June thunderstorm

Late in the day, I looked up to see dark clouds on the eastern horizon:

 

Not too long after, a very loud clap of thunder rolled across the sky.  The thunder lasted for about 25-30 minutes, so I recorded a few examples.  The recordings are best heard with headphones, if you have them.  Otherwise, you might need to turn up the volume of your speakers.  [If you can't see the audio files below, click on the title of the post above to go to the website.]

It started to rain...and then the storm decided to add some pea-sized hail:

 

The thunderstorm moved off to the south, and the sky started to clear, but this wonderful storm ended with a grand finale:

 

 

Photos and recordings are from Cotati on 11 June 2017.

 

Pentamerism

 

Close-up of the sea star, Henricia sp., displaying pentamerism (radial symmetry organized in five parts around a central axis).

Photographed in Del Norte County on 26 May 2017.

Spiny -- Part 2

Okay, here's the mystery photo from last night:

 

This is a noticeably spiny crab claw.  Next question — which species of crab is it from?

The photo below is another hint.  (And note the sandy habitat where this crab lives.)

 

The picture above shows a distinctive crab carapace, with dramatic spines.

This species might be more familiar to those of you living south of San Francisco.  It's a Spiny Mole Crab (Blepharipoda occidentalis).  I've written about them once before; you can review previous photos from Doran Beach and Salmon Creek Beach here.

Most people are probably more familiar with the more common Mole Crab (Emerita analoga).  In contrast to Emerita, Spiny Mole Crabs can grow to be much larger; they have dramatic spines; and as the mystery photo shows, they have claws.  They use the claws to scavenge and tear apart food.  The spines on the outer edges of the claws and the carapace probably help to deter predators (such as fish).

 

I don't have a digital photo of a Spiny Mole Crab, but you can find a nice picture of the entire crab here (by Zen Faulkes) and on this EOL page.

I'm writing about Spiny Mole Crabs again because we're interested in whether anyone has found them north of Salmon Creek Beach.  

Recently, we counted many more molts than usual, so it's possible Spiny Mole Crab numbers have increased in our area, which also means there is potential for them to be found even further north than previously documented.

Below are two more examples of Spiny Mole Crab carapaces (two different sizes).  Let us know if you see a Spiny Mole Crab carapace or claw on a beach near you!

 

Spiny

I'm guessing that you might have an idea about what type of animal this is from?  The identity of the species will likely be more difficult, but I thought I'd give you a chance to think about it.  The answer will be revealed tomorrow night!

 

Check out those impressive spines!

 

Rain on the way?

 

Clouds above Cotati on 7 June 2017.  

We've received ~50 inches of rain in Bodega Bay during the 2016-2017 rainfall season...and it looks like that total might inch up a little higher tomorrow.

Young explorers

We've been enjoying watching a new family of California Scrub-Jays (Aphelocoma californica) explore our backyard.  At least four juveniles fledged from a nest in a tree in the corner of our yard.  (No wonder the adults were so busy during the last few weeks!)  Compared to the adults, note the shorter bill and the pale gape (pinkish stripe at the base of the bill).  The juveniles are also grayer and softer looking, and their wings are shorter.

 

To compare these juveniles with adult California Scrub-Jays, review photos from posts on 6 November 2015 and 13 December 2015.

CORRIGENDA (7 June 2017):  David wrote to point out that there has been a taxonomic change with scrub-jays.  So in this post I've changed the common name of this species from Western Scrub-Jay to California Scrub-Jay.  (Recently, the "Western Scrub-Jay" was reclassified into two species based on differences in distribution, morphology, behavior, DNA, etc.  The second species is now called Woodhouse's Scrub-Jay (Aphelocoma woodhouseii) and is found in the southwestern part of the country.)

Sparkling disco ball

Back in 2012, I showed a few pictures of a soft coral called Discophyton rudyi that we observed at Cape Mendocino (you can review those photos here).

In 2017, we found this species again at several locations in northern California and Oregon.  This time we also took some close-up pictures and Eric filmed a short video that we're excited to share.

Here's what Discophyton looks like up close.  Sometimes many of the polyps are extended, with tentacles spread outward:

 

Other times, most of the polyps are withdrawn, and it starts to look like a soft mound covered with little bubbles (the contracted polyps):

 

In the picture above, did you notice the granular texture surrounding each polyp?  The sparkling "grains" are sclerites, calcified structural elements that offer support and protection from predators:

 

[Note: A major predator of Discophyton is the nudibranch Tritonia festiva, which can often be found in close proximity.  Both are shown together in the photos from 10 May 2012.]

One way to recognize Discophyton in the field is to look for clusters of small disc-like mounds.  (Each mound is ~5-15 mm across.) The colonies can divide by fission, so it's likely many of the colonies in one area are clones (genetically identical).  In the photo below, can you find the splitting colony? A thin connection remains between two patches that are pulling apart from each other.

 

Yes, that's it!  The splitting colony is in the center of the picture.

The color of Discophyton can vary from white to pink to yellowish.  Note that this species is often found in shaded locations, e.g., under rock ledges.

 

And here's the video clip you've been waiting for.  Watch for subtle movements of the coral polyp tentacles.  At 10 seconds, in the upper right, look for one of the polyps to draw one tentacle down towards the center of the polyp — this motion moves prey caught on the tentacle to the mouth:

discophyton_sanford_2017 from Jackie Sones on Vimeo.

Although they're not necessarily conspicuous, it's nice to know this beautiful soft coral is a member of our local fauna.