Double-wide

We've been busy with field work during the weekend.  During one of our sea star surveys, Eric noticed an Ochre Sea Star (Pisaster ochraceus) that looked a little different.  Can you see what's odd?

 

It might be a little hard to tell from a photograph, but one of the arms (the lowest one) is much wider than all of the others.  Aside from the width of the "double-wide" arm, we couldn't see anything unusual, until we looked at the other side:

 

From above (photo #1), this sea star has 5 arms (the normal number), but from below (photo #2) it has 6 arms, although two of those arms are fused, creating the extra width seen from above.

Here's an even closer look at that unusual "arm":

 

Note that the arms are completely fused throughout their length.  There are two parallel ambulacral grooves — the grooves from which the tube feet arise (they're the yellowish grooves in the image above).

I was curious about the partial gap near the tip of the arm.  By partial I mean that from above this area is completely fused, but from below there is a slight separation.  Here's a close-up of that area:

 

When we looked at the very tip of the arm, we were intrigued.  Here's the tip, curling up slightly.  Remember that a sea star has a small red eyespot at the tip of each arm.  Can you see the eyespot?

 

Okay, that was a bit of a trick question.  There are two eyespots!  Below is an even closer view of the arm tip, showing both eyespots.  They're partially hidden by the spines (white bumps), but I think you'll be able to see both of them:

 

Well, we've looked at thousands and thousands of Ochre Sea Stars, and we've never seen one like this.  Have you?

We did some research, and there are a few records of sea stars with "double ambulacral grooves," but it's very rare.  Hotchkiss (2000) listed 11 individual examples, most of which were Asterias spp., and only one was Pisaster ochraceus.  That specimen was collected over 70 years ago in southern California.

Hotchkiss proposed that this abnormality was due to an injury and abnormal regeneration of the arm.  (The other possibility is a developmental irregularity during metamorphosis.)

The sea star we encountered had no obvious signs of an injury or regenerated arms (e.g., all of the arms were similar in length, ~5 cm long).  If the unusual arm arose from an injury, perhaps the injury happened quite a while ago when the sea star was much smaller.

Interestingly, the earlier Pisaster record is slightly different.  The arms are fused almost to the tip, but then they split:

 

Image from Fisher, W.K.  1945.  Unusual abnormalities in sea-stars.  Journal of the Washington Academy of Sciences 35: 296-298.

 

Who knows if we'll encounter another sea star with a "double-wide" arm.  If we do, I'm sure it'll raise our eyebrows again while we continue to wonder about this unusual phenomenon.

 

P.S.  The reference mentioned above is: Hotchkiss, F.H.C.  2000.  Inferring the developmental basis of the sea star abnormality "double ambulacral groove" (Echinodermata: Asteroidea).  Revista Chilena de Historia Natural 73: 579-583.

 

Sprinkled with pollen

This morning Eric and I were watching a Red-backed Jumping Spider (Phidippus johnsoni) when it started tracking something above it.  Then all of a sudden, it jumped and caught something!

I could see yellow, and here's what I saw when I zoomed in:

 

The spider caught a small bee!

Here's one more photo of the spider taking away its prey (presumably to a safe spot for eating):

 

I wondered what the spider thought about the pollen.  We couldn't stay to watch, but it would have been interesting to see if the spider ate the pollen-covered legs or left them behind.

P.S.  I first wrote about Red-backed Jumping Spiders in a post called "Zip line" on 30 January 2013.

Water views

 

Looking east across Bodega Harbor. The lighting this afternoon highlighted the different zones — mudflats (brown), eelgrass beds (dark blue), and the boat channel (light blue).

 

Looking northwest from Salmon Creek Beach.  Winds were blowing ~25 knots (~30 mph) in the early evening.  [Water temperatures reached ~10°C (~50°F) this morning.]

April showers

 

Approaching showers, 24 April 2017

 

A long tail?

Remember all of the Purple Sea Snails (Janthina umbilicata) we found last year?  For example, review the posts from 20 January 2016 and 6 March 2016 (or scroll down to the bottom of this page and enter "janthina" in the search field to see all of the previous posts).

You might also recall that we found six Janthina on 24 January 2017.

And I haven't mentioned it on the blog, but I also found one individual on 13 March 2017.

We're continuing our surveys to document the "tail" of the distribution of observations associated with the 2015-2016 El Niño.  That is, how long do species likely associated with the El Niño continue to appear in northern California, even after El Niño conditions have ended?

Well, we found one Purple Sea Snail today (25 April 2017)...so the tail continues to lengthen:

 

Let me know if you encounter any of these little purple pelagic snails.  We'd love to hear about any other sightings this year.

Crossed cups around the Pacific Rim

Okay, remember the mystery photo from last night?  Here's a reminder, with a slightly different view:

 

I'll zoom out a bit so you can see a little more.  And yes, for those of you who were wondering, the sand grains on the tentacles are a clue:

 

Any guesses yet?  When we first found this animal, we didn't know what it was.  We had to step through various options and rule out different groups.

Did you notice that the skin adjacent to the tentacles looks shiny?  Here's an extreme close-up so that you can see what I'm referring to:

 

Those shiny pieces are ossicles — tiny calcified plates.  To help identify this organism, we looked at a few of the ossicles under high magnification (400x):

 

Do you have a guess yet?  Think about a soft-bodied animal with a cluster of branched tentacles at one end and microscopic ossicles embedded in the body wall. 

It'll probably help if I tell you that although this animal doesn't have them, most of this animal's relatives have tube feet. 

Here's another look at those digitate (finger-like) tentacles:

Yes!  It's a sea cucumber!  We hadn't seen this species before.  It's a Sand Sea Cucumber (Paracaudina chilensis).  Amazingly, it's distribution includes the entire Pacific Rim (coastal South America, Central America, North America, China, Japan, Australia, and New Zealand).

As you might guess from the common name, and the pictures, this sea cucumber burrows in the sand.  It ingests large volumes of sand to capture organic material from the sand grains for food (hence the "sticky fingers").

This is what the entire sea cucumber looks like (photo below — note there was debris sticking to the cucumber, but that's likely a result of being in the drift line).  We found it washed up on the beach, and puzzled over it for a while.  With my hand lens I could see the tentacles — that helped because the tentacles didn't look right for a peanut worm or a sea anemone.  

Note the very long posterior end.  This sea cucumber lives upside down in the sand (up to 50 cm deep) — tentacles down, and posterior end up near the surface.

 

The shape of the ossicles helped clinch the identification as Paracaudina chilensis.  Many of them are beautiful three-dimensional "crossed cups."  Compare the ossicle images above with this published figure from a specimen in Australia:

 

Modified from O'Loughlin, P.M., S. Barmos, and D. VandenSpiegel. 2011. The paracaudinid sea cucumbers of Australia and New Zealand (Echinodermata: Holothuroidea: Molpadida: Caudinidae). Memoirs of Museum Victoria 68: 37-65.

 

P.S.  Are you wondering about the extra credit (i.e., the source of the brilliant red coloration in the tentacles)?  Paracaudina chilensis has hemoglobin-filled blood cells (in the body cavity and in the tentacles)!  The hemoglobin is likely an adaptation to living buried down in a low-oxygen environment.

 

Like little jesters' caps?

A close-up mystery photo, taken with a microscope.  Do you have any ideas about what type of organism this is?

 

I'll reveal the answer to this mystery tomorrow night.

P.S.  Extra credit if you can guess why the structures are red!

Resting on the beach

 

A beautiful Harbor Seal (Phoca vitulina) pup, 22 April 2017

Remember the mother/pup photos from several years ago?  You can review that post from 14 May 2013 here.

Today and every day

 

Celebrating Earth Day and science, today and every day!

 

Bearded

 

Bearded Clover (Trifolium barbigerum), Bodega Head, 19 April 2017

P.S.  Check out the interesting color patterns on this clover's leaflets (on the left-hand side of the photo).  I'm intrigued by the markings, so I did a quick search into what's known about the patterning.  It sounds like they're formally called "anthocyanin leaf markings" and they're known to be linked to certain genes.

Pinpoint

 

Pinpoint Clover (Trifolium gracilentum), Bodega Head, 19 April 2017

 

Which is which

There was a bit of fog on the coast today.  I didn't get a chance to take a picture, but here's a foggy one from late March 2013:

 

Although the boundaries in this picture are pretty distinct, today was one of those days when it is hard to tell which is which — where the ocean ends and the fog begins.

 

Spot-on

I was sorting through some pictures from last spring when I encountered this one:

 

I said to myself, "Huh...do Two-spotted Keyhole Limpets (Fissurellidea bimaculata, formerly Megatebennus bimaculatus) eat sponges?"  It certainly looks like the limpet (relatively small, dark brown shell surrounded by a bright yellow mantle) had been eating the green sponge (Halichondria sp.).  

So I read the species account in Intertidal Invertebrates of California which said this:

"This species often occurs on compound ascidians where the color pattern provides good camouflage.  In the laboratory, Megatebennus has been observed feeding on compound ascidians, and sponge spicules have been found in the gut of specimens collected in the field."

And then I laughed, because the next photo I found was this one:

 

The Two-spotted Keyhole Limpet above is in the center — with a dark brownish shell (barely visible) surrounded by a pale yellow mantle.  It's flanked by several compound ascidians, and you can see how well camouflaged it is.

The description in the species account by Don Abbott and Gene Haderlie was spot-on!

Migrating north

 

A distant shot in the rain, but I don't think I've posted a photo of a Greater Yellowlegs (Tringa melanoleuca) before.  In our area, Greater Yellowlegs are less common at the coast — I don't encounter them often in Bodega Bay.  

In the spring, Greater Yellowlegs are migrating north.  According to The Birds of North America, they'll nest in muskeg habitats in central Canada and southern Alaska.  

This photo was taken along Valley Ford Road in Petaluma on 16 April 2017.

Sometimes...

...it makes your day just to sit and watch:

 

 

River Otter (Lontra canadensis), 15 April 2017

Blue strand

A significant stranding of By-the-wind Sailors (Velella velella) on Salmon Creek Beach tonight (14 April 2017).  It was blue as far as you could see:

 

Most of the Velella were ~2-3 cm long, but there were a variety of sizes:

 

A small flotilla viewed from above:

 

Northwest winds were blowing at about 20 knots this afternoon, but they're predicted to calm down tonight.

Blue

 

I've been working on some photo organization, so here's one from the archives — an Acmon Blue (Plebejus acmon) photographed on Bodega Head on 15 March 2016.

Named after Chamisso

 

Camissonia strigulosa, photographed in the Bodega Dunes on 5 April 2017

The genus, Camissonia, is named after Adelbert von Chamisso — a German botanist who joined Otto von Kotzebue aboard the Rurik on a scientific voyage around the world in 1815-1816.  

Fun fact: When they visited California, Chamisso collected the California Poppy (Eschscholzia californica) and later named it after another scientist on the voyage, Johann Friedrich Eschscholtz.

The species name, strigulosa, is a reference to the short stiff hairs lying flat against the surface of the plant, some of which are visible on the reddish stem in the lower right corner of the picture (they look like a bit of white frosting).

I found several common names for this wildflower.  Which do you like better — Strigose Suncup or Sandy-soil Suncup?

Soaking up some rays

Air temperatures reached ~58°F (~14.5°C) in Bodega Bay this afternoon, but the sun and calm wind conditions made it feel even warmer.

I happened upon a few insects basking in the sun:

 

Two-banded Skipper (Pyrgus ruralis)

(This is the first time I've seen this butterfly species in Bodega Bay.)

 

California Darner (Rhionaeschna californica) 

And a close-up from the side:

 

 

Cardinal Meadowhawk (Sympetrum illotum)

It looks like it might be cloudy for the next few days, but the sun might return at the end of the week, bringing more chances for insect sightings.

 

At home in the sand

 

Beach Strawberry (Fragaria chiloensis)

 

Dark-eyed Gilia (Gilia millefoliata)

Both photographed in the Bodega Dunes, 5 April 2017

 

Spring break

  

14-foot west swell today, 7 April 2017

A sea of purple

 

Dwarf Lupine (Lupinus bicolor), 5 April 2017

The Distributor

Remember the mystery fossil from last week (see "Long in the tooth" and "A closer look")?  Well, we think we might have figured it out!  It took some sleuthing, and some help from experts.

To review, here's the fossil as we found it on the beach:

 

Amazingly, we had trouble even identifying what type of organism this might be.  For example, suggestions ranged from a walrus tooth, to a rudist (an extinct bivalve), to a barnacle, to a plant.

When we looked under a microscope, we noticed channels on the outer wall:

 

 

These eroded channels seemed reminiscent of a barnacle.  For comparison, here's a close-up of a wall plate from a local barnacle, Balanus nubilus, that lives in the rocky intertidal zone:

 

You can see why some people thought this fossil might be a barnacle.  But we were confused because we couldn't see any sutures, or divisions between wall plates, which would help confirm the identification as a barnacle.  [Many barnacles have 4-6 wall plates that fit together in a circle to form the familiar shell that is shaped like a little volcano.]

We sent the photos to Bill Newman at Scripps, one of the world's foremost barnacle experts.  Bill suggested that we had discovered the basis (basal plate) of a fossil barnacle!  Since it was only the basis, that would explain why we didn't see individual wall plates.

Here's a local barnacle (see below).  Many (but not all) barnacle species have a calcareous basal plate where they are attached to a rock (or other surface).  The wall plates sit on top of that base.  Most of the time, the basal plate is flat.  But note that sometimes the basal plate is elongated upwards and forms a shallow cup.  The blue arrow is pointing to the division between the lower basal plate and the upper wall plates.

 

Now imagine if that basal plate could be elongated a lot more, forming a conical tube (like our fossil!).  It's an unusual shape for a barnacle, but it's typical of an extinct barnacle called Tamiosoma gregaria (formerly Balanus gregarius).

 

We found some older illustrations of Tamiosoma fossils, so here's a comparative view from above — the fossil we found is on the right:

 

Left-hand illustration 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. Bulletin of the United States National Museum 93.

Tamiosoma has been found in fossil deposits from central California to Baja.  It's thought to have lived in shallow embayments between the early Miocene (16-23 million years ago) through the Pleistocene (2.6 million to 11,700 years ago).

Previous studies suggested that Tamiosoma's very elongate base might have been an adaptation to living in mud where sediment accumulated rapidly.  [Fun fact: Tamiosoma means "distributed body" and might refer to its unusual elongate form.]

Although we don't know what Tamiosoma looked like when alive, Eric thought it would be helpful to imagine how this amazing barnacle might have been positioned in the mud.  He scanned the fossil basis that we found, and then added wall plates (from a drawing of a Tamiosoma fossil) and cirri (feeding appendages).  The barnacles probably attached to small hard objects (e.g., a piece of shell) on the surface of the mudflat, and then continued to grow upward as sediment accumulated around them over time.  Sometimes multiple individuals were clustered together.  Check out Eric's excellent illustration:

 

P.S.  Many thanks to everyone who contributed to this story, especially Bill Newman, folks on the Fossil Forum, and Karen Whittlesey's thesis on this intriguing barnacle!

P.P.S.  The next question — where did the fossil we found come from?  Do you know of fossil deposits in the Bodega Bay area?