Peeking out

  

A beautiful view of the tentacles of an Orange Sea Cucumber (Cucumaria miniata).  You can also see a few of the cucumber's tubefeet closer to the rock.  Photo from Del Norte County in California on 4 April 2026.

With thanks to Eric for a great photo! 

A hint of orange

  

An interesting find today (27 June 2024) -- Pachythyone rubra, a more southern sea cucumber that's more common south of Monterey.  It's been documented in Bodega Bay previously, but only a couple of times.  Note that hints of orange color at either end of the cucumber, and the tubefeet that are scattered across the body rather than in regular rows.

To learn more about Pachythyone rubra, check out the previous post called "Goodbye, Rubra Tuesday" on 5 March 2018.

P.S.  If you happen to come across this species in Sonoma County or farther north, I'd love to hear about it.

Lots of loli!

  

We saw at least 10 species of loli, or sea cucumbers, while snorkeling in Hawai'i.  Eric made this great mosaic before we saw the 10th, so above you can compare 9 different species!  [You can click on the image for a larger version.]

Top left: loli, or White-spotted Sea Cucumber (Actinopyga varians)
Top center: loli, or Teated Sea Cucumber (Holothuria whitmaei)
Top right: kohe lelewa, or Sand Sea Cucumber (Holothuria arenicola)

Middle left:  loli, or Difficult Sea Cucumber (Holothuria difficilis)
Middle center: loli okuhi kuhi, or Black Sea Cucumber (Holothuria atra)
Middle right: loli koko, or Impatient Sea Cucumber (Holothuria impatiens)

Bottom left: weli, or Conspicuous Sea Cucumber (Opheodesoma spectabilis)
Bottom center: weli, or Tahitian Sea Cucumber (Euapta tahitiensis)
Bottom right: loli, or Light-spotted Sea Cucumber (Holothuria hilla)

And the 10th (not pictured) was a loli ka'e, or Stubborn Sea Cucumber (Holothuria pervicax).

Fun to see so many different species of loli!

Two cukes

  

I think we've seen 10 species of sea cucumber in the Sonoma/Marin county area, and over the years I've posted photos of 8 of those, but I haven't shown pictures of a couple of species yet.  

So here are two more — above is the Orange Sea Cucumber (Cucumaria miniata).  As you can see, they often live under rocks or in crevices, but sometimes you can catch a glimpse of their bright orange tentacles. 

Below is a California Sea Cucumber (Apostichopus californicus, formerly Parastichopus californicus).  This species is more common in subtidal areas, but with the very low tides last week, I spotted one in the low intertidal zone:

 

 

Perhaps you're wondering how many sea cucumber species total occur in this area?  I'm guessing the number is around 16-18 species.  So we have a little ways to go to see all of the different sea cucumbers, but we'll keep looking!

Out for a stroll

  

Small white sea cucumbers can be hard to identify.  This one might be a Stiff-footed Sea Cucumber (Eupentacta quinquesemita).  Photographed in northern Sonoma County earlier this month.

Not far from the tree...

During one of our recent intertidal zone surveys, Eric noticed this tiny little orange blob on a rock:

 

Although the blob was only ~2 mm long, Eric's eyes are good enough that he wondered if it might be a very young Scarlet Sea Cucumber (Lissothuria nutriens).  I looked with a hand lens and I thought I could see tube feet, which meant that sea cucumber was a definite possibility.  Then we thought — since Lissothuria broods its young, if the blob is a tiny sea cucumber perhaps the mother is nearby.  You've heard that old expression, "The cucumber never falls far from the tree..."?  [Instead of growing up in the plankton, the embryos develop on the mother's back and then the juvenile sea cucumbers walk away from the mother as smaller versions of her.]

We looked more closely and there she was!  Here's a zoomed out view.  Although Scarlet Sea Cucumbers are red, they hold small bits of seaweed and other debris on their backs, so they can be very hard to see at first.  In the photo below, there's one adult sea cucumber and five juveniles.  This will be tricky, but can you spot them all?

 

Below the sea cucumbers are circled, mom in blue and juveniles in orange:

 

Since this is one of the species we're tracking, we documented them with some microscope photos and yes, a video!

These are beautiful little sea cucumbers, so it's a treat to see them up close:

 

With a ruler for scale (marks are in millimeters):

 

At this stage, the sea cucumbers are almost transparent, so it's a wonderful view of their ossicles.  Look for the shiny plates in the body wall and the tentacles.  (For more info about ossicles, see the post called "Scarlet fire" on 12 February 2017.)

 

 

And as if those pictures weren't enough, Eric captured some amazing video.  Check it out!  [If you can't see the video player in your e-mail, click on the title of the post to go directly to the website.]

Little feet

It's been a while since I've shown a marine invertebrate, so here are a few quick photos of a Scarlet Sea Cucumber (Lissothuria nutriens) that Eric encountered recently.  This is a very small individual — only ~4 mm long!  In the pictures below, keep your eyes open for the shiny plates (or ossicles) visible in the body wall, tube feet, and tentacles.

 

 

One with a ruler for scale (tick marks are in millimeters):

 

A close-up of a few tube feet:

 

And a close-up of the tentacles: 

 

P.S.  I've shared some images of adult Scarlet Sea Cucumbers in the past.  For more information, photos, and a video, see the posts called "Scarlet O'Holothuroid" on 22 January 2015 and "Scarlet fire" on 12 February 2017.

 

Goodbye, Rubra Tuesday

A couple of months ago, Eric noticed this interesting sea cucumber in the rocky intertidal zone.  Its coloration caught his eye.  We've encountered quite a few small white sea cucumbers in this area, but this one had orange at both ends.  (Note, the cucumber was ~16 mm long.  The dark areas are bits of woody debris.)

 

Eric has been trying to document the local sea cucumbers.  Over the years, we've realized there are several species of little white cucumbers that can appear very similar to each other.  So far we've found Eupentacta quinquesemita, Pentamera pediparva, and Pseudocnus lubricus.  When we looked closely, this individual didn't look quite right for any of the aforementioned species.  

Here are a few close-ups taken under a microscope.  Note that the tubefeet are scattered across the body — i.e., they aren't arranged in regular rows.

 

 

Also, this sea cucumber's ossicles (tiny calcified plates embedded in the skin) are dense!

 

We couldn't find this sea cucumber in Phil Lambert's Sea Cucumbers of British Columbia, Southeast Alaska, and Puget Sound (1997).  We also had trouble locating it in the Light and Smith Manual (2007).  We kept trying to identify it via the key.  Most of the characters seemed right for Pachythyone rubra, but the key said this species was red or reddish- orange.  So we decided to look at the ossicles.

Here are a few pictures of the ossicles that Eric photographed under a high-powered microscope:

 

The Light and Smith Manual didn't include an illustration of Pachythyone rubra's ossicles.  But we found a diagram in another publication and it was a perfect match!

 

Ossicles from body wall, including (A) 4-holed buttons; (B) reticulated plates; and (C) supporting tables from tube feet.  Modified from Bergen. M.  1996.  Class Holothuroidea.  In J.A. Blake, P.H. Scott, and A. Lissner (eds). Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and the Western Santa Barbara Channel (Vol. 14, Miscellaneous Taxa, pp. 195-250).  Santa Barbara: Santa Barbara Museum of Natural History.

The ossicles confirm that this species is Pachythyone rubra.  Although the Light and Smith Manual described the adults as red/reddish-orange, perhaps the coloration can vary, especially in juveniles and small individuals?  

This more southern species of sea cucumber primarily occurs from Monterey and south.  It has been found one other time in Bodega Bay (in 1976).  As far as we can tell, Bodega Bay is the northern range limit for Pachythyone rubra.  If you find one north of Bodega Bay, we'd love to hear about it!

P.S.  An interesting side note: Pachythyone rubra is a brooder.  Females brood the embryos within the body cavity and release juveniles when they're ~1-5 mm long.

P.P.S.  If felt good to finally hang a name on this cucumber!

Crossed cups around the Pacific Rim

Okay, remember the mystery photo from last night?  Here's a reminder, with a slightly different view:

 

I'll zoom out a bit so you can see a little more.  And yes, for those of you who were wondering, the sand grains on the tentacles are a clue:

 

Any guesses yet?  When we first found this animal, we didn't know what it was.  We had to step through various options and rule out different groups.

Did you notice that the skin adjacent to the tentacles looks shiny?  Here's an extreme close-up so that you can see what I'm referring to:

 

Those shiny pieces are ossicles — tiny calcified plates.  To help identify this organism, we looked at a few of the ossicles under high magnification (400x):

 

Do you have a guess yet?  Think about a soft-bodied animal with a cluster of branched tentacles at one end and microscopic ossicles embedded in the body wall. 

It'll probably help if I tell you that although this animal doesn't have them, most of this animal's relatives have tube feet. 

Here's another look at those digitate (finger-like) tentacles:

Yes!  It's a sea cucumber!  We hadn't seen this species before.  It's a Sand Sea Cucumber (Paracaudina chilensis).  Amazingly, it's distribution includes the entire Pacific Rim (coastal South America, Central America, North America, China, Japan, Australia, and New Zealand).

As you might guess from the common name, and the pictures, this sea cucumber burrows in the sand.  It ingests large volumes of sand to capture organic material from the sand grains for food (hence the "sticky fingers").

This is what the entire sea cucumber looks like (photo below — note there was debris sticking to the cucumber, but that's likely a result of being in the drift line).  We found it washed up on the beach, and puzzled over it for a while.  With my hand lens I could see the tentacles — that helped because the tentacles didn't look right for a peanut worm or a sea anemone.  

Note the very long posterior end.  This sea cucumber lives upside down in the sand (up to 50 cm deep) — tentacles down, and posterior end up near the surface.

 

The shape of the ossicles helped clinch the identification as Paracaudina chilensis.  Many of them are beautiful three-dimensional "crossed cups."  Compare the ossicle images above with this published figure from a specimen in Australia:

 

Modified from O'Loughlin, P.M., S. Barmos, and D. VandenSpiegel. 2011. The paracaudinid sea cucumbers of Australia and New Zealand (Echinodermata: Holothuroidea: Molpadida: Caudinidae). Memoirs of Museum Victoria 68: 37-65.

 

P.S.  Are you wondering about the extra credit (i.e., the source of the brilliant red coloration in the tentacles)?  Paracaudina chilensis has hemoglobin-filled blood cells (in the body cavity and in the tentacles)!  The hemoglobin is likely an adaptation to living buried down in a low-oxygen environment.

 

Scarlet fire

 

About two years ago, I shared a post about the Scarlet Sea Cucumber, Lissothuria nutriens (see post on 22 January 2015).  At that time, I noted this species was rare in Bodega Bay, but we also wondered if this southern sea cucumber might increase in abundance if sea water temperatures became warmer.  It appears that has happened!

The Scarlet Sea Cucumber reaches its northern range limit in Bodega Bay.  There are some records from Duxbury Reef in Bolinas, but so far we haven't been able to find any records from further north.  (This would be a good time to look for them in northern California!)

Remember that this is a small sea cucumber.  Here's a picture from the rocky intertidal zone with some fingertips for scale.  It shows several Scarlet Sea Cucumbers on the rock — look for three reddish blobs in the center of the picture:

 

When the cucumbers are out of water, their tentacles are retracted.  And note that they cover their bodies with bits of debris.  (Recognizing this "covering" behavior is helpful when searching for these sea cucumbers — it differentiates them from red sponges and sea squirts.)

Here's another example, this time a close-up of a single Scarlet Sea Cucumber:

 

Because this species has been rare in our area, we wanted to be certain about the identification.  So Eric double-checked the ossicles (the calcareous plates inside the body wall, tube feet, and tentacles that help identify different species of sea cucumbers).

Below is a diagram illustrating the different types of ossicles found in Scarlet Sea Cucumbers:

 

Ossicles of Lissothuria nutriens.  (A) Curved supporting plate from tube foot, (B) end plate from tube foot, (C) smaller, hourglass-shaped bodies from dorsal body wall.  Modified from Deichmann, E. (1941).  The Holothuroidea collected by the Velero III during the years 1932 to 1938. Part I. Dendrochirota.  Allan Hancock Pacif. Exped. 8: 61-194.

For comparison, here are a few of the ossicles from one of the local specimens.  You can see that the shapes match the drawings above, confirming the identification:

 

If you get lucky and spot a Scarlet Sea Cucumber in a tidepool, along with the red oblong body you might see the tentacles extended.  Interestingly, the tentacles vary in color from fiery orange to scarlet red:

 

These sea cucumbers feed by catching organic material on their tentacles and then moving it to their mouth in the center of the tentacles.  Eric filmed some of this behavior under a microscope in the lab, and he made a wonderful video clip so that you can see the tentacles in action.  (Also watch for the shiny ossicles embedded in the tentacles and tube feet.)

scarlet_sea_cucumber_sanford from Jackie Sones on Vimeo.

We have counted quite a few Scarlet Sea Cucumbers in the low intertidal zone while conducting surveys this past week.  We're also wondering if the warm ocean temperatures during the last couple of years might have allowed this species to move even further north, beyond Bodega Bay.  We'd be very interested in any Scarlet Sea Cucumber observations in northern California, so let us know if you spot one!

 

Cool as a cucumber

Last night I shared a video of a small sea cucumber (the video is also at the end of this post) and I promised more information about it.

This sea cucumber (Cucumaria pseudocurata) is found in the rocky intertidal zone along our coast.  Recently we encountered quite a few of them nestled in shallow depressions below mats of algae.

In the field, the sea cucumbers look like little brown blobs (maximum size is ~3.5 cm, or ~1.5 inches):

 

As you probably saw in the video, when viewed under a microscope their features are easier to see, including tubefeet (for holding on), tentacles (for gathering food), and large shiny ossicles (for skeletal support):

 

Ossicles are plates made of calcium carbonate.  The shape of the ossicles helps distinguish different species of sea cucumbers.  Below is a selection of ossicles from Cucumaria pseudocurata viewed under very high magnification:

 

You can compare the real thing (above) with a book illustration (below) and look for similarities:

 

Modified from Sea Cucumbers of British Columbia, Southeast Alaska, and Puget Sound (Lambert 1997) 

And here's a wonderful close-up view of the ossicles inside the body wall and a tubefoot:

 

Perhaps you remember that the sea cucumber in last night's video was only ~3 mm long.  Cucumaria pseudocurata is a brooder and a direct developer — females lays eggs in January, males release sperm to fertilize the eggs, the female shields the developing embryos with her body for about a month, and eventually tiny juvenile sea cucumbers are visible among the adults.  

The individual in the video was probably about 3-4 months old.  Here's a still picture with a ruler to help you visualize the size (the marks on the ruler represent millimeters):

 

And in case you missed it, here's the video:

cucumaria_juvenile_sanford from Jackie Sones on Vimeo.

Little one

I haven't posted a video in a little while, so here's a nice one that Eric put together recently.  

The little sea cucumber featured in the video is only ~3 mm long.  Watch for the shiny ossicles in the body wall, tentacles, and tubefeet.  (I'll explain more tomorrow night.)
 
If you can't see the video in the e-mail, click on the title of this post to go to the website.

cucumaria_juvenile_sanford from Jackie Sones on Vimeo.


P.S.  Happy Solstice! 
 

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!

Do you like my spots?

 

A mystery close-up for you.  Above is a highly magnified view.  The next two images show the upper portions of the branched tentacles:

 

 

The following three images provide views of the body.

 

The anterior (front) end, with tentacles retracted:

 

The mid-section: 

 

The posterior (back) end:

 

These pictures serve as an introduction to a wonderful sea cucumber, Pentamera pediparva!

This is a northern species with a reported geographic range of British Columbia to northern California.  We are trying to learn more about this species, but this could be the first record south of Eureka, CA.

Do you remember that sea cucumbers have small, calcified plates called ossicles embedded in their skin?  They're the shiny pieces visible in the first photograph of this post.  The ossicles have very distinctive shapes and are important for species-level identification.

Here's a look at some isolated ossicles from this sea cucumber.  The top photos (blue background) are from the tubefeet, while the bottom photos (gray background) are from the skin.  We were uncertain about the identity of this cucumber until we saw these ossicles and matched them with a diagram:

 

Below is an illustration of Pentamera pediparva ossicles.  Compare their shapes with the photos above:

 

 Modified from Sea Cucumbers of British Columbia, Southeast Alaska and Puget Sound (Lambert 1997). 

We're very excited about the possibility of documenting a new site for this little-known sea cucumber.  Eric discovered it on a low intertidal boulder along the Bodega Bay shoreline on 11 November 2015.

P.S.  Hello to Casey and other sea cucumber enthusiasts!