Mystery barbs

 

Northern Rough-winged Swallow (Stelgidopteryx serripennis) 

When I first started working at the Bodega Marine Lab in 2005, I noticed this species nesting in an open pipe in the wall of a small outbuilding.  Amazingly, I think I've seen these swallows using the same pipe every year since!  I'm not sure if it's the same pair, or if it's been several generations of swallows.  (Some swallows have been known to live for 8-11 years, but a shorter lifespan is more typical.)

Note the brown coloration above, white below, and gray/brown wash across the breast and down the sides.

 

Although I've been familiar with this species for many years, I realized tonight that I didn't really know exactly why it was called a "rough-winged" swallow, so I did some research.

The outermost primary (wing feather) is unusual — there are stiffened barbs along the leading edge that make the margin of the wing file-like (the barbs are recurved in males).  Both the genus and species name refer to this character — "Stelgidopteryx" means "scraper wing" and "serripennis" means "saw wing."  According to The Birds of North America account, "The possible adaptive significance of this feature remains a mystery."  (Although it goes on to mention that one possibility may be sound production during courtship or territoriality.)

I wondered if you could see the barbs, so checked a few photos that showed the leading edge of the wing.  The swallow is preening and scratching in the images below.

 

 

I couldn't see the barbs, but it was interesting to learn about them and to look for them.

I hope these beautiful swallows continue to nest locally for many more years to come!

 

Ruler worm?

Okay, I don't know the identity of this worm yet, but it's too interesting not to post a picture, and perhaps someone out there can help with the identification.  Eric and I have seen a few of them recently in the low intertidal zone on Bodega Head.

 

This worm is fairly small, ~4 cm long and only a few millimeters wide.  You can see the metallic silver coloration and the very regular black striping (reminiscent of a ruler!).  Note that both the anterior (head) and posterior (tail) ends are patterned slightly differently than the middle section.

Here are two close-ups of the head end:

 

 

If you have any thoughts about the identification, or just want to join in on praising this worm, feel free to submit a comment!

P.S.  You could also suggest a possible common name for the worm.  Ruler Worm? (for the tick marks)  Piano Worm? (for the resemblance to black-and-white keys)

Seablush

 

Shortspur Seablush or Rosy Plectritis (Plectritis congesta) 

This native annual wildflower is encountered occasionally on grassy hillsides on Bodega Head.  Most of the small, pinkish flowers are found in dense clusters at the tip of the angular stem.  The leaves are fairly broad, often oblong or elliptic in shape, and may clasp the stem. 

The photograph above is from 24 April 2013, but the one below is from 10 May 2006.

 

P.S.  Happy May Day!

Resting among the kelp

Late Sunday afternoon I encountered a few shorebirds roosting among the dried Bull Kelp on Salmon Creek Beach.  The brown coloration of the Whimbrel was an especially good match, making them hard to see at first.  How many can you spot in the picture below?  (If you're not familiar with Whimbrel, they're the large brown shorebirds with the decurved bills.)

 

There are eight Whimbrel in the image above.  Four spread out along the back edge of the kelp, one on the far left, one near the center, and two on the right.  There's another cluster of four in the middle of the kelp, just right of center.  Below I've zoomed in on this group of four so you can see them better.

 

If you scan the photo above closely, you might be able to find two other shorebirds!  There's a smaller sandpiper and a plover.  Can you find them?

I've cropped the picture a little more to help:

 

In the upper right corner there's a Dunlin (with red back and black belly) and a Semipalmated Plover (with black forehead and black neck ring).

The kelp and driftwood on the beach provide important resting sites for these shorebirds as they migrate northward along the coast.

 

A long way to go

A few days ago Chris wrote to report extremely large numbers of crab larvae swimming in Tomales Bay.  Several weeks ago we heard that researchers were catching record high numbers of crab larvae in Bodega Harbor.  Today I saw drift lines of crab larvae molts on Salmon Creek Beach.  So, here we go.  

If you've eaten Dungeness Crab (Cancer magister), or have encountered adult crabs, but haven't yet seen one in the larval stage before, this is what a Dungeness Crab looks like when it's swimming around in the ocean before it undergoes metamorphosis and becomes a juvenile crab that lives on the bottom:

 

This is a Dungeness Crab megalopa.  It's quite large for a larval crab.  In the photo above, the length from the eyes to the base of the prominent rear spine is about 8-10 mm.  At this stage it still has a long, narrow abdomen.  In the photo above, the abdomen is tucked up underneath the body.  But when the crab is swimming, it's extended out behind the crab (see below).

 

And here's a nice close-up:

 

The megalopa is the final larval stage.  When the megalopa molts, it goes through an amazing transformation (like emerging from a magician's hat!) and becomes a juvenile crab:

 

The carapace (back) of this juvenile was only ~1 cm across.  It has a long way to go before becoming legal size.  In this area, a legal size Dungeness Crab is 5.75 inches (14.6 cm) carapace width.  It will take a crab approximately 3.5-4 years to reach that size.

The basic reproductive cycle for Dungeness Crabs looks something like this:

- adults mate during April-September
- females with eggs from November-February
- eggs start hatching in December, peak in March
- larvae spend 3-5 months in the plankton passing through several stages (1 protozoea, 5 zoeal, 1 megalopa)
- metamorphosis to juvenile benthic crabs during April-June
- approximately 1.5 years (11 molts) to sexual maturity (carapace width 10 cm or 4 inches)

 

Rings and a fighter

We saw quite a few species of nudibranchs (sea slugs) at Pacific Grove on 26 April 2013, but unfortunately I only had time to photograph a couple.

Here are two examples: one species that also occurs on Bodega Head, and another species that doesn't but should be watched for as its current northern limit is Duxbury Reef in Bolinas.

 

This is a Ring-spotted Dorid (Diaulula sandiegensis).  The dark, ring-shaped spots on the pale background are distinctive.  The number of spots varies, with northern individuals tending to have more spots.  (Some of the individuals I've encountered on Bodega Head have a yellowish hue.)  Ring-spotted Dorids eat sponges.  Here's one more view in a slightly different position:

 

The next species is one that hasn't been observed on Bodega Head yet.

 

This is a Fighting Phidiana (Phidiana hiltoni, formerly Phidiana pugnax).  Note the very broad oral tentacles with the narrow orange stripe, the rhinophores with orange at the base, and the dense and colorful cerata along the back (black with orange, pink, and white markings).  Fighting Phidianas eat hydroids, but they also attack and consume other nudibranchs, hence their name.  Here's a close-up:

 

Any sightings of Phidiana hiltoni north of Bolinas would represent a range extension and would be of great interest, so if you see this species, take pictures and let us know!

Short spines and blue rings

We spent this morning tidepooling in Pacific Grove, so I'll probably feature some observations from that outing during the next few days.  The low tide was very early, so this post will be simple.

Here are two extreme close-ups to start with:

 

 

Do you have any guesses about what type of animal this is?  

The answer is in the image below.

 

This is a Giant Sea Star (Pisaster giganteus).  This species is found occasionally in the Bodega Head area, especially near the Spud Point Marina and the jetties at the entrance to the harbor.  Although we found these sea stars in the low intertidal zone, they're more common in deeper waters.  

The first two pictures highlighted the short, purple/pink spines surrounded by blue rings.  Spine color is helpful in differentiating juvenile and adult Giant Sea Stars.  Spines are pink/purple in juveniles and white in adults.  The other individual we encountered this morning was an adult (see below).  For scale, the juvenile above was ~12 cm across, while the adult pictured below was more than 15 cm across.