the right in the picture above, and here's a close-up of her (below).  [Click on the picture for slightly larger and sharper image.]


The scales on her wings are especially visible within the gray stripes, creating a stippled pattern.  

P.S.  I first introduced Painted Tiger Moths in 2012 see the post called "Painted Tiger, Hidden Dragon" on 1 October 2012; and "Now you see me..." on 18 October 2012.
 

Monday, September 19, 2016

Connections

Okay...have you guessed the identity of the "mystery" snail shown during the last two nights?

I have found four of these snail shells on Bodega Head since 2005, so here are two more examples.  These individuals are ~9 mm long:



And here are the same individuals from below:


These are California Cone Snails (Californiconus californicus, formerly Conus californicus).

Although there are many species of cone snails throughout the world (>500), this is the only species of cone snail found in California.

The northern range limit for this species is often listed as the Farallon Islands.  So when I first found one in Bodega Bay, I was excited to think about the possibility of documenting a new northern record.  

But when I asked Jim about about whether any cone snails had been found in Bodega Bay before, he recalled two different observations (1) In the 1970s, Cadet Hand, founding director of the Bodega Marine Lab, told Jim that cone snails washed ashore on Bodega Head "very rarely"; and (2) there are two cone snail specimens from Jenner (collected in the 1950s) in the California Academy of Sciences collection.

So my specimens aren't the first from north of the Farallon Islands, but cone snails are a rare find in this area.  It was fun for me to find out that Cadet Hand is one of the few other observers to have documented cone snails on Bodega Head.  The Bodega Marine Lab is celebrating its 50th anniversary this year (Happy Anniversary!), so I've been thinking about Cadet...and that led me to think about cone snails.

If you aren't familiar with cone snails, their feeding behavior is fascinating.  They have specialized "teeth" shaped like harpoons with which they can inject venom into their prey:


From Kohn et al.  1999.  Snail spears and scimitars: A character analysis of Conus radular teeth.  J. Molluscan Studies 65: 461-481.


In case you're wondering, California Cone Snail prey includes fish, molluscs, polychaete worms, and crustaceans.

Although the individuals shown above are small, California Cone Snails can reach lengths of ~35 mm (~1.3 inches), so keep an eye out for these intriguing snails.  Perhaps you'll document them at a site that's even further north than Bodega Bay!

Sunday, September 18, 2016

Snail story: Chapter 2

Well, I don't have quite enough time tonight to do this snail justice.  So I'll apologize for the delay, but I'll also provide a second photoanother clue to the identification of this species (see below).

I'll also tell you that this particular individual was ~8 mm long (measured from from left to right in the picture below), but that this species can reach a length of ~35 mm.  

This individual was found washed up on the beach in Bodega Bay.  The shell is quite worn (like sea glass).


More tomorrow!