This might be the last post about colors and spider silk (at least for a while). The point where the sun rises along the eastern horizon has shifted to the south. The sun's rays no longer strike the corner of our backyard (where I had been photographing the webs) in the same way .
Here's the last set of images taken on 22 July 2017. The scene is a little different. Instead of an orb web, this was a group of strands against a tree trunk, with some overlapping.
Several days ago, I came across an interesting Bull Kelp (Nereocystis luetkeana) specimen washed up on the beach. Instead of being narrow and ribbon-like, the blades were broad, even approaching oval:
If you've been reading this blog for a while, you might recall that I showed a very broad-bladed Bull Kelp a couple of years ago — see "Seaweed puzzler" from 12 April 2015. That blade was ~16 cm across. I compared that to the description in the Marine Algae of California, which stated that the blades could reach up to 15 cm across.
Well, when I saw this specimen, I wondered if it was even broader. Sure enough, I measured it with the ruler along the edge of my notebook and estimated it was ~22 cm wide.
At the time I couldn't remember how wide the 2015 specimen had been. When I reviewed it, I started to wonder if I had measured incorrectly in the field. Could this specimen really be 6 cm wider than the previous one?
I'm glad I took a picture with my notebook next to the blade. To get a second opinion using the photo, I asked Eric to calculate the width of the blade based on the width of my notebook. He came up with 22.65 cm!
So is this a record-wide Bull Kelp blade? Has anyone found a Bull Kelp specimen with blades wider than 22 cm?
If it looks familiar, I showed a similar animal, but a different species, earlier this month.
This is the phoronid Phoronopsis harmeri (formerly Phoronopsis viridis). Note the long tentacles and the greenish coloration. This species lives on the tidal flats in Bodega Harbor. It's amazing to me that you can just park on the side of the road, walk out onto the mudflats, and find these beautiful animals in shallow pools. (There are only 14 species of phoronids in the world!)
The close-up photo above highlights an interesting feature of phoronids. Can you see the red color in some of the tentacles? Phoronids pump blood (containing hemoglobin) into their tentacles to absorb oxygen from the water, then move the oxygenated blood down into their body below the surface of the mud.
Several years ago, Eric wrote an excellent description of blood circulation in phoronids, accompanied by a very helpful illustration. I highly recommend reading his post called "Ebb and Flow."
Then return to this post and check out some of my favorite phoronid images from 25 July 2017:
Perhaps I'll try to get some video of the blood flowing up and down in the tentacles. Not sure whether my camera can capture that, but I think it's worth a try!
Leather Limpet (Onchidella borealis), crawling across the rock in the mid-intertidal zone on 24 July 2017.
Although this Leather Limpet stands out against the rock, sometimes they're well camouflaged against the background. How many individuals can you find in the image below? (Hint: They might be different colors and different sizes.)
I've circled the Leather Limpets in the next photo:
Last week, Eric's summer students were sorting through some plankton samples collected in Bodega Bay and Bodega Harbor. Rachel spotted something different and took a closer look. We're glad she did, because it turned out to be an interesting hydromedusa:
Meet Hydrocoryne bodegensis! The scientists who first described this species (John Rees, Cadet Hand, and Claudia Mills) named it after Bodega Bay because they collected colonies from one of the Bodega Harbor jetties. It's always fun to become familiar with local species that have "bodega" in their names!
This hydroid also has a polyp stage that grows attached to the substrate. The tiny medusae (their bells are only ~1 mm high) develop among the clubbed tentacles of the polyp and then eventually break away to swim in the water column:
Modified from Rees, J.T., C. Hand, and C. Mills. 1976. The life cycle of Hydrocoryne bodegensis, new species (Coelenterata, Hydrozoa) from California, and a comparison with Hydrocoryne miurensis from Japan. Wasmann Journal of Biology 34: 108-118.
Although I didn't know it at the time, five years ago I photographed what might be this species, with a medusa just about to swim away:
Eric captured a short video of the Hydrocoryne bodegensis medusa, so I'm including a video file below. While watching, note the following:
- 4 long tentacles, with visible (knobby) clusters of nematocysts
- each tentacle ends in a prominent rounded cluster of nematocysts (you can locate the end of each tentacle by looking for these rounded tips)
- a red ocelli (eye spot) at the base of each tentacle
- dramatic extension and contraction of the tentacles (this is likely a feeding strategy, e.g., increasing surface area to increase likelihood of prey capture)
It's been windy lately! This photo was taken yesterday, 20 July 2017, but it could just as easily be a picture from the spring.
North northwest winds were blowing at ~20 mph (~17 knots) in the afternoon.
Water temperatures have been cool recently — in the 10-11°C range. And they've generally been cooler than average during the last few months. To track the trends, you can look at the Bodega Ocean Observing Node site (click on the tab of interest).
While doing a recent beach survey, I noticed this Feather Boa Kelp (Egregia menziesii) washed ashore:
It looked quite young — relatively short overall length, with broad blades, and a small holdfast.
When I looked more closely, I was intrigued by the holdfast:
Can you see that the holdfast is attached to a small pieced of wood?
It might be easier to see this from below:
I wondered about the history of this kelp. Did it start growing on a piece of wood that was lodged in rocks somewhere and then part of the wood broke off and washed ashore? Or is it possible the kelp started growing on a small piece of floating driftwood? Have you noticed Feather Boa Kelp growing on wood before?
P.S. I laughed when I read the description of juvenile Feather Boa Kelp on the California Seaweeds eFlora website. It says they look like lasagna noodles. A fun description of those broad, ripply blades!
Not much time tonight, but I think you can see why I couldn't resist sharing this photo. It's one of my favorites of the year!
If you've been following this blog for a while, you might have seen this species before, but it's been several years. This is Manania gwilliami, a beautiful staurozoan. [Staurozoans are now a separate taxonomic class within the cnidarians. Sometimes they're informally called stalked jellyfish.] It was found locally today in the rocky intertidal zone. We didn't measure it, but estimate it was ~12 mm long.
Here's the entire animal:
This individual had beautiful purple highlights. Check out this close-up of two tentacle clusters:
When looking at the tentacles, I noticed some whitish pads at the base of some of the tentacles. Here's one view:
After doing some research, I learned that these are adhesive pads. It is hypothesized that when the staurozoan releases its pedal disc (the base of the stalk) from the substrate, it sometimes holds on with these pads while it reattaches. Since I haven't been able to find many pictures of these interesting structures, here's one more image. Look for the swollen white areas at the bases of the front three tentacles:
I'm sharing these staurozoan photos with you thanks to Hao Hao, one of Eric's summer students at the marine lab. Her curious eyes spotted it attached to a blade of algae in the intertidal zone. Thanks, Hao Hao!
I've continued to photograph spider web strands in our backyard. I'm so taken by this phenomenon and the amazing color combinations, it's hard not to take a few photos when the conditions are right. It's especially nice in the early morning, when the light is interesting and the air is calm (and the spider webs are still).
These are my favorites from the past two days, although it's hard to choose. See what you think:
The pictures above show highlights on single strands, but sometimes several strands are lit up at once:
And here's one series that shows the same two highlighted areas, just in slightly different positions along the strands:
Whenever I look at these colors, I just shake my head in disbelief. The diversity and beauty is astounding.
With many thanks to the spiders and the sun, for creating such colorful works of art!