A festive fourth

  

Red Sea Urchin (Mesocentrotus franciscanus) from Mendocino County in late May 2026.

 Happy Fourth of July! 

Time for owls

  

Some of you might remember that I sometimes see owls in pieces of sea urchin test.  Here's one perched on a branch of coralline algae.  :)  From 8 June 2024.  Do you see an owl, too?

P.S.  For more "urchin owls," see the post called "Duetting" on 11 March 2013.

New Year's Eve ball drop?

  

Very young Red Sea Urchin (Mesocentrotus franciscanus), about 8 mm across, on 31 December 2024.  Best wishes for 2025!

Tool chest?

  

We had to do some field work in Monterey County yesterday, but we arrived a little early, so had a few minutes to observe a few sea otters while eating lunch in Pacific Grove.  

The first sea otters we saw were actively munching on sea urchins -- above, and next two photos:

 

 

 

But then our attention was drawn to a hard slapping sound, and we turned to see an otter trying to crack open a large mussel against a rock that was balanced on the otter's chest:

 

 

 

Several times we watched this otter dive down, bring up a rock and a mussel (or clump of mussels)...and then use the rock like an anvil -- hammering the mussel against the rock.

 

Sea otters are known to do this, but I hadn't photographed it before, so here are a few more images.  (Tool-use by mammals aside from humans is rare.)  In each picture, look for a rock resting on the otter's chest and a mussel between the otter's paws.
 

 

 

 

 

 

 

 

 

We were reading up on this behavior at the end of the day and came across an interesting research paper about tool use by sea otters just published in May 2024.

 

It turns out that using rocks as tools to access hard-shelled prey might be especially important for female otters in areas where their preferred and easier-to-process prey (e.g., abalone and urchins) aren't as common.  And using the rocks to open hard-shelled prey can prevent tooth damage and give the otters access to an alternative food source that otherwise wouldn't be available by biting alone.

Law et al. 2024. Tool use increases mechanical foraging success and tooth health in southern sea otters (Enhydra lutris nereis).  Science 384: 798-802.

 

Pool of light

  

 Morning light in a tidepool with sea urchins (purple) and sea anemones (green).

ha`uku`uku`ula`ula and unauna

Two fun invertebrates found snorkeling in Poipu today (3 April 2024).  

Above, meet ha`uku`uku`ula`ula, or Red Slate Pencil Urchin (Heterocentrotus mamillatus).

Below, check out this tiger-striped crab — a Cone Shell Hermit Crab (Ciliopagurus strigatus).  (The general Hawaiian name for hermit crab is unauna.)

Fun fact — Eric learned that this crab’s flattened body and legs allow it to live within the shells of cone snails (Conus spp.), which are rarely used by other hermit crab species.

We have been feeling very lucky to spend a little time learning about these amazing animals.

Mahalo to Eric for the great photos!

Cued by a temperature change?

  

Eric was doing an end-of-day check on some tanks in the lab last night and noticed some sea urchins spawning!  Above, a male Purple Sea Urchin (Strongylocentrotus purpuratus) with clouds of sperm being released from the gonopores on the upper surface.  

Looking around, we eventually noticed a few female Purple Sea Urchins releasing eggs (more yellow-orange in color):

 

Our guess is that warmer ocean temperatures during the past couple of days triggered spawning.  There's been a lot of upwelling this year, with water temperatures as low as ~8.8°C (~47°F).  But winds calmed down at the end of the week and temperatures rose to ~12°C (~54°F).

There were also a couple of other echinoderms spawning.  Here's a male Red Sea Urchin (Mesocentrotus franciscanus) releasing sperm:

 

 

 

And a female Ochre Sea Star (Pisaster ochraceus) releasing eggs:

 

 

 

What's that saying, "Spring is in the water"?  ;)

Pawsing for prey?

  

We're working down in Monterey County for a couple of days.  At the end of field work this morning (11 August 2022), a Sea Otter (Enhydra lutris) swam by, diving and coming up with Purple Sea Urchins (Stronglycentrotus purpuratus).  (The otter is holding an urchin between its paws.)

Red end of the spectrum

There's a lot of red in the intertidal zone, along with pinks and oranges and golds at that end of the color spectrum.  Sometimes it's fun to scan across different species to see the color similarities.  Here's a little tour from a recent outing:

 

 Fish eggs

Aldisa sanguinea (nudibranch)

 

Peanut worm (Themiste sp.) tentacles

Clam siphons

 

 

Veiled Chiton (Placiphorella velata) in hunting position

 

Juvenile Red Sea Urchin (Mesocentrotus franciscanus)

Tiny shells and spines

Well, I'm running out of time tonight, but I thought it would be fun to share this photo:

 

While doing intertidal surveys this past weekend, we noticed quite a few Sandcastle Worm (Phragmatopoma californica) tubes that were built primarily out of Foraminifera (informally called "forams") shells and small sea urchin spines.  [Forams are single-celled amoeba-like protists.]

More often, these worm tubes are made of darker colored sand grains (see the post "A close call" for examples of the more typical tubes).  But the tubes we saw this weekend really stood out — beautiful white foram shells cemented together with green and purple urchin spines and skeleton pieces.

I'm not sure if the forams are more common right now for some reason, but the worms sure did a good job at finding them and using them to build their tubes!

Uni for breakfast?

On our way to an intertidal field site this morning, we encountered several sea urchins that looked like this:

Can you guess who was responsible for scavenging these urchins?

Here's some additional evidence:

 

Aha!  Black Oystercatcher tracks! 

Not sure how much the oystercatchers were finding inside the urchins, but they were definitely interested.  Perhaps they encountered some sea urchin roe (uni)?  Here's another example:

 

Hail 2 March

We were driving to work this morning when it started to hail.  I haven't seen hail very often in Bodega Bay, so I was pretty excited.  I asked Eric to pull over so I could take a few pictures.  I tried recording a short video (see below).  And then, since the hail wasn't melting very fast, I went down to the beach to photograph the hail on the sand for the record.  [If you can't see the video below, click on the title of this post to go to the website.]

Hail 2 March 2018 from Jackie Sones on Vimeo.

I think I've only seen this once or twice in the last 10 years or so — hailstones being pushed up into a drift line by the waves:

 

Most of the hailstones were ~4 mm across:

 

Next, here's a series of photos with marine flora and fauna for context.

With coralline algae (bleached by the sun):

 

With snail egg capules:  

 

With a small sea urchin spine:

 

With a springtail (collembolid) on a hailstone (upper left corner)!

 

Little ones

 

While conducting surveys in the rocky intertidal zone this afternoon, we encountered some very small juvenile Purple Sea Urchins (Strongylocentrotus purpuratus).  This one was only ~3 mm across.

 

Tubercles and tube feet

 

Yesterday I took a few close-up photos of a Purple Sea Urchin test (or skeleton).

You can see the rounded and raised tubercles to which the urchin spines are attached:

 

Also noticeable are the podial pores, or the holes from which the tube feet emerge.  

Note that the pores are paired (two are placed side-by-side).  One tube foot emerges from each pair of pores:

 

To provide some context for these anatomical features of the skeleton, here are two images of live urchins (an adult and a juvenile), highlighting the urchin spines and the extensible tube feet:

 

 

Pinks and purples in the low zone

 

Not sure exactly why, but I couldn't resist this view — moving water and reflected light with the pinks of the hydrocoral and the purples of the urchins.

Photographed in the low intertidal zone in northern Sonoma County on 24 February 2017.

Reds among the purples

Red Sea Urchins (Mesocentrotus franciscanus) among Purple Sea Urchins (Strongylocentrotus purpuratus) in tidepools along the Mendocino Coast.  The abundance of red urchins this year is notable.

Photographed in Mendocino County on 10 June 2016.

 

 

Mendocino scenes

A couple of seascapes from the Mendocino coast yesterday (10 June 2016):

 

A breezy morning, with Sea Palms (Postelsia palmaeformis) in the foreground.

 

 

Sea urchins (purple), sea anemones (green), and coralline algae (pink) under water on a vertical wall along a deep surge channel.

Three "seas"

We were doing field work on the Mendocino coast today (10 June 2016).  In between surveys, we documented a few nice invertebrates:

 

It might be tricky, but can you find three different species of echinoderms in the photo above?

There's a Purple Sea Urchin (Strongylocentrotus purpuratus).  Next to the urchin is a Six-armed Sea Star (Leptasterias sp.).  And just below the sea star, looking a bit like a brownish blob, is a sea cucumber — still to be identified...stay tuned!

Recruits

 

 

A beautiful Purple Sea Urchin (Strongylocentrotus purpuratus) recruit, ~3 mm across (photographed under a microscope).  We found four individuals of this size in one Bull Kelp holdfast.  Note the very long, outstretched tubefeet, and the hints of purple in the spines.

In a pinch

The predator approaches from below:

 

The prey reacts:

 

In this case, the predator is a Sunflower Star (Pycnopodia helianthoides) and the prey is a Purple Sea Urchin (Strongylocentrotus purpuratus), photographed on the Mendocino coast on 22 August 2013.  

In the photo above, note that the sea urchin has flattened its spines and extended its pincer-like pedicellariae.  The pedicellariae look like little white stars among the purple spines and tubefeet.  

Although small, the pedicellariae can be very effective deterrents against larger predators such as Sunflower Stars.  The pedicellariae pinch and they contain toxins!  [The toxins in Purple Sea Urchin pedicellariae are not harmful to people.]

The next image shows a better view of the urchin's pedicellariae. 

 

This urchin was in "full defense mode", which made it easy to photograph the exposed pedicellariae.  In these images you can clearly see the three-parted pedicellariae spread wide open, ready to fend off the approaching sea star.  In the still photo below, the pedicellariae look delicate and flower-like, but it's more appropriate to think of them as menacing and dangerous!