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Tuesday, June 24, 2014

The barnacle-eaters

Here's an intriguing nudibranch photographed on Bodega Head on 15 June 2014:

Yes, those three little brown bumps on the barnacle-covered rock are nudibranchs.  Meet Onchidoris bilamellata.  The white ribbon in the upper right corner of the image is an egg ribbon, probably laid by one or more of the nudibranchs.

Believe it or not, Onchidoris bilamellata is a barnacle-eater!  They feed on acorn barnacles by "sucking out the body contents by means of an oral pumping mechanism" (Morris, Abbott, and Haderlie 1980).

Below is a zoomed in view of the lower two nudibranchs.  You can see that some of the barnacles next to the nudibranchs are empty.  Were they eaten?  Can a living barnacle sense an approaching nudibranch?  Do the barnacles close up tightly to try to prevent entry by the nudibranch?

In 2012, I photographed a larger aggregation of Onchidoris bilamellata.  They were just starting to lay eggs.  It's fun to see the variation in size and coloration.  How many individuals can you find the next picture?


Are you ready?  I've given it my best shot and have labeled the individuals I counted in the next picture.

[I counted 11 nudibranchs when I scanned the image above.]

Looking at Onchidoris bilamellata out of the water doesn't really do it justice.  I don't have great pictures of it underwater yet, but here's one image from 2011 (below).  You can see the two rhinophores (sensory structures) on the left end; the rounded, club-shaped papillae; and the circle of gills on the right end.

Wednesday, June 18, 2014

Mysterious green mass

An interesting and mysterious green egg mass in the low intertidal zone along the rocky shore of Bodega Head:

Here's a closeup view (below):

We weren't certain what type of egg mass this was, i.e., what type of animal had produced it.  A worm?  A snail?  So we brought a tiny piece back to the lab for a look under the microscope.  Here's the first view:

Tbe egg mass was packed with developing larvae!  Can you tell what they are?

A couple of the larvae (veligers) had hatched and were crawling on the outside of the egg mass:

Now you can see that this is a tiny gastropod.  The shell is very tall.  Two black eyespots are visible.

The next image shows a nice view from the side:

We're not sure which species of gastropod this is, but we'll be asking for ideas.  If you know, let us know!      

Monday, June 16, 2014

The low zone -- with labels!

Okay, here you go.  I've labeled some of the animals and algae I discovered in the scene below.  I wouldn't be surprised if you found different things!

Sunday, June 15, 2014

The low zone

This is a very small section of rock from the low intertidal zone on Bodega Head, photographed on 15 June 2014.  

Sometimes it's fun simply to enjoy all of the different colors and patterns and textures.  Other times I like to try to find as many different types of animals and algae as possible in one picture.  Want to try?

I won't reveal the answers tonight, but I'll show this picture again tomorrow, with labels.

Have fun!

(You can click on the image for a slightly larger version.)

Saturday, June 7, 2014

A bite to eat

Just a few quick photos of a bird that caught my attention in Occidental today:

I heard some soft begging calls, and when I looked up to locate the source, I saw this Cliff Swallow (Petrochelidon pyrrhonota) landing at a nest.

In the picture above, note the orange or rust-colored rump.  Below, look for the pale forehead and the dark, cinnamon- or chestnut-colored throat and side of the face.

When the adult left the nest, the reason for its visit was clear:

There were at least two young swallows visible near the opening to the nest.  The adult was likely bringing food to those large, gaping mouths.

The nestlings withdrew, but then I noticed movement to the right:

An older nestling was visible in a second nest adjacent to the first one.

We weren't the only ones looking for a bite to eat in Occidental today!

Wednesday, June 4, 2014

Yellow spectacles

Today I got lucky.  Lucky that Dan found a rare bird nearby (near Owl Canyon).  Lucky that Mike was thoughtful enough to call me.  Lucky that I was at my desk when he did.  Lucky that I had 15 minutes to spare before I had to leave for a meeting.  Lucky that the bird was there when I arrived, and that it appeared in the open and sang loudly before I had to turn around and leave.  Lucky that I got a few pictures and a couple of rough audio recordings.

Here's the bird:

This is a Yellow-throated Vireo (Vireo flavifrons), a species that's primarily found in eastern North America.  It's only the second time a Yellow-throated Vireo has been observed in Sonoma County, and the first time one has been seen on Bodega Head.

Note the yellow throat and yellow "spectacles" around the eye:

At times this bird was singing loudly:

I'm including two audio recordings below.  This is the first time I've recorded a bird singing with my camera.  The quality isn't the best (you can hear some background camera noise), but if you want to listen to examples of a Yellow-throated Vireo singing on Bodega Head, here you go!

ytvi1 by nhbh

ytvi2 by nhbh

P.S.  The individual phrases in the song are written out in various ways, such as ahweeo, eeyay, ayo, away, oweeah, eeoway see if you think they match the sounds above. 

Monday, June 2, 2014

Izzy and Woolly

It started when I noticed a relatively large yellowish moth on the steps:

I let her crawl onto my finger so that I could move her out of harm's way.  The view from the side was impressive!  Look at those colors and overall fuzziness!

Here's a different angle, highlighting the orange-red color at the base of the front legs:

Do you recognize this moth?  It's an Isabella Tiger Moth (Pyrrharctia isabella), photographed in Bodega Bay on 1 June 2014.

If you don't know the moth, I'm guessing you might be familiar with the caterpillar.  As a caterpillar, it's often known as a Woolly Bear or Banded Woolly Bear.  I couldn't locate a picture of my own tonight, but you can see a few here.  The Banded Woolly Bear caterpillar undergoes metamorphosis and becomes this beautiful Isabella Tiger Moth.

[I'll pause here just to say that on the West Coast the common name of the caterpillar is a little confusing in that there is another caterpillar that's also called a Woolly Bear.  I wrote about this briefly in an earlier post on 28 March 2012 which includes a picture of the "other" Woolly Bear.]

I can't resist showing one more image.  Here's looking at you, Izzy!

P.S.  It sounds like "isabella" refers to the moth's color a pale cream-brown or parchment color, according to Wikipedia.