Storm strandings -- Part 2

Okay, last night I mentioned there were quite a few different types of gelatinous zooplankton washed up on the beach.  Although these "gelatinous bits" can all seem similar at first, the closer you look, the easier it is to tell the different species apart.  It's often helpful to compare side-by-side photos, so here's a parade of plankton for the record:

 

 

Pyrosome (Pyrosoma atlanticum) — see "Fire bodies" from 8 December 2014

 

 

 

 

A salp, possibly Iasis zonaria — see "Wide mouth and ribbon-like muscles" from 29 March 2013

 

 

The swimming bell of a siphonophore, Chelophyes appendiculata — see "Swimming bells" from 3 April 2013

 

 

Part of a heteropod, Carinaria japonica — see "Carinaria -- Part 2" from 7 December 2014

 

 

 

The pseudoconch (false shell) of the pteropod Corolla spectabilis — see "Gelatinous thimble" from 11 August 2012

 

 

Hard to tell at first, but this is a different pteropod, Cliopsis krohni — see "Angel on the sand" from 13 March 2013

This last species can be tricky to identify.  It really does just look like a round blob on the sand.  But note the darker line running through the middle (that's the digestive tract) -- it's a hint that this is more than just a piece of a jellyfish.  These pteropods are delicate (used to being submerged in offshore waters), so they get beat up when they are tumbled in the surf zone and deposited on the sand.  But if you put them in a little bit of water, sometimes their heads (with tentacles) are revealed, as are their "wings" — the foot of a mollusc modified into swimming appendages.  Here's a short video clip so you can see the wings in action.  [If you can't see the video player in the e-mail, click here to see the video.]

Typhoon Songda

During the last two days, we've been feeling the effects of Typhoon Songda — stormy conditions, with strong winds, rain, and big waves.

Yesterday (14 October 2016) we found quite a few heteropods washed up on Salmon Creek Beach.  Here's one of the larger individuals:

 

I haven't encountered Carinaria japonica very often.  I wrote about this fascinating pelagic snail on 7 December 2014, but that was based on a sighting in March 2011.  To review those pictures and more information about Carinaria japonica, click here.

There were some other interesting things washed up on the beach yesterday, so Eric and I started wondering about the direction of the currents — was the flow from the north or the south? 

This morning I remembered to check the current maps on the marine lab's website, and noted the strong flow from the south.

Then I went for a short beach walk this afternoon and found this washed up on the beach:

 

From a distance, I thought it might be a large pine cone.  When I got closer I thought perhaps it was a pineapple.  Then when I was right next to it, I realized what it was — an artichoke!  I smiled and laughed.  :)  Of course!  This confirmed the flow from the south (maybe from Castroville?).  The recent storm represented the "Artichoke Express" rather than the "Pineapple Express"!

P.S.  I'm guessing this will be one of the only (if not the only!) posts that includes both a heteropod and an artichoke!

Carinaria -- Part 2

Last night I shared images of the larval stage of a heteropod called Carinaria japonica.  Alice submitted a comment, mentioning that she had wondered what the adults looked like.

I've only seen the adults once, after a big storm, on 25 March 2011.  I found pieces of them washed up on the beach.  I was puzzled at first, but eventually figured out what they were, with generous help from Roger Seapy. 

Roger has written an excellent description of Carinaria japonica, illustrated with wonderful pictures, at the Tree of Life web site.  I highly recommend his well-written account.

If you'd like to see my pictures from Bodega Head, I'll include those below.  

For orientation, here's a diagram with their basic anatomy:

 

Modified from McGowan, J. A.  1967.  Distributional atlas of pelagic molluscs in the California Current region. CalCOFI Atlas 6: 1-218.

You can see that their shell is very small compared to the rest of the body.  I didn't find any shells in 2011, so I don't have pictures of them. However, in the diagram above we labeled the protoconch, which is the larval shell, because that's what remains of the spiraled larval shell as shown in the post about the veliger last night!

I have nice pictures of pieces of the adult heteropods that include the tail with crest, and the rounded swimming fin — which is dark purple in the photo below.

 

Here's another example, next to a piece of Feather Boa Kelp (Egregia menziesii) for scale (below).  These are large animals — up to 15 cm long.

 

I also have a picture of the proboscis, which is the front end:

 

Inside the proboscis is a radula, or file-like tongue.  Heteropods are active, visual predators.  Carinaria japonica feeds on doliolids, salps, and arrow worms, among other things.  They'll use the radula to rasp at their prey.  Here's a picture of a radula taken under a high power microscope.  Note the dramatic teeth!

 

Although I didn't photograph any entire Carinaria japonica that day, here's the closest image I have to a complete adult (below).  It's amazing to me that the veligers I showed last night, with small whorled shells and 6 long velar lobes, grow up to look like this!  And although it's not a great picture, perhaps it will be useful if you ever encounter an animal like this washed up on the beach. The purple coloration was very distinctive, as were the sweeping lines of the tail.  (Also note that this individual has small tubercles or bumps between the tip of the tail and the swimming fin.)

 

A fascinating pelagic snail that I hope to see again some day!

Long lobes and remarkable grooves

Are you going to be glad you checked into this blog!  It has been quite a year for interesting plankton offshore of Bodega Head, but this has got to be one of the "coolest" larvae that we've ever seen!

 

This is the veliger, or the larval stage, of a heteropod called Carinaria japonica.  It was collected ~1 km off Bodega Head on 1 December 2014.  I introduced heteropods in September (review that post here), but that was a different family (the atlantids).  Now you get to meet Carinaria.  As adults, they're sometimes called "sea elephants."

Here's a basic illustration of what you're seeing:

 

Modified from Heteropoda by Thiriot-Quiévreux (1973).

And now for a few close-ups highlighting some of these features.

The velum (ciliated structure used for swimming and feeding) is divided into 6 velar lobes.  Note that the lobes are extremely long and slender and they have brown pigment patches at their tips (see below).

 

Two black eyes are visible when the veliger is floating with the opening of the shell facing up:

 

The shell itself is beautiful and transparent, with several whorls.  In the next picture, you can also see one tentacle being extended upward.  The operculum ("trap-door") is being held out behind the shell.

 

Believe it or not, they can withdraw those long velar lobes completely into the shell!  Although it's a little hard to tell what's going on in the next picture, you're mostly seeing the shell in the background, the dark tips on the retracted velar lobes, and the operculum at the lower right.

 

And yes, now you can enjoy a video of these Carinaria veligers in action!

You'll see them swimming...and then there are several clips of feeding behaviors.  Watch for food particles moving along the edges of the long velar lobes.

They use long cilia to drive food particles into a food groove where they are moved along by shorter cilia, like a conveyor belt, to the mouth. 

One section of the video highlights a food particle.  Watch it bounce out to the right — it's recaptured and then you can follow it as it moves along the perimeter of velar lobes on its journey towards the mouth.

There's also a "mystery behavior" in the video.  It looks like cleaning behavior, but we're not certain.  See what you think!

heteropod veliger (Carinaria japonica) from Jackie Sones on Vimeo.

Many thanks to Emily for bringing these heteropod veligers to our attention.  We can share them with you because of her.

Isn't it fun to think about these wonderful 6-armed larvae swimming just offshore of Bodega Head!

 

Lights, cilia, action!

 

If you liked learning about the atlantid heteropod last night, perhaps you'll enjoy this, too.  

I didn't mention that the heteropods have a larval stage that looks very different than the adult.  And although I've talked about veligers (the larval stage of most marine snails) before, e.g., see post from 11 September 2014, this veliger is noticeably different.

 

Check out those lobes!  Many veligers have a velum (a lobed, highly ciliated structure surrounding the head that is used for swimming and feeding), but it's unusual for the velum to have 6 lobes.  When we saw this veliger, we knew it was something different right away, just because of the spectacular multi-lobed velum.

Here's a nice diagram of an atlantid heteropod veliger:

 

Modified from Lalli, C.M. and R.W. Gilmer.  1989.  Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks.  Stanford University Press, Stanford, California.

Note that the shell of the veliger is different than the shell of the adult.  It's much more rounded (see below):

 

But just like the adult, the larva can withdraw completely (velum and all) inside the shell: 

 

This veliger was discovered by Emily after a plankton tow off Bodega Head on 9 September 2014.  Eric has kept it alive in the lab since then and we've seen it developing and growing.

Thiriot-Quiévreux (1973) provided a helpful table with three stages of development in an atlantid heteropod.  As development proceeds, the shell, velum, eyes, and foot all become more complex (see below).

 

 Modified from Thiriot-Quiévreux, C. 1973.  Heteropoda.  Oceanogr. Mar. Biol. Ann. Rev.  11: 237-261.

When we first looked at it, the veliger was in Stage II — two of the lobes were much smaller than the others, the eye spots were relatively small and rounded, and the foot wasn't that noticeable.

However, within 9 days, we saw dramatic changes as the veliger transitioned to Stage III.  The smaller lobes grew substantially so that all 6 lobes on the velum are now of equal size.  The eye spots have become more visible and are now teardrop-shaped.  And the foot has grown as it develops into a swimming fin.

Below are two images so you can see the changes in the velum (the growth of the smaller lobes).  And then you'll get to watch a video with the veliger in action!

Velum with two smaller lobes (they look like the thumbs on a pair of mittens):

 

Velum with all 6 lobes of equal size:

 

And here's the highlight video — it shows the atlantid heteropod veliger actively swimming.  Watch for all of the things discussed above — the long cilia beating along the edges of the velum, the rounded shell, and the transition from having 2 smaller lobes to all 6 lobes of equal length.  By the way, this veliger is less than 0.5 mm long, so we're thankful that a microscope video camera can provide such nice views of this tiny whirling wonder!

atlantid_heteropod_veliger_sanford_2014 from Jackie Sones on Vimeo.

 

P.S.  We'd like to thank Jeff Goddard for helping us confirm this as a heteropod veliger.

Say hello to Atlanta!

 

Don't worry if you're not familiar with this animal yet.  They're microscopic, so not easily observed without special equipment.  But they're fascinating, so I'm sure you'll want to learn more about them soon! 

Thanks to Emily, we had our first chance to photograph and film an atlantid heteropod (Atlanta sp.) that was caught in a plankton tow off Bodega Head on 17 September 2014.

Heteropods are pelagic snails.  They spend their entire lives floating and swimming in the open ocean.  You can see several adaptations to a planktonic existence — a mostly transparent body and shell, a foot that's been modified into a swimming fin, large eyes, and a radula (basically a tongue) with sharp teeth for grasping and tearing prey.  Heteropods are active, visual predators.  [Facts from Roger Seapy's excellent introduction to heteropods on the Tree of Life web page.]

Here's the video.  [This is pretty special, as we can't seem to locate many heteropod videos on the Internet.]

atlantid_heteropod_sanford_2014 from Jackie Sones on Vimeo.

The diagram below illustrates the main body parts visible in these pictures and the video.

 

Modified from The Light and Smith Manual (2007)

Note the coiled shell with the unusual keel that extends from the edge of the outermost whorl.  The keel apparently helps stabilize the animal as it swims with back-and-forth undulations of the swimming fin.

The animal can withdraw completely into its shell.  When it does, it can close the aperture (opening) of the shell with its operculum, just like many intertidal snails that you're probably familiar with.

The fin sucker is used to secure prey, e.g., other pelagic gastropods.

The proboscis is extensible, like an elephant's trunk.  It's transparent, so you can see the radula inside — the radula looks a bit like a small zipper.

The eyes are large and dramatic.  Atlantid heteropods are known for interesting eye-scanning movements, which you saw in the video.  Look for the rounded lens (it looks silvery).  It's thought that the eyes can pick up reflected light off stationary objects.

Here's another picture to look for all of these structures:

 

This heteropod was swimming, so it was difficult to photograph.  Below, look for the keel at the lower edge of the shell.  The gill is also visible inside the largest shell whorl.

 

Although many atlantid heteropods are pictured as I've shown them in the first two images, their normal swimming position is with the swimming fin held up towards the surface.  So it's helpful to think about them like this:

 

P.S.  If you need an explanation of the video: There are a few different things going on.  It starts with an overview of the entire animal.  The eye-scanning behavior will be obvious.  A close-up reveals the radula moving inside the proboscis.  Then you'll see the gill and a close-up of the heart pumping.  (Amazing!)  After that, the heteropod extends its proboscis and its tentacles, then swims away.  The video ends with a few more images to help you appreciate this little-known animal. 

P.P.S.  Most atlantid heteropods are found in tropical and subtropical latitudes.  One species, Atlanta californiensis, is found along the West Coast up to British Columbia.  The Light and Smith Manual (2007) says that Atlanta californiensis is abundant is southern California, but we're not certain how common it is in northern California.  We're trying to get help identifying this individual to find out which species it is.