Curved needles

On 5 November, Emily e-mailed that she had found more pteropods, or sea butterflies — and this time it looked like a different species (i.e., not Hyalocylis striata, the pteropod she identified in September).

These animals were from a plankton tow about 24 km (15 miles) off Bodega Head.

 

Emily noticed that the shell was smooth and the wings had a different shape and were of different proportions.

When we looked under high magnification, we could see those characteristics.  We also noticed that the wings had two very intriguing features — something that looked like small "hooks" about halfway along the inside edge of each wing and two oval rough patches in the middle of each wing just below those "hooks."

 

After consulting a few sources, we believe this is Creseis virgula.  We've seen one common name for it — Curved Needle Pteropod. 

I was excited to find an older drawing of this species which matched perfectly with what we were seeing:

 

Modified from Tesch, J.J.  1946.  The Thecosomatous Pteropods. I. The Atlantic.  Dana-Reports, 28, pp. 1-82.

We learned that the "hooks" are wing protrusions and the "rough patches" are ciliated fields.  This pteropod feeds by capturing suspended food particles in a large mucous net.  The ciliated fields aid in hauling in the mucous net.

 

Creseis virgula is a warm-water species.  Although the CalCOFI Atlas for pelagic molluscs (McGowan 1967) shows one record for 37°N, most are from south of Point Conception (approximately 34°N).

Because it was important to document the occurrence of this pteropod in northern California, Eric captured some wonderful video footage and compiled the best clips.  

There are many things to watch for in this video:

- the way Creseis frequently holds its wings far forward

- at about 20 seconds, a food particle moves between the wings towards the mouth

- when a side view is shown, note the slight curvature of the shell

- there's a close-up of the rhythmic mouth movements

- throughout the video, the heart is visible beating about 1/3 of the way up from the tip of the shell

- and one of the last segments is a bonus — it's a veliger, or the larval stage, of this pteropod.  The veliger doesn't have its wings yet, but instead has a velum, a lobed ciliated swimming organ around the opening of its tiny shell.

pteropod_creseis_virgula_sanford_2014 from Jackie Sones on Vimeo.

P.S.  Nearshore ocean temperatures are still quite warm, especially for this time of year — 14-15°C (57-59°F).

 

"the sleeping one"

 

Coming back from field work just after sunset, I was surprised to hear Eric say, "There's a poorwill."  I had to ask again to make sure I heard him correctly.  Sure enough, there was a Common Poorwill (Phalaenoptilus nuttallii) sitting on the trail ahead of us.

I didn't have the right lens on the camera, so I had to make a change as quickly as possible.  And it was very dark, except for the full moon and our headlamps.  I took two pictures before the poorwill flew off.  They're not the best, but since they're my first pictures of this species, and this is one of my favorite families of birds, I decided to go ahead and show them.

 

Common Poorwills are members of the nightjar family which also includes nighthawks and whip-poor-wills.  They're known for their cryptic plumage, and being crepuscular (active near dawn/dusk) or nocturnal (active at night).

Poorwills are one of the smallest nightjars, at only 19-21 cm (7.5-8 inches) long.  They have very large eyes with a tapetum lucidum, a layer that reflects light back to the retina and helps with vision in low light conditions (it's the reason for the glow in these images).

According to the Birds of North America account, the Hopi Indians called Common Poorwills, "Hölchoko" or "the sleeping one."  They were aware of its ability to enter torpor — a state of physical inactivity usually marked by reduced body temperature and metabolic rate.  Poorwills will enter torpor in response to low temperatures or lack of food.  When in a state of torpor, body temperatures as low as 5°C (41°F) have been recorded and oxygen consumption rates may be reduced by over 90%!  

In Sonoma County, Common Poorwills are uncommon during the summer and rare during the winter, so consider yourself lucky if you see one!

Tropical butterflies -- Part 2

On 28 September, I wrote about a pteropod, or sea butterfly, Hyalocylis striata, found near Bodega Canyon.

On 21 October, we were very excited to receive an e-mail from Carol letting us know that she had found another one in a plankton sample from about 1 km off Bodega Head.

It turns out that Carol's specimen was in very good condition.  And because Hyalocylis is rare in northern California, we took some time to document this individual carefully.  We learned a lot along the way!

 

Note the very broad wings.  And that the tip (lower third) of the shell is smooth, lacking striations.  At first we didn't know what this meant, but Eric eventually found a description that led us to understand that the smooth tip of the shell is a protoconch, or larval shell.  Hyalocylis retains its protoconch for a while, but eventually sheds it and then seals the opening with a membrane!  See illustration below:

 

 Modified from van der Spoel, S. and L. Newman.  1990.  Juveniles of the pteropod Hyalocylis striata (Gastropoda, Pteropoda).  Basteria 54: 203-2010.

Van Der Spoel, S. and L. Newman (1990). Juveniles of the pteropod Hyalocylis striata (Gastropoda, Pteropoda). Basteria, 54: 203-210. - See more at: http://australianmuseum.net.au/Publications-1990#sthash.t8AyVi6z.dpuf

Van Der Spoel, S. and L. Newman (1990). Juveniles of the pteropod Hyalocylis striata (Gastropoda, Pteropoda). Basteria, 54: 203-210. - See more at: http://australianmuseum.net.au/Publications-1990#sthash.t8AyVi6z.dpuf

Van Der Spoel, S. and L. Newman (1990). Juveniles of the pteropod Hyalocylis striata (Gastropoda, Pteropoda). Basteria, 54: 203-210. - See more at: http://australianmuseum.net.au/Publications-1990#sthash.t8AyVi6z.dpuf

Here's another view of this juvenile found in October: 

 

Because we don't get a chance to look at pteropods very often, we also zoomed in for a closer view of the head region and the base of the wings:

 

There's a lot to see, and we were curious about all of it!  We've labeled some of the anatomy in the next picture (below).  Our attention was  drawn especially to the two paired circles in the center of the image.  These are statocysts — sense organs that assist with balance and orientation as the pteropod moves through the water.

 

The story doesn't end here because last night, on 4 November, we received another e-mail, this time from Emily saying that she had discovered some more pteropods in a plankton tow offshore of Bodega Head.

When we went to look at them, we found a tiny Hyalocylis — even smaller than the juvenile from October! (see next image):

 

This small shell lacked striations, and all of the other characteristics looked good for Hyalocylis.

To make it easier to appreciate the size differences among these individuals, we put together a composite picture with all three side-by-side.  An explanation — the first two pteropods didn't survive and are now important specimens at the California Academy of Sciences documenting their occurrence in northern California during the 2014 warm-water event.  From top to bottom, the picture below shows the shell of the September adult (note that it's missing its protoconch), the October juvenile, and the November juvenile.  Approximate shell sizes = 4.75 mm, 0.93 mm, and 0.33 mm.

 

It's potentially significant that juveniles have been documented in the plankton here, as it suggests that Hyalocylis was reproducing in California this year.

Okay, I hope you're still with me.  If so, you won't be disappointed.  You're in for a treat, as the next music video from Spineless Studios has been released!  

Click on the link below for wonderful video footage of Hyalocylis striata.  Note that some of the sequences were slowed down to allow observation and appreciation of the swimming behavior.

Video footage of a juvenile sea butterfly (pteropod), Hyalocylis striata

Spinner!

After a short article appeared in the San Jose Mercury News about warm-water species appearing in northern California this year, Mark Kudrav, a naturalist from Pescadero, contacted us to let us know about another interesting species he documented on August 14th: 

 

Eastern Spinner Dolphins (Stenella longirostris orientalis) are subtropical/tropical species, normally found off Baja, California — from about 24°N and south.  Finding one on Pescadero State Beach (at about 37°N) is quite rare, and perhaps associated with the warm water that extended north along the coast this summer/fall.

Mark said that the dolphin was ~6 feet long.  Spinner dolphins are known for their variable color patterns, but the eastern Pacific subspecies is typically dark.

The dorsal fin is relatively small:

 

The beak and teeth are notable.  Spinner dolphins are known for having very long, slender beaks (hence the species name, "longirostris") and a lot of teeth.  There are 45-65 teeth in each jaw, one of the highest tooth counts of any marine mammal!

 

And here's a shot of the flukes and tail stock.  I read that the swelling on the tail stock might be indicative of a male.

 

Many thanks to Mark for sharing this observation and great photos.  Since I'm still new to California, I don't know how often spinner dolphins show up here, but I thought you'd like to know about this visitor from the south. 

P.S.  For this post, I gleaned some facts from a few web pages: OBIS SEAMAP, American Cetacean Society,  and the Convention on Migratory Species.

 

The Pink Predator -- Part 2

Last fall I showed you a large pink blob on the beach and told you it was a comb jelly, or ctenophore, called Beroe (review that post here).

Well, at that time I didn't have a chance to show you Beroe in its element — when suspended in the water.

Tonight I noticed at least a dozen Beroe washed up on the beach.  Here's one:

 

In mid-September I found a smaller individual so recently stranded that when I placed it in a bowl of seawater, it immediately started swimming around.  Here's a look at this comb jelly looking more like itself (rather than a deflated mass of jelly on the sand!):

 

Above, you can see the long rows of "combs" (made of fused cilia) that Beroe uses to swim.  There are a total of eight comb rows (not all of them are visible in the picture).  [Comb rows are one of the main features that distinguish comb jellies from jellyfish.]  Below is a close-up of those "combs" as they beat from one end of the comb jelly to the other:

 

Beroe has a very large mouth (remember that it's an active predator that often eats other comb jellies).  The mouth is open on the right side in the image below:

 

Now I can feel better that you've seen the true form of this Pink Predator!

Surf zone surprise

An early evening walk on Salmon Creek Beach yielded a surprise in the surf zone: 

 

There were at least 6 Cassin's Auklets (Ptycoramphus aleuticus) very close to shore.  The auklets would drift south with the current, sometimes almost wash up onto the beach, then fly back to deeper water and start the process again.

I'm used to seeing Cassin's Auklets offshore, but watching them in the surf zone raised lots of questions.  

 

What drove them there?  Was it the strong winds yesterday?  Were they looking for a place to rest?  Or was there food attracting them to this location?  If so, what type of food?  Cassin's Auklets eat krill, and there could be krill close to the beach, but is there another possibility?  Fish?  I read later that Cassin's Auklets eat Dungeness Crab larvae.  That seems possible for this location, too, but I don't know if there are many crab larvae around right now.

 

I know that Cassin's Auklets live in the open ocean.  I know they must be used to large waves.  But it was still fascinating to watch them maneuver through the breakers and rough conditions close to the beach. 

 

P.S.  Cassin's Auklets are ~23 cm (9 inches) long.

Time to be social

I went out for a quick peak at Bodega Harbor at the end of the day and noticed this flock of birds near Porto Bodega.  How many do you count?  Can you tell what they are?

 

I'll zoom in a little closer.  Even though these are silhouettes, I think you'll be able to see enough characteristics to help you with the identification:

 

Did you notice the relatively short tail (or what sometimes looks like a lack of a tail), the rounded head, and the stout bill?

Here's one individual in slightly better light:

 

I counted thirteen individuals in this flock of Pied-billed Grebes (Podilymbus podiceps) — see first photo.  

I decided to write about Pied-billed Grebes tonight because I don't often see larger flocks of this species, and I thought it would be fun to ask if you've seen large gatherings of Pied-billed Grebes and if so, what's the largest number of individuals you've recorded?

A few fun facts about Pied-billed Grebes:

Males are generally larger than females, and have heavier bills.  If you've noticed subtle size variation among individuals, it could be a difference between males and females.

 

Their stout bills are somewhat unusual for grebes.  The shape is helpful for handling crustaceans (such as crayfish).

Although highly territorial during the breeding season, Pied-billed Grebes are apparently more social during the non-breeding season.

 

Facts above from The Birds of North America account by Muller and Storer (1999).