Wind and fog

 

 Wind and fog, Bodega Head, 12 June 2012

P.S.  Congratulations, Dr. Evelyne Kuo!  We're proud of you!

Gentian

 

A beautiful Oregon Gentian (Gentiana affinis var. ovata) photographed in a coastal grassland near Dillon Beach on 11 June 2012.  I love the scattered green spots at the tips of the petals.  Note the sharply triangular points between the petals.  Three cheers for native coastal prairie wildflowers!

In the tube, Part 2

Have you ever found something like this on the beach?

Many people are surprised to learn that this is a cluster of calcareous tubes made by snails.  That's right, it's not a group of worms, but snails that live in tubes permanently attached to the substrate.

These are vermetid gastropods called Petaloconchus montereyensis. Here's what they look like when they're alive.  These specimens are from the low rocky intertidal zone on Bodega Head.  (The following images were taken under a microscope.  Each tube opening is ~2 mm across.) 

 

With an even closer view, you can see the snails inside the tubes.

 

On the right, the brown, saucer-shaped operculum (or trap door) is visible.  On the left, look for the tentacles and the mouth above the operculum.  Below is an even closer view.  Note the bright blue highlights and the dark eye at the base of the uppermost tentacle.

 

There are so many interesting things about Petaloconchus, it's hard to know where to start.  Here are a few amazing attributes:

Possibly unique among gastropods, they periodically shed and replace their operculum.  Here's a close-up of the chitinous operculum (below).  It almost looks like a contact lens (with a spiral in the center) perched on top of the snail's foot.

 

This diagram shows the stages of operculum replacement.

Adapted from Hadfield, M.G.  1970.  Observations on the anatomy and biology of two California vermetid gastropods.  Veliger 12: 301-309.  (Op = operculum)

They produce mucous nets to capture food particles suspended in the water.  Although it may be tough to see, look for the small mucous mass between the tentacles in the photo below (it's at ~ 3 o'clock).

Females brood egg capsules within their tubes and the young hatch as crawl-away juveniles.  Although I'm not sure that the tiny snail below is a juvenile Petaloconchus, they would look similar so it seemed useful to include it as a way to visualize a newly hatched Petaloconchus starting to explore its world and searching for a place to attach to the rock.

 

P.S.  To compare with the somewhat similar looking spirorbid tube worms, see the original "In the tube" post from 6 February 2012.

Plumulaceous barbs

 Any guesses on who this feather belongs to?

 

 Found in Sebastopol on 10 June 2012 

Note the plumulaceous barbs at the base of the feather — the loose, downy parts that are soft and fluffy.  They aid in insulation.

 

Our best guess is Red-shouldered Hawk (Buteo lineatus).  I wish I had better photos of a Red-shouldered Hawk, but here are a couple from our yard in Sebastopol:

 

Note the black tail feathers with distinct white bands.

Can you find the hawk in the photo below?

 

This individual was perched very high in a redwood tree.  Below is a zoomed in view.

 

Red-shouldered Hawks can be seen year-round on Bodega Head, but they are less common than Red-tailed Hawks.

 

Sand wasp

 

 Sand Wasp (Bembix sp.)  

A few photos of a striking wasp from the Bodega Dunes.  [This may be Bembix americana comata, but I don't have any experience identifying this group.]

Most individuals were black and yellow, but some had white stripes instead of yellow (see below).  Note the bright green eyes and dramatic yellow legs.

 

These solitary wasps are found in open sand areas.  Females dig burrows for raising their young.  The female captures and kills a fly, brings it to the burrow, and lays a single egg on the dead fly.  After the larva hatches the female continues to provision the young, bringing food to the developing larva.

Here's a photo of a female actively starting to dig a burrow.  Look for the sand flying backwards.

 

Here's a single burrow entrance.  Several burrows may be located adjacent to each other.

 

I'm not certain, but I think this is an old pupal case in which the larva undergoes metamorphosis into an adult.  I sometimes find these neat capsules on the surface of the sand.  Are they exposed by erosion?  Do predators dig them up?

 

P.S.  For any wasp enthusiasts who haven't already read Wasp Farm by Howard Evans, I highly recommend it!

 

 

Go Green!

 

Short-spined Seastar (Pisaster brevispinus)

Photo taken on Bodega Head, 7 June 2012.  Note the pink coloration.  Each arm of a seastar is called a RAY.

 

Giant Green Anemone (Anthopleura xanthogrammica)

A close-up of the tentacles.  Each tentacle is armed with nematocysts, small harpoon-like structures that can PIERCE the anemone's prey.

 

Sometimes darker sands can appear on Bodega Head beaches.  Among other minerals, they often contain magnetite and GARNET.

 

Bodega Head sunsets may make you think of RA, the Egyptian sun god.

 

What do all of these photos have in common?  

They're all associated with a certain basketball team that's playing Game 7 on Saturday night.

Let's go, Celtics!

(RAY Allen, Paul PIERCE, Kevin GARNETT, RAjon Rondo, and the rest of the team!)

 

Chemical camouflage

 

View from the southern end of Bodega Head, with Bodega Rock offshore and Tomales Point in the far background.  Note the bright green surfgrass (Phyllospadix scouleri) in the foreground.

 

The Surfgrass Limpet (Lottia paleacea) (= Notoacmaea paleacea) is one of the smallest of the West Coast limpets.  They are tall and narrow, up to 10 mm long and about 3 mm wide (no wider than a surfgrass blade).  

Surfgrass Limpets only live on these slender seagrass blades.  They feed on the plant's outer tissue — look for the grazing scars in the photo below (paler section to the right of the limpet).

 

Surfgrass Limpets appear to be chemically defended against predation by seastars.  Debby Carlton studied this relationship on Bodega Head.  Three small gastropods are common in surfgrass beds — Surfgrass Limpet, Chink Snail (Lacuna marmorata), and Carinated Dove Snail (see yesterday's post).

The two snails react strongly to Six-armed Seastars (Leptasterias sp.).  When contacted by a seastar, the Chink Snail waves its tentacles, twists its shell, and drops off the surfgrass blade, all defensive behaviors to avoid the seastar's grasp.  The Carinated Dove Snail flees, but may also bite the seastar.  In contrast, the Surfgrass Limpet clamps down and remains motionless.  Sometimes the seastar even crawls over the limpet and continues on, without capturing it.

Debby proposed that this was an example of chemical camouflage.  She found evidence that the same chemicals (flavonoids) were present in both the surfgrass tissues and in the limpet's shell.  It's possible the non-visual seastar predator does not detect this likeable limpet because it smells like surfgrass!