Holiday picnic at the beach?

  

A nice Baird's Sandpiper (Calidris bairdii) at Point Reyes this afternoon (2 September 2024).

The sandpiper was feeding along the wrack line, especially near clumps of eelgrass (Zostera marina):

 

 

Often it was possible to see prey trying to escape its grasp.  Below, look for the fly and a probable amphipod (beach hopper) in the air just to the left of the sandpiper:

 

 

 

Sheaves of gills?

  

From the "Little wonder" post from ~1 week ago, I think you can tell that we've been looking closely at a couple of nudibranchs that live on the patches of bryozoan found on Giant Kelp (Macrocystis pyrifera).  Above, Eric is scanning the bryozoan colonies for signs of the nudibranchs.

We've found both Corambe pacifica and Corambe steinbergae, but these nudibranchs are small (often under 1 cm long), so it can be difficult to tell which species you're looking at. 

To make it a little easier for other folks to know what to look for when identifying these two species, Eric put together a series of video clips highlighting the differences between them (see the video below!).

In the video, first you'll see the bryozoans that the nudibranchs feed on.  The zooids emerge and extend their tentacles to feed.  When the nudibranchs appear, watch for these features:

Corambe steinbergae:
- the edge of the nudibranch is smooth around the entire perimeter
- the rhinophores are simple (no extra "decorations")
- there is a gap between the two rows of gill plumes on either side of the midline (and the gill plumes look a little more linear)

Corambe pacifica:
- the edge of nudibranch has a deep notch at the posterior end
- the rhinophores are sculptured or fluted
- instead of a gap between the two rows of gill plumes, in the center there are several gill plumes that are pinnate = with short branches aligned on either side of the main stem (they look a bit like feathers)

For reference, it also might help to see how the gills plumes of these two species were illustrated in the original descriptions:

 

Above, Corambe pacifica — the entire animal with posterior notch; a close-up of a fluted rhinophore; a close-up of the gill plumes from below (drawings by Olive Hornbrook MacFarland).

Above, Corambe steinbergae — the entire animal without a posterior notch; showing the simple rhinophores; and illustrating the gill plumes with a gap between the two rows.

One thing I didn't mention yet is that the gill position of these two species is unusual.  Many nudibranchs have gills (or other respiratory structures) on the upper surface.  In this case, the gill plumes are positioned on the underside!  But luckily Eric was able to film the nudibranchs from above and below, so this is an excellent view of the gills and the differences between the two species.

Check it out!  [And if you can't see the video player in an e-mail, just click on the title of the post to watch it on the NHBH website.]

Nicely done, Eric!  The best views of the differences between Corambe steinbergae and Corambe pacifica captured on film!

P.S.  Corambe pacifica's pinnate gill plumes have an interesting shape.  When viewing them I kept thinking about a Henri Matisse cut-out called The Sheaf (La Gerbe):

Fin in the fog

  

A couple of weeks ago, Eric looked up from the surf zone to see this animal swimming by.

I was surprised how close to shore it was.  Here's a photo with the fin in the distance and the surf zone (next to the beach) in the foreground:

 

 

It surfaced a few more times, so we had some better views, but I didn't have my camera ready and it was a bit foggy and distant, so here's my best shot for the record.  Did you guess its identity?

 

 

 

A Harbor Porpoise (Phocoena phocoena) near Drakes Beach on 17 August 2024.

 

I don't spend a lot of time at Drakes Beach, so I'm not sure how often porpoises are seen near the surf zone in that area.  Is it common?  If you have observations to share, please do!

 

P.S.  This sighting reminded me of an older post showing porpoises in Drakes Bay, but in this case they were photographed looking down from above the Chimney Rock Lifeboat Station — see "Breathe" on 26 November 2014.

 

Little wonder

  

Camouflage week continues!

You might recall that back on 14 July 2024, I introduced this amazing nudibranch, Corambe pacifica.  I also mentioned that I needed to get a better photo.  Well, here you go!  And, lucky us...Eric was also able to record some beautiful video clips.

Things to look for: 

- how well the color and patterning of the nudibranch match the bryozoan in the background

- two rhinophores (sense organs) near the leading edge (viewed from above, they look like a pair of white spots)

- a small notch along the back edge of the nudibranch

- when viewed up close, sometimes you can catch a glimpse of the branched gills inside the notch (more about the gills in a future post!)

Here's the video clip (below).  [If you can't see the video player in the e-mail message, just click on the title of the post above to go directly to the NHBH web page.]

Stay tuned for more about Corambe pacifica.

And thanks to Eric for the great video!

Like sand, like spider?

  

Here's another great example of camouflage with beach sand.  Eric photographed this jumping spider, Terralona californica, on 21 August 2024.

It's a little bit easier to see than the isopod, but it's still impressive to see how well the colors of the spider match the colors of the sand:

 

 

Although they are small and can be overlooked, we often see Terralona running along the high tide line on the beach, and sometimes catching small flies.  Here's the same spider from the front, showing its large eyes:

 

 

 

Thanks for the great photos, Eric!

 

The hidden one

  

Alright, this is a little bit of a test.  Scan the image above — can you spot the isopod (an oval-shaped crustacean with a segmented body)?  Look carefully, it's a tough one! 

Okay, here's another view, a little bit more zoomed in (below).  Can you find it now?  (Hint: Look for something that doesn't look quite like sand grains.)

 

 

And now even closer — I'm sure you'll see it now!

 

 

And, because this isopod is so cool, here's a slightly different view:

 

 

Meet Tecticeps convexus!  Amazing to see how well its coloration matches the surrounding sand — black, orange, gray, white, and even pale blue!

 

It is so well camouflaged that it might still be hard to see, so here's another image without the sand.  [Note the two dark eyes and the short antennae on the head, and the large pale spots in the center and on the last segment.  You can use those features to locate the isopod in the photos above.]

 

 

 

We're so lucky that Suzanne looked down to see this isopod on the beach!  

 

Eric and I have been interested in finding this species for many years, but it probably lives mostly in the subtidal zone (so a little out of reach for biologists who spend most of their time in the intertidal zone).

 

One more extreme close-up so you can really appreciate the colors and patterns:

 

 

 

With many thanks to Suzanne for noticing Tecticeps and bringing it to our attention, and to Eric for the fantastic photos of this seldom seen species.

 

Looming large

  

Getting ready for some low tide work this morning, couldn't help taking a photo of the super blue moon!  Photographed from Cotati on 20 August 2024.