Outer bands?

 

 

Interesting clouds to the east of Cotati last night (21 August 2023) at sunset.  I think these might have been some of the outer bands of tropical storm Hilary (or at least storm-influenced).

A profound change

  

For Eric’s class this summer, he raised the early life stages (larvae) of the Bat Star (Patiria miniata).  Eggs and sperm from spawning can be mixed in the laboratory to produce fertilized embryos.  Like many marine invertebrates, the fertilized embryos of sea stars develop into a swimming larval stage that looks very different from the adult form.  The photo above shows the larval stage (called a brachiolaria) of the Bat Star about 25 days after fertilization.  This stage uses cilia to swim through the water as it feeds on phytoplankton. 

By about 45 days after fertilization, the juvenile sea star is starting to form at the base of the larval body.  In the photo below, the golden-white dome-like section is the developing juvenile body (called the juvenile rudiment), which is already forming its skeleton (made of shiny calcareous plates called ossicles) and its tube feet (that it will use to crawl on the bottom).  

 

At this point, the larva is ready to make its way back to the rocky shore where it will attach and metamorphose into a juvenile sea star!  Metamorphosis requires profound changes, as the larval arms and larval body (transparent structures in image above) are completely reabsorbed into the juvenile body.

Now for the best part.  Eric was able to capture some microscope video of the bat stars over the course of their development!  In the video below you will see the larvae swimming about at ~25 days (where the pink structure is their stomach), and at ~45 days (with the developing juvenile body clearly visible).  In the final video clips from about 50 days, you will see the metamorphosed juveniles walking along the bottom using their first tube feet.  These new juveniles are very tiny (< 0.5 mm across)!

[If you can't see the video player in your e-mail, click on the title of the post above to watch the video on the NHBH website.]

You can read more about this amazing process of development in Bat Stars in some previous posts, "A new star(t)" on 12 August 2013 and "First steps" on 8 August 2017.

P.S.  Many thanks to Ellie and Christina for spawning the Bat Stars, and to Eric for the great video!

Summer nap

 

 

Mom and pup River Otters (Lontra canadensis) resting in the intertidal zone on 19 August 2023.  You could tell mom was tired — she kept nodding off while the pup was fishing and returning to check in with her.  And then the pup curled up for a nap (that's mom's tail that the pup is resting its chin on).

 

Into the night

  

I know I showed a White-lined Sphinx Moth (Hyles lineata) photo not too long ago (see "Lined up" on 13 August 2023), but that one had washed up on the beach and tonight we had a beautiful moth fly into our house.  Eric caught it and when we went to release it outside it sat on his fingers for a couple of minutes.

I haven't worked with sphinx moths up close, so it was interesting to see their antennae.  Above you can see that the antennae taper towards the outer tips and then are hooked at the very end.  And in the photo below you can see that the antennae are lamellate on the ventral side, with lots of fine divisions:

 

 

This one flew off into the night, but now I want to see another one up close!  Photographed in Cotati on 18 August 2023.

Nectaring at the coast

 

 

Air temperatures reached ~65°F (~18°C) on Bodega Head today.  There was lots of insect activity, including quite a few Painted Lady butterflies (Vanessa cardui) — some nectaring on Coyote Brush (Baccharis pilularis) as in the photo above, others on Seaside Daisy (Erigeron glaucus).

Before the split

  

Always fun to see juvenile Bull Kelp (Nereocystis luetkeana).  This one was photographed a few days ago on 12 August 2023.  The blades haven't quite split apart yet, but you can see where that will happen.

Nestled among the branchlets

 

 

We looked down to see this interesting seaweed on the beach today — Cumagloia andersonii.  It usually doesn't have little white specks on it, so we took a closer look.  Below you can see a hint of what's attached to it:

 

 

These are juvenile pelagic gooseneck barnacles (Lepas sp.).  That means it's likely the seaweed has been drifting offshore for a while (long enough for planktonic barnacles to find it, settle, and start to grow).  Although we often see Lepas attached to drift kelp, I couldn't recall seeing Lepas on Cumagloia before, so took a few documentary photos.  

 

Here's an even closer photo where you can see the barnacles nestled among the branchlets of the seaweed:

 

 

P.S.  Ocean temperatures off Bodega Head have been quite warm this week — up to ~16°C or >60°F.  It'll be interesting to keep an eye on these temperatures during the next couple of months.