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Sunday, August 31, 2014

Blue buoys!

The conditions just seemed rightwarm ocean water since July, some unusual species appearing, and then a day and night of very strong northwesterly winds.  I wondered if something interesting would wash up the beach?

On 30 August, Eric and I had a busy day of moving and errands, but in the afternoon we made time for a quick walk on Salmon Creek Beach.  We were seeing some By-the-wind Sailors (Velella velella) and salps (Thalia democratica), and we came across one small Ocean Sunfish (Mola mola), but nothing too unexpected.  Just as we were about to turn around, I looked down to see something like this:


There are some By-the-wind Sailors and some Mole Crab molts, but did you spot the bright blue barnacle in the lower right corner?  Wow!  Neither Eric nor I had seen a barnacle like that before!  (For scale, the barnacle was ~2 cm long.)

Were there others?  We started looking, and found a few more: 


And yes, the barnacle in the photo above is attached to the float of the By-the-wind Sailor.  Some of the blue barnacles we found were attached to By-the-wind Sailors, while others had a mysterious material at the end of the stalk.

Since we'd never encountered this species of barnacle before, we brought a few back for identification and documentation.  Some of the barnacles were still alive, so I placed them in a small aquarium for photos.

The barnacle in the image below has some of that "mystery material" at the end of its stalk (or peduncle).  Note that it's very buoyant!


Sometimes more than one barnacle was attached to one float (see below).  The next photo also highlights the barnacle's plates.  In this species, the plates aren't very calcified, so they're almost transparent. 


We were excited to identify this as a Blue Buoy Barnacle (Dosima fascicularis, formerly Lepas fascicularis).  We often encounter other species of pelagic barnacles (e.g., see post from 11 August), but this open ocean species is known for an unusual capability.  Although initially the larva attaches to a floating object (such as a feather, driftwood, algae, or By-the-wind Sailor), the barnacle then produces a float of its own!

In the next illustration, the barnacle started out growing on a feather, but then secreted a foam-like float made of bubbles (it's thought that the bubbles are filled with carbon dioxide).


Modified from Boetius, J.  1952-1953.  Some notes on the relation to the substratum of Lepas anatifera L. and Lepas fascicularis E. et S.  Oikos 4: 112-117.


So the "mystery material" we observed attached to the end of the barnacle was actually a float secreted by the cement glands in the barnacle's stalk.  Those floats are visible in the aquarium photos above, and here's a close-up taken under a microscope.  You can see the bubbles!



Along with this remarkable float, the other striking characteristic of these barnacles was their intense blue color.  Here are two views of the cirri, or thoracic appendages, that the barnacle uses to feed.  



The blue color is apparently derived from their food (e.g., copepods).


I'm afraid I don't know how often Blue Buoy Barnacles appear on Northern California beaches.  This is the first time we've seen them during the past 10 years.  Most of the barnacles we saw were attached to By-the-wind Sailors, so it's possible their occurrence could be related to significant strandings of Velella velella (as we've had this summer).  I'm also wondering if the barnacles are more often associated with warmer water?

It's amazing to think about these bright blue barnacles drifting along in the open ocean hanging down from their self-made buoys!


Friday, August 29, 2014

Jughandling

Do you recognize the animal below in its distinctive position at sea?


Sometimes the front flipper is also held downward in an arc towards the hindflipper, leading to a classic shape and an informal term for this behavior — "jughandling."  The next picture will reveal more of the animal.


Note the small head and snout, prominent whiskers, and long ear flaps.  The image above also emphasizes the impressive length of the flippers (and note that the flippers lack fur).

This is a Northern Fur Seal (Callorhinus ursinus), photographed in Monterey Bay on 22 August 2014.  They can also be found offshore of Bodega Head on trips to Cordell Bank.

Northern Fur Seals spend up to 300 days of the year at sea, coming to shore only during the pupping season.  The reason for the jughandling position is unknown.  A thermoregulatory function has been proposed, e.g., in cold water, removing the flippers from the water may prevent heat loss; or in warm water, it may allow heat dissipation.  Other possible explanations for the behavior have involved creating a stable position for sleeping and generating a silhouette that's less conspicuous to predators from below.

Here are two more pictures so you can appreciate this pinniped and ponder this behavior: 



P.S.  Jughandling facts and ideas from Liwanag, H.E.M.  2010.  Energetic costs and thermoregulation in Northern Fur Seal (Callorhinus ursinus) pups: The importance of behavioral strategies for thermal balance in furred marine mammals.  Physiological and Biochemical Zoology 83: 898-91.  

Thursday, August 28, 2014

Scratched on the surface


Risso's Dolphin, or Grampus (Grampus griseus), photographed in Monterey Bay on 22 August 2014.

This is one of the largest dolphins in our area, often reaching a length of 10 feet.  Note the distinctive colorationpale gray, with abundant scratches and scarring (see below).  The marks are probably from other dolphins, or possibly from their prey (such as squid).


The photo above also shows the tall, falcate-shaped dorsal fins.

Risso's Dolphins are most often observed offshore.  However, they have been seen from Bodega Head, with a recent sighting just a few weeks ago.  They primarily eat squid, so they might be following prey inshore.


Keep an eye out for Risso's Dolphins.  If you see a larger group, they might display some interesting behaviors, including spyhopping (as in the photo below) or lobtailing.

Wednesday, August 27, 2014

On smooth gray seas


Scripps's Murrelet (Synthliboramphus scrippsi, formerly a subspecies of Xantus's Murrelet), photographed in Monterey Bay on 22 August 2014.

Scripps's Murrelets breed on islands and offshore rocks from southern California to central Baja California, then disperse northward after the nesting season.

During the non-breeding season, the highest numbers are observed between Point Conception and Monterey Bay/Point Año Nuevo, and from about 20-100 km offshore.

Here's a slightly different angle of this handsome alcid:


Eric asked me if the name had anything to do with the Scripps Institution of Oceanography (SIO).  This was a bit of an etymological adventure.  First I had to find the paper in which the scrippsi subspecies of Xantus's Murrelet was originally described in 1939 to see if it mentioned how they came up with the name.  Here's what it said: 

"This bird and two others were secured while the authors were on a collecting trip on the yacht of the late Robert P. Scripps of San Diego. It seems fitting that we should name the new form in honor of this man who did so much to further interest in Pacific coast science..."

Okay, so was Robert P. Scripps the same person that the SIO is named after?  I did an Internet search for his name and came up with this story about a Robert P. Scripps who died in 2012 (see link below).  He was the grandson of E.W. Scripps who was the co-founder of the Institution.


But note that the article describing the scrippsi subspecies of Xantus's Murrelet published in 1939 said "the late" Robert P. Scripps.  So I think that this murrelet was named after E.W. Scripps's son, the father of the Robert P. Scripps highlighted in this recent story.  Whew!

Now that that's settled, I'm including two more pictures, just for fun.  I was drawn to the views of this small seabird on such smooth gray seas.



And how the murrelet would disappear below the surface with a flick of the wings:


P.S.  References used for facts above included (1) The Birds of North America account for Scripps's Murrelet by Drost and Lewis (1995) and (2) Green, J.E. and L.W. Arnold.  1939.  An unrecognized race of murrelet on the Pacific coast of North America.  Condor 41: 25-29.

Tuesday, August 26, 2014

Diamonds in the drift

Last night, on 25 August 2014, I was waiting for someone and decided to pick up some trash on the beach.  I glanced along the water line and noticed something that reminded me of the few times I've seen hail being concentrated in driftlines by the incoming waves:


I bent down for a closer look:


Salps!  Although I've seen other species of salps washing ashore on Bodega Head, I believe this is the first time I've seen Thalia democratica stranding on local beaches.

Here's an image with a ruler for scale (below).  When they're in this chain-like stage, they remind me of diamond bracelets (but note if you try to pick them up, the individuals in the chains separate very easily):


Thalia democratica has a somewhat complicated life cycle.  There are two stages: an aggregate stage (as above) and a solitary stage.  The aggregate stage is sexualeach individual in the chain produces one embryo that will develop into a solitary individual.  The solitary individual is asexual each solitary individual will bud off a chain of aggregates.  This life cycle is illustrated below:

 Example of a salp life cycle modified from Alldredge, A.L. and L.P. Madin. 1982.  Pelagic tunicates: Unique herbivores in the marine plankton.  Bioscience 32: 655-663.


Since observing Thalia democratica on Bodega Head has been rare, I brought a few salps in for documentation.

This is a picture of an aggregate individual under the microscope.  The purplish oval spot at the bottom is called a nucleus and the structure just to the right of the nucleus is a developing embryo (it will become a solitary individual).


The next image shows the posterior end of a full-grown solitary individual.  Note the two long projections (pointing backwards).  There is a developing chain of aggregates wrapped around the gut.


While looking through the specimens, I noticed one that looked different and had me puzzled for a moment.  Most of the individuals were easy to sort into either aggregate forms (rounded or tear-drop shaped) or solitary forms (with two long projections).  Here was a small salp that  looked like it had two little "fists" and two "triangular bumps" at the back end:


When I looked very closely at those little "fists," I realized what I was probably looking at:


I'm not sure what the structure is, but there's something in the little fist that looks funnel-shaped (a bit like Shrek's ears)!  When I saw that, I remembered seeing the same thing in the full-grown solitary individual: 


Above, you can see the "Shrek-like" funnel structures at the base of the two long posterior projections.  Also note the two curved spikes, closer to the top of the picture.  I believe the mystery animal I observed is a very small, juvenile solitary individual, and that eventually the "fists" will become long posterior projections and the triangular bumps will become curved spikes.  Although I've seen Thalia democratica before, I've never encountered such a small solitary individual.

One more note: I checked the seawater temperature after finding these salps.  It was approximately 17.5°C.  I'm wondering if their presence this summer has something to do with the warm water?  I'd love to hear about any other sightings of Thalia democratica.

Sunday, August 24, 2014

Fins and feeding at the surface


Seeing a fin like this out at sea always requires a close look — is it a shark, or something else?

If the fin sculls from side-to-side and occasionally flops over, then it most likely belongs to one of these:


This is an Ocean Sunfish (Mola mola), one of the largest (= heaviest) of the bony fishes.  Although most individuals are ~3-5 feet long and weigh 175-500 pounds, the largest recorded was nearly 9 feet long and tipped the scale at just over 5,000 pounds!  

If you haven't seen one before, Ocean Sunfish might be hard to figure out at first.  Their anatomy is unusual.  The caudal (tail) fin has been reduced to a ruffled flap along the trailing edge, so the fish looks dramatically truncated.

The most noticeable fins are the dorsal and anal fins they're the tallest fins and are used for swimming.  If you're looking for them, the pectoral fins are also visible at times they're short and rounded, located behind the eye.  Here's a picture that shows all of the fins I just mentioned (the sunfish is lying on its side at the surface):


The image above also shows the overall rounded and laterally compressed shape of Ocean Sunfish.  This shape is alluded to in their scientific name"Mola" means "millstone."  

The mouth of an Ocean Sunfish is relatively small (this is a head-on view):


But I mention it because we saw them feeding on By-the-wind-Sailors (Velella velella) last week!  

Below are two pictures in a feeding sequence.  The first shows a sunfish approaching a Velella from below.  In the second, the sunfish has just finished inhaling the Velella.  (Note that it appeared to be using its rounded pectoral fins to steer.)




I'll leave you with one last shot of this wonderful open ocean fish.  Watch for them this year as there seem to be quite a few around, perhaps associated with the warmer ocean water.


All photos from Monterey Bay on 22 August 2014.

Friday, August 22, 2014

Aerial pursuit


Parasitic Jaeger (Stercorarius parasiticus) pursuing a Sabine's Gull (Xema sabini), Monterey Bay, 22 August 2014.