Cast ashore

Spring winds pushed some gelatinous animals on shore yesterday.  Here are some examples, shown in order from the animals we encountered most frequently to those that were less common during a walk on Salmon Creek Beach on 19 March 2021:

 

 

Giant Bell Jelly (Scrippsia pacifica)

 

 

 

By-the-wind Sailor (Velella velella) — most of these were small, only ~5-6 mm long

 

 

 

 

Nectophore of the siphonophore, Hippopodius hippopus

 

 

 

 

Comb jelly, or sea gooseberry (Pleurobrachia bachei)

 

 

 

 

Moon jelly (Aurelia sp.)

 

Glowing green

When the winds let up during the summer, sometimes you can find gelatinous animals washed up on the beach — e.g., jellyfish, hydromedusae, siphonophores, ctenophores (also known as comb jellies), and salps.  (I'll show some examples of these animals during the next week.)  

Several days ago I noticed quite a few gelatinous animals, and I was especially curious about some of the comb jellies.  This particular comb jelly (Beroe sp.) doesn't look like much once it ends up on the beach.  It could even just look like a thin patch of slime with a pinkish hue:

 

But if you look closely, you can see long parallel lines running from one end to the other — that's your first clue that it's a comb jelly (rather than a jellyfish).

I was looking at these lines (called comb rows) when I thought I saw some green coloration:

 

In my experience, it's unusual for the comb rows to appear green, so I zoomed in for a closer view:

 

Definitely green!  So what's going on?

Most (but not all) species of comb jellies are bioluminescent.  That means they can emit light via an internal chemical reaction.  Bioluminescence is often more visible in the dark, so I was a little confused about what I was seeing...and I still am.

On this web page about bioluminescence, I read that "there are strong antioxidant properties to luminescent reactions (i.e., they mop up oxygen radicals) so there may be light produced internally during protective reactions."

Could this be what has happening with the comb jellies washed up on the beach?  I'll have to ask around, but I thought you might like to see the photos, and perhaps you have some ideas about the green color in these comb jellies:

 

P.S.  Several years ago I showed pictures of this species of comb jelly swimming.  If you'd like to see those pictures, check out the post called "The Pink Predator — Part 2" from 3 November 2014.

 

Little marbles on the sand

 

 

Comb jellies (ctenophores) have been washing up on local beaches lately.  Perhaps you've seen them?  They look like little glass marbles on the sand.  Each one is ~10-15 mm across.

This species, Pleurobrachia bachei, is often called a Sea Gooseberry.  I've written about them before, but it's been a while.  To see what these comb jellies look like when they're swimming, and to learn more about them in general, check out these posts:

"Sticky side arms" on 15 July 2013 

"A two gooseberry day" on 19 February 2012

The Pink Predator -- Part 2

Last fall I showed you a large pink blob on the beach and told you it was a comb jelly, or ctenophore, called Beroe (review that post here).

Well, at that time I didn't have a chance to show you Beroe in its element — when suspended in the water.

Tonight I noticed at least a dozen Beroe washed up on the beach.  Here's one:

 

In mid-September I found a smaller individual so recently stranded that when I placed it in a bowl of seawater, it immediately started swimming around.  Here's a look at this comb jelly looking more like itself (rather than a deflated mass of jelly on the sand!):

 

Above, you can see the long rows of "combs" (made of fused cilia) that Beroe uses to swim.  There are a total of eight comb rows (not all of them are visible in the picture).  [Comb rows are one of the main features that distinguish comb jellies from jellyfish.]  Below is a close-up of those "combs" as they beat from one end of the comb jelly to the other:

 

Beroe has a very large mouth (remember that it's an active predator that often eats other comb jellies).  The mouth is open on the right side in the image below:

 

Now I can feel better that you've seen the true form of this Pink Predator!

Gelatinous assortment

I always have mixed feelings about finding gelatinous animals washed up on the beach.  They belong in deeper water and it's sad to see them pushed up onto the sand by the surf.  But it's also an opportunity to learn about these animals that we wouldn't otherwise get to see unless we were on a boat or diving under water.  And it's a chance to document which species are present in nearshore waters right now.

Here are a few species washed ashore on Salmon Creek Beach after yesterday's big waves.

Representing the Cnidaria —

 

A large purple Moon Jelly (Aurelia sp.)

and

 

A Giant Bell Jelly (Scrippsia pacifica)

Representing the Ctenophora —

 

A small Sea Gooseberry (Pleurobrachia bachei)

Representing the Mollusca —

 

The gelatinous pseudoconch of the pelagic snail Corolla spectabilis

I've written about all of these species before, so if you'd like to learn more about any of them, click on the appropriate name: Moon Jelly, Giant Bell Jelly, Sea Gooseberry, Corolla spectabilis.

 

Watch your step!

I haven't had a chance to post these pictures.  About a week ago on 3 November 2013, large numbers of ctenophores or comb jellies were washing ashore at Doran Beach.  The densities were much higher than usual.

 

These are Sea Gooseberries (Pleurobrachia bachei).  Various sizes were represented, but most individuals were ~1-1.5 cm across.

Here are two different views from above:

 

 

Although most of the gelatinous animals in these aggregations were comb jellies, every now and then a hydromedusa would appear.  In the image below, look for the individual that's larger with lots of short tentacles around the rim, and small red dots (barely visible) at the base of the tentacles.

 

The hydromedusa is Polyorchis penicillatus.  To see a picture of one swimming in Tomales Bay last November, click here.

I'm not sure exactly why so many comb jellies and hydromedusae were washing ashore, but it may have been related to strong winds.

P.S.  If you're new to the blog and would like to learn more about Sea Gooseberries, review earlier posts from 15 July 2013 and 19 February 2012.

The Pink Predator

Sometimes people ask me how I'm able to come up with something new to post every day.  To be honest, I'm not really sure!  I'm often surprised myself.  

There are days like today when I realize that I don't have a "photo of the day" to post yet, and I'm not sure what I'm going to do.  Then I'll make time for a short walk and find something interesting.  

You're more likely to find something if you're determined to do so...if you're really looking.  But the diversity of habitats on and around Bodega Head also makes it easy.  There's always something to see!

Here's an outer beach find from 19 October 2013:

 

This is a very large comb jelly called Beroe.  For scale, the next picture contains a ruler that shows this individual is about 15 cm (6 inches) long.

 

 

Washed up on the sand, it's difficult to see this animal as it's meant to be, swimming in the ocean.

But at least I can show a close-up of the comb rows.  In the image below, look for the parallel lines running down the body of the comb jelly. 

 

Each line is made up of rows of cilia that the comb jelly uses to swim.  Beroe are fast swimmers — they're predators on other comb jellies!

(To learn more about comb rows, review previous posts about sea gooseberries on 15 July 2013 and 19 February 2012.)

If you're interested in seeing a few photos of what Beroe looks like when alive and swimming, check out this web page from The Jellies Zone. 

Sticky side arms

Last night I mentioned seeing ctenophores (or comb jellies) washing up on the beach.  Tonight I took a closer look at a few of them.  This is how they appeared on the sand.  They ranged in size from about 5 mm to 2 cm long.

 

 

I photographed several individuals in a small aquarium.  In the image below, the light is highlighting the comb rows used for propulsion.  The mouth is at the top.

 

In these individuals the long tentacles were noticeably pink.

 

The tentacles have numerous tentillae that can be extended like a cascading net for capturing prey.  Remember that ctenophores don't have stinging cells (nematocysts) like jellyfish, but instead have sticky cells (colloblasts) for capturing prey by adhesion.

 

The long tentacles can be completely withdrawn within sheaths inside the main body of the ctenophore.  Compare the two pictures below.  They show the same individual — the first with both tentacles extended and the second with the righthand tentacle mostly retracted. 

 

 

If you return to the second photo of this post, you can see the pink tentacles inside the ctenophore.

I think this is Pleurobrachia bachei, the same species we often encounter on local beaches in the winter and spring.  In my experience, it's somewhat unusual to see so many washing ashore in July.

P.S.  Pleurobrachia means "side arm" and refers to the position of the long feeding tentacles.

 

When is a bubble not a bubble?

Although bubbles commonly remain on the surface at the edge of receding waves, in mid-winter it's worth checking closely as some of the bubbles may not be bubbles!

Some of them might be ctenophores, also known as comb jellies.  Compared with beach bubbles, these gelatinous animals are completely spherical, thicker, and when seen well, contain pale lines running from pole to pole.  They'll also hold their shape when you pick them up, like soft, clear marbles.

 

It was interesting to notice how the sunlight glowed around them.  Once I realized they were washing ashore, I started looking for these illuminated orbs on the sand.  

[Note: The type of sand in these photos — fine-grained, with lots of shell material — is a clue to the location = Doran Beach].

 

If you focus carefully, sometimes you can see the pale lines running pole-to-pole, similar to longitude lines (or meridians).  These lines contain parallel rows of "combs" that the comb jelly uses for locomotion.

 

 

This type of comb jelly is sometimes called a sea gooseberry (Pleurobrachia bachei).  Most of these individuals were quite small, less than 10 mm long.  I also found one that was only ~4 mm long.  I placed it next to a larger one for scale.  Can you spot it in the picture below?

 

I first introduced sea gooseberries last February.  Click here to learn more about them and see what they look like when swimming in the water.

Combs and mullets?

On 19 September 2012, we were walking through Woods Hole, MA, and noticed some interesting animals in the water below.

The first was a pretty ctenophore or comb jelly, probably a species of Mnemiopsis (sometimes called a sea walnut).  The individual below was ~4 cm long.  Instead of pulsing like jellyfish, ctenophores use rows of "combs" to move through the water.  The comb rows look a bit like stitches.

 

The ctenophores were mostly transparent, but they had a slight pinkish hue, which was helpful when trying to locate them in the water.  

We were traveling, but had an empty mason jar in the car (thanks to some salsa!), so used the jar to scoop up one ctenophore for a closer view.  Here are a few photos for scale.

 

 

Although this ctenophore is not found in the Pacific Ocean, several other species can be seen near Bodega Head.  I posted about one called a sea gooseberry in February.

While scanning for ctenophores, a small school of fish swam into view.  The fish themselves were ~8 inches long.

 

Many of the fish had flashing blue tails with a dark black line along the posterior edge (see next photo).

 

A few of the fish appeared to have narrower snouts, more golden coloration on the back, and black spots along the sides (see next image).  I'm not sure if this variant was a different species, or a different stage of the same species?

 

We're wondering if the dominant fish is a species of mullet, but we're really not sure, so we're looking for input.  We'd be grateful for any assistance!

A two gooseberry day

Early in the afternoon on 18 February 2012, I photographed this Red-flowering Currant (Ribes sanguineum var. glutinosum) in the Bodega Dunes campground.  This shrub is uncommon on the Bodega Head peninsula, but it's one of the first to start flowering.  Currants are in the Gooseberry Family.

Later the same afternoon we encountered quite a few sea gooseberries (Pleurobrachia bachei) washed up on the beach.  On the sand they look like small transparent marbles or crystal-clear gelatinous spheres.

As I was thinking about these two sightings, I realized I hadn't ever heard why sea gooseberries are called gooseberries.  Doing a quick Internet search I encountered a few diagrams of gooseberry fruit (see below).  There is an amazing resemblance between these fruits and the planktonic marine invertebrate! 

To make this visual comparison easier, I photographed a few sea gooseberries in a small aquarium and under a microscope.

Sea gooseberries are ctenophores (commonly known as comb jellies).  Ctenophores are named for their eight rows of ctenes, or comb plates (fused bands of cilia).  The combs beat in metachronal waves to propel the ctenophore.

 

Sea gooseberries are predators that troll for zooplankton prey with two long tentacles (the genus, Pleurobrachia, means "side arms").  The tentacles contain cells that produce a sticky adhesive which traps the prey, e.g., copepods.  (Unlike jellyfish, ctenophores do not have stinging cells.)

To transfer the prey to the mouth which is opposite the tentacles (see below for circular feature in center of ctenophore), the ctenophore does a somersault and wipes the tentacles along the mouth.

 

Here are a few more photos — a sea gooseberry swimming, a view from below, and a close up of the tentacles.  Notice that the side tentacles (tentilla) can also be extended.