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Friday, October 31, 2014

Offshore bank


Offshore fog bank, 30 October 2014

Thursday, October 30, 2014

October colors


A couple of weeks ago, Jason and Matt mentioned they'd been seeing these nudibranchs at the Spud Point Marina docks.  I've been saving the pictures because they seemed perfect for Halloween!

This is Polycera atra.  I've seen it called a Black Dorid, or an Orange-spike Polycera.  (Halloween Nudibranch wouldn't be such a bad name either!)

Although there is a consistent color theme, individuals are variable.  In contrast to the first individual, others are quite dark see below:


The combination of black and white longitudinal stripes with yellow-orange spots is quite striking.  The next image is a close-up of one individual's head, showing the frontal veil with spiky processes and two spiraled rhinophores (sensory organs) extending upward.

 
Polycera atra feeds on Bugula, a common bryozoan growing on the docks.  Although the nudibranchs can blend in with their dark bryozoan prey, their eggs ribbons are bright white.  The easiest way to find the nudibranchs was to look for the egg ribbons and then to search for a nudibranch nearby.  [These nudibranchs were about 2 cm (3/4 inch) long.]


Happy Halloween!

Wednesday, October 29, 2014

Wedge-shaped


Common Raven (Corvus corvax) off Bodega Head, 24 October 2014

The wedge-shaped tail stands out in this classic silhouette.

Tuesday, October 28, 2014

Not quite the end

On 19 October 2014, I wondered if we'd seen the last of the live By-the-wind Sailors (Velella velella) washing ashore in 2014.  Well, I don't know if anyone else has seen others since then, but Eric and I spotted three individuals on Salmon Creek Beach on 27 October 2014.

All three were very small10, 12, and 15 mm long.  Here's one example:


Bieri (1977) proposed a growth rate for Velella of ~0.5 mm per day.  If this estimate is accurate, these individuals could be ~20-30 days old, and it's possible they're the offspring of the adults that were visible in late summer/early fall. 

So it's not quite the end of the 2014 Velella strandings yet.  Let me know if you see others washed ashore (or floating at sea)!

Monday, October 27, 2014

Elegant lines

 
After visiting the Bolinas Museum (exhibits on nudibranchs and plastic debris in the ocean) and Keith Hansen's Wildlife Gallery & Studio this weekend, we made a quick stop to admire these Northern Pintails (Anas acuta) along the shoreline of Bolinas Lagoon. 

The Birds of North America account says that pintails are ducks of "slender, elegant lines..." and it's easy to see why.

Sunday, October 26, 2014

From the south

One of the strangest things about keeping a blog is that I don't really know who's reading it or what they think of it.  It's always helpful to me to get feedback about the types of posts that people enjoy.  Recently Claudia mentioned that she liked "the blobs" on the beach.  So here's one of my favorite blobs from this summer/fall that I haven't had a chance to post yet.

These clear, gelatinous "blobs" were most often washed up singly (as below).  They were about 3 cm (a little over an inch) long.



Rarely, I found two still attached:


You probably noticed that these animals actually have a recognizable shapewith a distinct point at one end, and a wider base at the opposite end.

Although they get a little "beat up" after going through the surf zone and being tossed onto the beach (their normal habitat is the open ocean), the rest of the animal is much easier to see when placed in a small aquarium (see below).

The "pointed blob" I showed above is the swimming bell (or nectophore) of a siphonophore called Diphyes dispar.  Although not visible on the beach, in the aquarium you can see the siphonophore's tentacles.  The tentacles can be retracted inside the bell, or extended for feeding.  Compare the two photos below (this is the same individual).




Ernst Haeckel illustrated Diphyes dispar in 1888:

From: Haeckel, E. 1888. Report on the Siphonophorae - Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-76, Zoology 28: 1-380.


Why was this one of my favorite "blobs" from this summer/fall?  

Well, first of all, I just love siphonophores.  If you need an introduction to them, or a review, see the posts from 23 January 2012 and 3 April 2013.

Second:  Siphonophores are challenging to identify, but I figured this one out and then received confirmation from Phil Pugh (Thanks, Phil!).  I almost second-guessed myself, because this species is not known to be common in northern California, but the teeth at the base of the nectophore are distinctive (see microscope image below):


Third: As mentioned, Diphyes dispar is a southern species.  The Light and Smith Manual (2007) says that it is, "More likely to be encountered in the southern range of this book [Point Conception], continuing down Baja California, but has worldwide distribution in warmer waters."  It's rare for this siphonophore to be in northern California, and I will always remember it as a symbol of the warm water event we experienced in 2014.

Saturday, October 25, 2014

Seeing spots

I looked through the microscope and all I saw was spots.  Bright orange spots!


I've seen lots of snail larvae, formally known as veligers, but I'd never seen one with orange spots on its velum!

Here's a closer view (below).  How many orange spots do you count?


We counted at least 13 spots.  This velum is divided into four large lobes (two on each side).  Three of the four lobes have three spots, while the fourth lobe (in the upper right corner in the photo above) has four spots. 

The next image shows the veliger and spots from a slightly different angle.  Note also the cilia along the edge of the velum.  The cilia beat very quickly to help the veliger swim.



Of course we wanted to know the identity of such an intriguing veliger.  However, we couldn't find a match in the Larval Marine Invertebrates of the Pacific Northwest or by doing quick searches online.  We have been narrowing down a possible identity in a somewhat unusual way.  

When I searched for "veliger with orange spots on velum," Google showed us a small portion of text from a book with a description that seemed to match but for which we couldn't see the species name.  Eric kept working on it and eventually figured out that the text was probably referring to a British snail known as Mangelia nebula.  Then he found a paper that described the eggs and larvae of the family of snails (the Turridae) that included this species.  The veligers of some British turrid snails (e.g., see Mangelia nebula below) look very similar to our mystery animal, with spotted velar lobes:


Modified from Lebour, M.V. 1934. The eggs and larvae of some British Turridae. Journal of the Marine Biological Association of the United Kingdom 19: 541-558 


So although we don't know for sure, our best guess right now is that this wonderful polka-dotted veliger could be some type of turrid snail.  [There are a number of turrid snails in California, so we're contacting experts to find out if this veliger could be a match for one of them.] 

To help with the identification, we also tried to get pictures of the snail's shell: 



Why does this veliger have such bright orange spots?  You might think that the orange would make it more visible to predators.  Could the spots be distracting?  Could they draw attention to the edge of the velum, rather than the shell?  Could they somehow look like surrounding particles in the water and help to camouflage the veliger?  Can you think of other reasons it might be valuable for a larval snail to have orange spots?



See below for a short video clip of this tiny snail veliger swimming:


Thursday, October 23, 2014

Not ribbon candy!


This is a little out of order, but I didn't have a chance to share this picture last week.  Do you recognize this shrub?  

I wish we had manzanita growing on Bodega Head.  This picture was taken in Yosemite.  

The red and copper-colored bark is so appealing [a-peel-ing? ;) ]!  Not having spent a lot of time studying California shrubs, it's easy to start asking questions about manzanita bark.  Why is it so red?  Why does it peel?  Why is it so smooth underneath?  I wondered if there would be something protective about these features.  

Sure enough, when I looked for a quick answer on the Internet, I found a Bay Nature article entitled, Why is manzanita bark so smooth and red?  It's worth reading, but the basic idea is that the peeling bark may help prevent things from growing on the trunk/stems...and the red color is an indicator of tannins, chemicals which taste bitter and thereby reduce herbivory.

It's the total opposite of ribbon candy, which is what these beautiful shimmery peels reminded me of when I first saw them.  Perhaps that dates me somewhat, as ribbon candy doesn't seem to be as common anymore.  It used to be shared during holiday events when I was young.

Wednesday, October 22, 2014

Tuesday, October 21, 2014

Shake it, shake it

Tonight I feel very fortunate that I get to introduce you to such a charismatic invertebrate.  Some of you are probably familiar with spoon worms, a group that includes innkeeper worms (Urechis caupo).  If you studied marine biology on the West Coast, it's likely you learned about them in class or saw them in their U-shaped burrows on a tidal flat.  If you're a fisherman, you might harvest them for bait.  If you aren't yet familiar with spoon worms, don't worry!  I'll write about the adults in the future.  

But a couple of weeks ago, we encountered our very first larval spoon worm!  And I'm guessing many of you, even if you're familiar with the adults, have never seen the larval form of these fascinating marine worms.

So here you go a spoon worm trochophore!  (It's ~1.6 mm long.)


The diagram below illustrates some of its major features: 

Modified from A Guide to Marine Coastal Plankton and Marine Invertebrate Larvae (Second Edition) by Smith and Johnson (1996)

  • The prototroch and telotroch are ciliary bandsthey are very active and aid in swimming.  
  • We're pointing out the location of the mouth, but it's not easy to see in either the images or the video (now you know what's coming!).  
  • The epidermal rings are quite noticeable, but note that they are not true body segments.  Unlike polychaete worms, spoon worms are unsegmented.
  • The bonellin pigment spots are special.  Their green color is distinctive and they're unique to spoon worms (although not all spoon worms have them)!  The mysteries of bonellin are still being studied, but it's thought that it might act as a toxin, an antibiotic, and that in some cases it's involved with sex determination.

Spoon worms have an impressive hydrostatic skeleton muscles in the body wall work against internal fluid — which means the whole body is involved in dramatic waves of peristaltic contractions.

You can see this in the amazing diversity of shapes in pictures of the larva taken only seconds apartsee sequence below:





You can appreciate this even more by observing the spoon worm larva in action!  Watch for a few things in this video: The whirling ciliary bands, the waves of contraction, the green bonellin pigment spots...and then after the larva undergoes metamorphosis into a juvenile worm, look for 2 setae (bristles) in the mid-section and the formation of the proboscis (the spoon!) at the tip.  (Then keep reading for one more highlight.)



Okay,  I know that video was fun, but this one is even better.  I'm guessing many of you have been waiting for the latest music video from Spineless Studios.  Don't miss this one!  You'll never see spoon worms the same way again!

http://www.youtube.com/watch?v=gv4RQQkhRaA 


P.S.  Many thanks to Carol for sharing her plankton sample that included this wonderful larval spoon worm!

P.P.S.  For anyone who's wondering, we think this is Listriolobus pelodes, but we're still contacting experts to help confirm the species identification.

Monday, October 20, 2014

What's rarer?

A green flash, or a picture of Snowy Plovers in flight?

Perhaps that's not a fair comparison.  I'm starting to feel like you can see a green flash if you want to, as long as the conditions are right, and you're willing to watch.  Here's one from 20 October 2014 (below).  Eric and I were near the ocean at sunset and thought there was potential for a flash so we lingered until the sun went down.  [You can click on the images for slightly larger versions.]


A minute later (at 6:27 p.m.): 



Most of the time I see Snowy Plovers walking, running, or resting on the sand.  On Saturday I was on the tidal flats in Bodega Harbor during a flood tide.  The wind was calm, so the conditions were excellent for hearing shorebird calls.  Snowy Plovers have a very quiet, subtle call, but I heard this small flock coming from a distance, and I knew I had a rare opportunity to photograph them in flight.  I can do better, but it's a start!




P.S.  I first wrote about green flashes last December you can read that post here.

Sunday, October 19, 2014

The end?

Sometimes we mark the beginnings of events, or the peaks, but we're not as good at documenting the ends.

Large numbers of By-the-wind Sailors washed ashore throughout late July, August, and September.  In late September, around the 28th, after some strong northwest winds, Velella started to become hard to find on local beaches.

As of today (19 October 2014), there are still a few non-living floats/sails washing up, but not many.

Also of note is that smaller Velella started to appear in late August (see below).  These Velella were between ~1.5-3 cm long.



These smaller Velella never became abundant, but became more common through September, and we saw ~10 of them today on Salmon Creek Beach.

Here's one from 27 September...



...and a few non-living floats/sails from 19 October: 



It appears that we've passed the time of seeing live Velella washing ashore in 2014 (but I'd love to hear about it if you see one!).

Saturday, October 18, 2014

Giants and pygmies


The Giant Sequoias (Sequoiadendron giganteum) of the Sierra Nevada are impossible to capture in pictures.  When mature, many trees are 200-300 feet high and 30 feet in diameter.  (The largest trees are over 3,000 years old!)  These images are from the Mariposa Grove on 16 October 2014.

I love the color and texture of the bark:



In contrast to these enormous trees, while walking along a path and enjoying the forest, a small gray bird flew in and landed on a lichen-covered branch.  Can you find it in the picture below?


It's near the center of the photo, just to the right of the trunk.

Do you know what kind of bird it is?  

The next image will give it away.



A Northern Pygmy-Owl (Glaucidium gnoma)!  What a treat to be among some of the largest trees and to see one of the smallest owls!  Northern Pygmy-Owls are only ~6-7 inches long and weigh about 60-70 grams (2-2.5 ounces).  Note the relatively long, barred tail.

And did you notice that the owl had a prey item? 


I wish I could tell what the owl had caught.  It looks like a small mammal, gray in color, and perhaps with soft fur (like a mole or shrew?).  If you have any ideas, let me know!

P.S.  Although you won't find Giant Sequoias near Bodega Head (they only grow in the Sierras), you might find Northern Pygmy-Owls nearby.  They've been observed in the Willow Creek area. 

Friday, October 17, 2014

Peering and probing


Before we left Yosemite yesterday, we went on a short walk in the Mariposa Grove.  Along with the trees (which I'll talk about later), there were a few bird highlights.

I've hardly spent any time in the Sierras, so this was my first time seeing this striking black-and-white woodpecker typically associated with montane forests dominated by pines (especially Ponderosa Pines).

White-headed Woodpeckers (Picoides albolarvatus) are known for their dominantly jet black plumage, although in the right light you could see glossy bluish feathers (similar to ravens):


I read more about this species when I returned to the coast and learned that their diet includes pine seeds and invertebrates.  According to the Birds of North America account, White-headed Woodpeckers often feed on tree trunks that are furrowed or plated (containing lots of fissures).  And these woodpeckers are known for peering and probing, and flaking and gleaning, rather than hammering and boring into the bark.  The following images illustrate the peering and probing behaviors:
 


You probably noticed the small red spot (formally called a nuchal patch) on the back of this individual's head, indicative of a male.  Here's a better view of it:


We actually saw two woodpeckers, and the first was a female, lacking the red nuchal patch.  She was foraging in a place that made her more difficult to photograph, but I think it's still a decent comparison (see below).  Observations suggest that White-headed Woodpecker pairs remain together year-round.


What a way to end our trip — watching White-headed Woodpeckers weave their ways across wide trunks in wondrous woods!

Wednesday, October 15, 2014

Hanging from the branches


We spent most of the day in an indoor meeting (near Wawona), but during a short walk in the late afternoon we spotted this wonderful nest hanging from the branches of a Western Dogwood (Cornus sericia).

We wondered about the white material scattered on the outside of the nest.  Can you tell what it is?

Here's a closer view:


Our best guess is flower petals, perhaps from the dogwood itself.  What do you think?  

I had also wondered if the petals had simply stuck to the nest, or if the bird purposely included them in the nest.  Most of the group felt the bird probably incorporated them into the nest, perhaps for camouflage.

And of course, we're all wondering which species of bird built the nest.  I don't know the answer, but if you do, let me know!