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Sunday, February 19, 2017

Foamy photos

A few foamy photos from yesterday (18 February 2017).  It was windy enough that large pieces of foam were becoming airborne:

Can you find the "foam elephant" in the photo below?  :) 

As you can probably tell, many of these pieces were much larger than snowflakes:

Sometimes the foam was lifted high into the sky who knows how far it traveled? 

P.S.  One of the dangers of trying to take pictures of flying foam is that sometimes your camera (or your face) is in the direct line of flight!  It's a funny experience because it's a bit scary to realize that a large flying object is headed towards you, but then you remember it's just foam, and you feel a gentle but noticeable "thwap"and then the clump of bubbles breaks apart upon contact.

Saturday, February 18, 2017

Northwest winds

If felt like spring today, with strong 20-25 knot northwest winds.

I'm guessing the swell was ~12-14 feet when I took this picture ~mid-day today (18 February 2017).

Thursday, February 16, 2017

Pelagic Red Crab zoea!

Okay, here we go the answer to last night's mystery photo.  As a reminder, here's the image:

We received several correct guesses.  This is the zoea (free-swimming larval stage) of a Pelagic Red Crab (Pleuroncodes planipes)!  The photo below shows the entire zoea:

We haven't been able to find many pictures of Pelagic Red Crab larvae, so we thought it would be fun to share a few.  Eric also recorded some video (see below)!

Here's the basic sequence of events:

After finding live Pelagic Red Crabs on 24 January 2017, I was measuring them and counting the number of males and females.  I discovered that several of the females were carrying eggs.  Similar to lobsters, they brood their eggs attached to the underside of the abdomen (see below):

We wondered if the embryos would develop in Northern California waters.  Based on a previous study that found they did well at 12°C, it seemed like they should develop and hatch in ~22 days.

Right on schedule, the embryos hatched today (after a minimum of 22 days)!  This is what we saw when we came into the lab this morning — an adult female surrounded by hundreds of larvae, each ~2 mm long:

And here's a close-up of some of the larvae in the jar:

Carl Boyd described the larval stages of Pelagic Red Crabs in 1960.  This drawing shows the first zoea:
Modified from Boyd, C.M.  1960.  The larval stages of Pleuroncodes planipes Stimpson (Crustacea, Decapoda, Galatheidae).  Biological Bulletin 118: 17-30.

And here's a close-up of a zoea in a similar position (shown in dorsal view, from above):

As mentioned, Eric took advantage of a rare opportunity to film some live Pelagic Red Crab larvae.  You'll see the very active newly-hatched zoeae zipping around.  (Among the swimming sequences and close-ups, watch for the rapidly beating heart.)  Note: If you receive this via e-mail and can't see the video file below, click on the title of the post above to go directly to the web site.

I can't help showing a couple more pictures — two extreme close-ups.  Check out the beautiful telson (last abdominal segment or "tail")...

...and the wonderful second antenna (the outermost antenna, adjacent to the eye):


We feel very fortunate to have observed and photographed these fascinating larvae.  We hope you enjoy them, too!

Wednesday, February 15, 2017

Guess who?

Time for a close-up mystery photo!  

Do you have ideas about what type of organism this is?  

[I'll reveal the answer tomorrow night.]

Tuesday, February 14, 2017

Sunrise in the western sky

The moon in the western sky at sunrise, as seen from Cotati on 14 February 2017.

Monday, February 13, 2017

Pink roses

Although there were more Hopkins' Rose (Okenia rosacea) nudibranchs around in 2015 and 2016, there are still some individuals present in the Bodega Bay area.  This one was photographed on 12 February 2017, when we spotted 8 others during a survey in the rocky intertidal zone.

For some background information about these nudibranchs, review the post from 3 January 2015.

Happy Valentine's Day!  
    ♥    ♥    ♥        ♥    ♥   

Sunday, February 12, 2017

Scarlet fire

About two years ago, I shared a post about the Scarlet Sea Cucumber, Lissothuria nutriens (see post on 22 January 2015).  At that time, I noted this species was rare in Bodega Bay, but we also wondered if this southern sea cucumber might increase in abundance if sea water temperatures became warmer.  It appears that has happened!

The Scarlet Sea Cucumber reaches its northern range limit in Bodega Bay.  There are some records from Duxbury Reef in Bolinas, but so far we haven't been able to find any records from further north.  (This would be a good time to look for them in northern California!)

Remember that this is a small sea cucumber.  Here's a picture from the rocky intertidal zone with some fingertips for scale.  It shows several Scarlet Sea Cucumbers on the rock look for three reddish blobs in the center of the picture:

When the cucumbers are out of water, their tentacles are retracted.  And note that they cover their bodies with bits of debris.  (Recognizing this "covering" behavior is helpful when searching for these sea cucumbers — it differentiates them from red sponges and sea squirts.)

Here's another example, this time a close-up of a single Scarlet Sea Cucumber:

Because this species has been rare in our area, we wanted to be certain about the identification.  So Eric double-checked the ossicles (the calcareous plates inside the body wall, tube feet, and tentacles that help identify different species of sea cucumbers).

Below is a diagram illustrating the different types of ossicles found in Scarlet Sea Cucumbers:

Ossicles of Lissothuria nutriens.  (A) Curved supporting plate from tube foot, (B) end plate from tube foot, (C) smaller, hourglass-shaped bodies from dorsal body wall.  Modified from Deichmann, E. (1941).  The Holothuroidea collected by the Velero III during the years 1932 to 1938. Part I. Dendrochirota.  Allan Hancock Pacif. Exped. 8: 61-194.

For comparison, here are a few of the ossicles from one of the local specimens.  You can see that the shapes match the drawings above, confirming the identification:

If you get lucky and spot a Scarlet Sea Cucumber in a tidepool, along with the red oblong body you might see the tentacles extended.  Interestingly, the tentacles vary in color from fiery orange to scarlet red:

These sea cucumbers feed by catching organic material on their tentacles and then moving it to their mouth in the center of the tentacles.  Eric filmed some of this behavior under a microscope in the lab, and he made a wonderful video clip so that you can see the tentacles in action.  (Also watch for the shiny ossicles embedded in the tentacles and tube feet.)

We have counted quite a few Scarlet Sea Cucumbers in the low intertidal zone while conducting surveys this past week.  We're also wondering if the warm ocean temperatures during the last couple of years might have allowed this species to move even further north, beyond Bodega Bay.  We'd be very interested in any Scarlet Sea Cucumber observations in northern California, so let us know if you spot one!