Bearded Clover (Trifolium barbigerum), Bodega Head, 19 April 2017
P.S. Check out the interesting color patterns on this clover's leaflets (on the left-hand side of the photo). I'm intrigued by the markings, so I did a quick search into what's known about the patterning. It sounds like they're formally called "anthocyanin leaf markings" and they're known to be linked to certain genes.
I was sorting through some pictures from last spring when I encountered this one:
I said to myself, "Huh...do Two-spotted Keyhole Limpets (Fissurellidea bimaculata, formerly Megatebennus bimaculatus) eat sponges?" It certainly looks like the limpet (relatively small, dark brown shell surrounded by a bright yellow mantle) had been eating the green sponge (Halichondria sp.).
So I read the species account in Intertidal Invertebrates of California which said this:
"This species often occurs on compound ascidians where the color pattern provides good camouflage. In the laboratory, Megatebennus has been observed feeding on compound ascidians, and sponge spicules have been found in the gut of specimens collected in the field."
And then I laughed, because the next photo I found was this one:
The Two-spotted Keyhole Limpet above is in the center — with a dark brownish shell (barely visible) surrounded by a pale yellow mantle. It's flanked by several compound ascidians, and you can see how well camouflaged it is.
The description in the species account by Don Abbott and Gene Haderlie was spot-on!
A distant shot in the rain, but I don't think I've posted a photo of a Greater Yellowlegs (Tringa melanoleuca) before. In our area, Greater Yellowlegs are less common at the coast — I don't encounter them often in Bodega Bay.
In the spring, Greater Yellowlegs are migrating north. According to The Birds of North America, they'll nest in muskeg habitats in central Canada and southern Alaska.
This photo was taken along Valley Ford Road in Petaluma on 16 April 2017.
Camissonia strigulosa, photographed in the Bodega Dunes on 5 April 2017
The genus, Camissonia, is named after Adelbert von Chamisso — a German botanist who joined Otto von Kotzebue aboard the Rurik on a scientific voyage around the world in 1815-1816.
Fun fact: When they visited California, Chamisso collected the California Poppy (Eschscholzia californica) and later named it after another scientist on the voyage, Johann Friedrich Eschscholtz.
The species name, strigulosa, is a reference to the short stiff hairs lying flat against the surface of the plant, some of which are visible on the reddish stem in the lower right corner of the picture (they look like a bit of white frosting).
I found several common names for this wildflower. Which do you like better — Strigose Suncup or Sandy-soil Suncup?
Remember the mystery fossil from last week (see "Long in the tooth" and "A closer look")? Well, we think we might have figured it out! It took some sleuthing, and some help from experts. To review, here's the fossil as we found it on the beach:
Amazingly, we had trouble even identifying what type of organism this might be. For example, suggestions ranged from a walrus tooth, to a rudist (an extinct bivalve), to a barnacle, to a plant.
When we looked under a microscope, we noticed channels on the outer wall:
These eroded channels seemed reminiscent of a barnacle. For comparison, here's a close-up of a wall plate from a local barnacle, Balanus nubilus, that lives in the rocky intertidal zone:
You can see why some people thought this fossil might be a barnacle. But we were confused because we couldn't see any sutures, or divisions between wall plates, which would help confirm the identification as a barnacle. [Many barnacles have 4-6 wall plates that fit together in a circle to form the familiar shell that is shaped like a little volcano.]
We sent the photos to Bill Newman at Scripps, one of the world's foremost barnacle experts. Bill suggested that we had discovered the basis (basal plate) of a fossil barnacle! Since it was only the basis, that would explain why we didn't see individual wall plates.
Here's a local barnacle (see below). Many (but not all) barnacle species have a calcareous basal plate where they are attached to a rock (or other surface). The wall plates sit on top of that base. Most of the time, the basal plate is flat. But note that sometimes the basal plate is elongated upwards and forms a shallow cup. The blue arrow is pointing to the division between the lower basal plate and the upper wall plates.
Now imagine if that basal plate could be elongated a lot more, forming a conical tube (like our fossil!). It's an unusual shape for a barnacle, but it's typical of an extinct barnacle called Tamiosoma gregaria (formerly Balanus gregarius).
We found some older illustrations of Tamiosoma fossils, so here's a comparative view from above — the fossil we found is on the right:
Left-hand illustration from Pilsbry, H. A. 1916. The sessile barnacles (Cirripedia) contained in
the collections of the U.S. National Museum, including a monograph of
the American species. Bulletin of the United States National Museum 93.
Tamiosoma has been found in fossil deposits from central California to Baja. It's thought to have lived in shallow embayments between the early Miocene (16-23 million years ago) through the Pleistocene (2.6 million to 11,700 years ago).
Previous studies suggested that Tamiosoma's very elongate base might have been an adaptation to living in mud where sediment accumulated rapidly. [Fun fact: Tamiosoma means "distributed body" and might refer to its unusual elongate form.]
Although we don't know what Tamiosoma looked like when alive, Eric thought it would be helpful to imagine how this amazing barnacle might have been positioned in the mud. He scanned the fossil basis that we found, and then added wall plates (from a drawing of a Tamiosoma fossil) and cirri (feeding appendages). The barnacles probably attached to small hard objects (e.g., a piece of shell) on the surface of the mudflat, and then continued to grow upward as sediment accumulated around them over time.Sometimes multiple individuals were clustered together. Check out Eric's excellent illustration:
P.S. Many thanks to everyone who contributed to this story, especially Bill Newman, folks on the Fossil Forum, and Karen Whittlesey's thesis on this intriguing barnacle!
P.P.S. The next question — where did the fossil we found come from? Do you know of fossil deposits in the Bodega Bay area?
While conducting a survey on the beach yesterday (31 March 2017), we noticed a Turkey Vulture in the distance. We could tell it was feeding on something, but couldn't tell what it was.
When we got closer, the vulture had flown off, so we went over to look at what had attracted the vulture's attention:
At first I thought it was an electric ray, but there were several characters that didn't seem right. After doing some more research, I believe this is a Thornback Guitarfish (Platyrhinoidis triseriata) — the first I've seen.
It's especially important to note that the caudal fin (at the tip of the tail) is relatively small; the two dorsal fins (on the right side of the photo) are about equal in size; and there are three rows of prominent spines running down its back and along the tail (sorry I don't have better pictures of those!).
Thornback Guitarfish prefer shallow water and sandy or muddy bottoms. They are known to occur as far north as Tomales Bay. Have you seen them in Bodega Bay, or anywhere further north?