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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!


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!