With a pearly luster

  

A quick shot of a fun sea squirt, Cnemidocarpa finmarkiensis.  One description says this species has a "pearly luster," which seemed right to me.  

Photograph from the South Jetty in Bodega Harbor on 24 July 2024.  Good spotting, Eric!

Stranded on shore

 

 

It's been a while since we've seen pyrosomes washing up on local beaches, but Eric photographed this one today, 12 October 2023.  It was ~5 cm long.

 

For an introduction to pyrosomes, see the post called "Fire bodies" on 8 December 2014.

 

P.S. If you happen to see any other pyrosomes washing up, I'd be interested in hearing about your observations!

 

Icicles on the beach?

  

Hmmm...they look a little bit like icicles, don't they?  

Pyrosomes (Pyrosoma atlanticum) have been washing up on local beaches recently.  These were photographed on Bodega Head on 23 December 2021.

For more photos and information about pyrosomes, check out the post called "Fire bodies" from 8 December 2014.

Storm strandings

  

Just a quick photo of several pyrosomes washed up on Salmon Creek Beach tonight (28 October 2021).  

 

It's been a while since we've seen pyrosomes locally, but the storm must have pushed some closer to shore as there were hundreds (or even thousands) of pyrosomes on the beach tonight.  Most were relatively small — ranging from ~1-3 cm long.

 

There was an impressive diversity of offshore gelatinous zooplankton washed up tonight — including the pyrosomes, two types of pteropod, one species of heteropod, two kinds of salps, and one siphonophore.  I'll try to show examples of them during the next day or two.

 

To review an introduction to pyrosomes, check out the post called "Fire bodies" from 8 December 2014.

Tubes and slippers on the beach

I've heard from several people that pyrosomes have been washing ashore on beaches — in Monterey and Bodega Bay, California and in Seaside, Oregon.  We saw some pyrosomes ourselves last night (22 February 2017) on Salmon Creek Beach:

 

We estimated there were over 1,000 pyrosomes washed up along about a 1-km stretch of beach.

Below is a closer view.  You might recall that pyrosomes are a type of pelagic tunicate, related to sea squirts.  [For an introduction to pyrosomes, review the "Fire bodies" post from 8 December 2014.]

 

We encountered a variety of sizes (most of them were on the larger end of this size range):

 

I've received a few questions about how to tell pyrosomes from Corolla spectabilis pseudoconchs.  So for anyone who's been puzzling over either one, here's a side-by-side comparison.  Note the overall shape (oval vs. elongate) and color (clear and transparent vs. pinkish and opaque) and structural differences (slipper-shaped vs. tubular).

 

And if you haven't seen it yet, there's an introduction to Corolla on the "Gelatinous thimble" post on 11 August 2012.

Washed ashore

 

Just a quick note that with this recent storm, many interesting pelagic animals have washed ashore.

Do you remember the pyrosomes from 2014?  Quite a few are appearing on the beaches now.

For a description and more information about pyrosomes, review the post from 8 December 2014.

And stay tuned for more interesting discoveries!

Puzzling pigment and points

 

With so many Velella washing ashore recently, I have been wondering why other pelagic animals haven't appeared also.  I was thinking about it again tonight, when I looked down to see this animal near my feet. 

Do you remember it?  Doug found one that was similar last fall — see the post from 20 November 2014.  At that time I mentioned that I'd never seen this stage of this species, so needless to say, I was very intrigued to encounter it tonight.

Here's a picture with a ruler for scale:

 

This is the solitary stage of a salp (or pelagic tunicate) called Thetys vagina.  You can read more about salps in previous posts (e.g., see the link above).

Tonight I'm going to show two close-ups, because this is what caught my attention while observing the animal:

 

There is a pair of pigmented posterior projections.  I know they look like "horns" at first, but keep in mind that these are trailing off the posterior end.  I looked very hard to find a description and explanation for these projections, but I came up empty.  Why do they have them?  Why are they green (and blue)?  It appears as though a portion of the salp's body extends into the middle of these projections — what is that and what is its function?  Do the projections have something to do with streamlining while swimming?  Are they involved in camouflage/distraction?  What do you think?  Do you have any ideas?

 

And here's another close-up, this time of the middle portion of the salp's body:

 

Did you notice all of the small gelatinous spines?  Why do they have these raised points?  Do they deter predators?  They're so small.  I found one paper that suggested a texture like this, rather than a smooth surface, might cut down on reflections, making it more difficult for predators to see the animals.  Let me know if you have other ideas!

(I've always wondered about the role of surface texture in Corolla spectabilis, too — see pictures from August 2012 and November 2012.) 

Serena's wish

This morning Serena submitted a comment on last night's "Fire bodies" post saying that she had seen pyrosomes in the Channel Islands this summer.  At the time, she also observed a small crustacean living inside the pyrosomes.  I replied that I, too, had noticed a small crustacean inside a few of the pyrosomes washed up on Salmon Creek Beach yesterday.  Serena wrote back that she'd like to see a picture of one...so...here it is!

 

I don't know if this is the same animal that Serena saw, but it does have very large eyes, a feature that she remembered. 

At first I thought this might be an isopod because it looked fairly flattened from top-to-bottom.  However, with more attention, and some research, I'm now thinking this is probably an amphipod.  Although amphipods are often flattened side-to-side, some of the hyperiid amphipods can have a more rounded appearance. 

I didn't have a lot of time, but I also found one reference that listed a few known associates of pyrosomes which mentioned hyperiid amphipods.

For now I'll call it an amphipod, but I'd be very interested in feedback from anyone with more experience.

 

And now for some more imaginative thoughts: 

What is it like for an amphipod to live inside of a pyrosome?  When I saw one, it was positioned such that it appeared to have a view looking out at the world through the transparent tunic of the pyrosome.  It must be quite something to be drifting along inside of a long, jet-propelled cylinder.  Do they see other animals swimming by?  Can they move to different places within the pyrosome, e.g., from side to side or front to back?  What is it like for the amphipod when the pyrosome starts to bioluminesce?  Pyrosome bioluminescence can be triggered by motion.  Can the movement of an amphipod start a bioluminescent wave?

Above I mentioned that Serena remembered the amphipod's large eyes.  While observing them, I tried to come up with a name for their color.  I'll let you look, and then I'll tell you what I came up with below.

 

You're going to laugh at me, but eventually I decided on "marsala"— the 2015 Pantone Color of the Year!

What?  You hadn't heard about the color of the year yet?  Well then, you'll have to check it out here at the Pantone web site and see if you think it's a match for this amphipod's trendy eye color.

"Fire bodies"

This morning Alex asked us about a mystery animal he had observed on Salmon Creek Beach.  He described it as gelatinous, long and finger-like, and covered with short spikes.  I've spent many years listening to people describe different types of animals and trying to assist with identifications.  I like this game.  My mind immediately starts working on the puzzle.  This time, as I listened to Alex, I wasn't coming up with an answer.

He told me where he had found them and it wasn't far away.  When I got there, it was easy to spot them.  This is what I saw:

 

They varied in size from about 1 cm to 11 cm long.  The one below was about 4 cm (1.5 inches) long:

 

Here's one of the larger individuals in my hand:

 

We had to look at them under the microscope to confirm the identification.

This is a pyrosome, probably Pyrosoma atlanticum.

So now you might be asking, what is a pyrosome?

A pyrosome is a pelagic tunicate, somewhat like a salp.  It's a colony of individual units or zooids embedded in a common gelatinous tunic.  You're seeing the entire animal in these pictures.  It's a rigid cylinder, closed at one end (the rounded end) and open at the other (the "squared" end).

This diagram may help.  It shows the entire colony, how the zooids are positioned along the periphery, and then there's a close-up of an individual zooid:

 

Modified from Invertebrate Zoology, Sixth Edition (Ruppert and Barnes, 1994)

Note that each zooid has two siphons.  The buccal siphon faces out and pulls water in.  The atrial siphon leads to the central cavity.  Once water flows into the large central cavity, it exits via the single large opening at the back end and slowly propels the colony forward.

The gill basket is used for both respiration and filter-feeding.  Below is a view of several zooids under the microscope.  You can see the buccal siphon at the top, the large gill basket, and the endostyle (on the right).  The endostyle produces mucus that lines the gill basket for feeding — and is thought to be the precursor for the vertebrate thyroid gland.  (The red spot is the brain.)

 

Here's another view that allows you to see how the zooids are embedded in the tunic, and it's really just their siphons that extend above the surface:

 

I don't know how often pyrosomes are seen in this area.  This is the first time I've seen them since moving here (10 years ago).  If you've observed them before, I'd love to hear about it.

Here's another interesting fact about pyrosomes.  Pyrosome comes from "pyro" for "fire" and "soma" for body = "fire body."  The name derives from their amazing bioluminescence.  

After we read about this, we took a quick look at them later in the evening.  Sometimes there would be scattered bright flashes, but when Eric picked one up it was so bright and sustained that it looked like a glow stick!

I'm so thankful that Alex noticed these mystery animals on the beach and pursued his curiosity to ask us about their identity.  I had no idea when I woke up this morning that I'd be documenting a pelagic invertebrate that I'd never seen before!

Wide mouth and ribbon-like muscles

Sometimes when you discover gelatinous bits washed up on the beach, it's hard to tell what animals they came from.  But other times, if you take a closer look at those mysterious bits of transparent "jelly," you might find structures that provide more clues.

Here are a few photos of a gelatinous animal we found washed up on Salmon Creek Beach on 23 March 2013.  It was roughly cylindrical and ~3 cm long. 

 

Under the microscope the dramatic ribbon-like muscle bands encircling the animal were quite prominent.

In the photo above, note the wide mouth near the top of the photo (see close-up below).

 

And the small reddish spot at the bottom of the "V" below the mouth.  I'm not 100% certain, but I think this is the brain/eye of this animal (again, see close-up in next image).

 

At the posterior or tail end, there was a pointed projection and a pale mass which is probably the gut.  Here are two slightly different views.

 

 

This is a type of pelagic tunicate called a salp.  Salps are much more common offshore.  They don't often wash up on beaches unless there are strong onshore winds.

Many of them are very strong swimmers, hence the well developed muscle bands.  The large slit-like mouth is the equivalent of a siphon.  It takes in water which, after passing through the body, is released out the back end.  This water current is used for jet propulsion, gas exchange, and feeding.  As the water flows through the barrel-shaped body, food is captured in sheets of mucous and ingested.

I don't have a lot of experience identifying local salps, but I think this could be Iasis zonaria.  I'll be sending out the photos for confirmation.

If you are having trouble envisioning the animal with all of these parts, here's a basic illustration with labels:

 

Modified from The Biology of Pelagic Tunicates (Bone 1998)

 

Reproduction in salps is somewhat complicated.  They alternate between a solitary form and an aggregate (or chain) form, and one form produces the other.  The solitary form reproduces asexually and releases a long chain of aggregates.  The aggregate form reproduces sexually; each aggregate form produces one (or a few) solitary individuals.

Earlier in March we found a solitary individual that was producing a chain.  I'm not sure if this is the same species as the one pictured above.  It's possible, but either way, it's still worth showing you what a salp chain looks like.  I hope you can make out that there are lots of tiny individuals all lined up next to each other.  If this salp hadn't washed up on the beach, eventually the chain would have been released and would have been free swimming in the ocean.

 

This seems to be a good time of year to find gelatinous animals on local beaches.  I'll feature a few more during the next few days.