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Posts tagged ‘mollusc’

Shut the Door!

[Note: Text below has been corrected / edited on January 5th. Corrections are marked in red.]

Marine snails have doors. Freshwater snails do too.

Some tubeworm species have them as well.

Yes they do.

They all make an “operculum”. That means “little lid” in Latin but, I’m sticking with referencing the structure being like a door. 🙂

See the operculum in my photo of an Oregon Triton below? It’s the structure sealing off the entrance to the shell.

Oregon Triton (Fusitriton oregonensis). That’s a Sunflower Star on the left. With that species now being in such trouble, it’s a clue that this photo was taken before the onslaught of Sea Star Wasting Disease.

 

Oregon Tritons are a big marine snail species with a shell up to 15 cm long (and with a range well beyond Oregon ie. known from northern Alaska to northern Mexico, and Japan). You can imagine how, if the snail did not have the operculum, a predator could still get access to the snail in its shell.

Lewis’ Moonsnails are another really big snail. Their shell can be up to 14 cm wide and look at the size of their bodies relative to the shell!

Lewis’ Moonsnail on the prowl (Neverita lewisii).

 

Even though they can release some water from their bodies to become smaller, they clearly need a big opening (aperture) to their shell to get back in.


It’s a space you do not want to leave wide open. Hence, the need for making an operculum to seal that opening.

Operculum from a Lewis’ Moonsnail. Shape, strength and size is perfect to seal off the entrance.

 

For snail species that may be found in the intertidal zone, closing the shell with the operculum not only protects them from potential predation, it also may offer them some protection from drying out. Greg Jensen, author of Beneath Pacific Tides, thankfully offered the following knowledge correcting my previous statement about how useful the operculum might be for this purpose: “Marine snails don’t generally use their operculum to seal the shell at low tide. They snug themselves up tight to a rock with their foot.”

He also shared that land snails, who do NOT have an operculum, avoid drying out by coming out in the cool of night or when it is otherwise damp. Another adaptation is that, when it gets too dry, they glue their shells onto a hard surface, sealed shut with dried mucous to retain moisture.

Not only does the snail make this shell-like structure, it also grows with the individual.  The operculum is attached to snail’s body so when the snail retreats, the door does its job. Not surprisingly, the shape of the operculum is a match for the size and shape of the opening, therefore varying between species. The three photos below show some differences.

Blue Topsnail with operculum (Calliostoma ligatum, shell to 3 cm across). Even really tiny marine snail species like Common Periwinkles have an operculum.

 

Leafy Hornmouth closing up with the operculum visible at the end of the snail’s foot (Ceratostoma foliatum, shell to 10 cm long). There’s a Three-Line Nudibranch on the upper right. 

 

Purple-Ringed Topsnail with opecullum visible (near a Green Urchin). Calliostoma annulatum, shell to 4 cm wide)

 

But what about hermit crab species who use the snails’ shells once they die? Since the operculum was attached to the body of the deceased snails, are the hermit crabs left with a wide open door?  Oh just look at how amazing nature is in making sure they too are protected within the shell. The photo below shows you why so many marine hermit crab species have one claw bigger than the other. The bigger claw seals off the entrance in lieu of the operculum!

Widehand Hermit in the shell of an Oregon Triton. Widehand hermit is Elassochirus tenuimanu.

 

Not all marine hermit crab species have this adaptation. Other options include choosing a smaller shell so you can “shake it off” and run like hell when threatened. It’s called the Taylor Swift strategy. I’m kidding! But let me know if you get the pop star word play.

I also mentioned that some tubeworm species make an operculum. See below. In the centre of the image there is a Red-Trumpet Calcareous Tubeworm (Serpula columbiana to 6.5 cm long).

Red-Trumpet Calcareous Tubeworm in the centre (Serpula columbiana to 6.5 cm long) with two Checkered Hairysnails (Trichotropsis cancellata to 4 cm long).

 

As a tubeworm, the species captures plankton drifting by with its crown (radioles). As the common name indicates, the operculum in this species is trumpet shaped. For the individual in the photo, the operculum is purple with white stripes.

I had initially stated that there’s a really good reason for this species to have the door and you are looking right at it. Those snails are kleptoparasites. “Klepto” as you likely know, means to steal (from ancient Greek). The Checkered Hairysnails use their long mouthparts (the proboscis) to try to suck up the food the worm captures before it gets to the worm’s mouth. HOWEVER, what I also learned from Greg Jensen is that the theft by the Checkered Hariysnails is apparently so stealth, that the tubeworm does NOT respond to their mouthparts by closing its operculum.

Thereby, the operculum may help these tubeworms protect their crown (and other body parts) but does not protect them from kleptoparasites. 

But YOU know what to do.

Unwelcome guests? Shut the door!

All photos ©Jackie Hildering, taken near NE Vancouver Island. 

There are times however where you want the door wide open IF you are a marine snail. The additional photos below include that information.

Oregon Tritons mating. That’s a time when you want opercula out of the way. Unlike may humans, they must mate with the door wide open. 😉 

 

Two other Oregon Tritons mating, opercula to the side. Like the mood lighting? You’re welcome.

 

Another Leafy Hornmouth with operculum visible at the bottom of the snail’s foot. And yes, there’s a Scalyhead Sculpin here too.

 

Another Red-Trumpet Calcareous Tubeworm. This one is out of its tube. There’s great diversity in colour in the species. See the trumpet-like operculum on the right?

 

Oh oh. This Red Calcareous Tubeworm has 7 kleptoparasites near!

Beware of taxi-crabs and “Cling like hell to your rock”

Oh how did I get to be today-years-old without knowing of this Robert Service poem that is so timely and speaks for a limpet?

His poem “Security” includes:

So if of the limpet breed ye be,
Beware life’s brutal shock;
Don’t take the chance of the changing sea,
But – cling like hell to your rock.

Yes!

Full poem is below which includes life lessons about taxi-crabs 🦀

Keyhole Limpet which I photographed near Port Hardy. Diodora aspera builds a shell up to 7.6 cm across.

 

Security
Robert Service

There once was a limpet puffed with pride
Who said to the ribald sea:
“It isn’t I who cling to the rock,
It’s the rock that clings to me;
It’s the silly old rock who hugs me tight,
Because he loves me so;
And though I struggle with all my might,
He will not let me go.”

Then said the sea, who hates the rock
That defies him night and day:
“You want to be free – well, leave it to me,
I’ll help you get away.
I know such a beautiful silver beach,
Where blissfully you may bide;
Shove off to-night when the moon is bright,
And I’ll swig you thee on my tide.”

“I’d like to go,” said the limpet low,
“But what’s a silver beach?”
“It’s sand,” said the sea, “bright baby rock,
And you shall be lord of each.”
“Righto!” said the limpet; “Life allures,
And a rover I would be.”
So greatly bold she slacked her hold
And launched on the laughing sea.

But when she got to the gelid deep
Where the waters swish and swing,
She began to know with a sense of woe
That a limpet’s lot is to cling.
but she couldn’t cling to a jelly fish,
Or clutch at a wastrel weed,
So she raised a cry as the waves went by,
but the waves refused to heed.

Then when she came to the glaucous deep
Where the congers coil and leer,
The flesh in her shell began to creep,
And she shrank in utter fear.
It was good to reach that silver beach,
That gleamed in the morning light,
Where a shining band of the silver sand
Looked up with with a welcome bright.

Looked up with a smile that was full of guile,
Called up through the crystal blue:
“Each one of us is a baby rock,
And we want to cling to you.”
Then the heart of the limpet leaped with joy,
For she hated the waters wide;
So down she sank to the sandy bank
That clung to her under-side.

That clung so close she couldn’t breath,
So fierce she fought to be free;
But the silver sand couldn’t understand,
While above her laughed the sea.
Then to each wave that wimpled past
She cried in her woe and pain:
“Oh take me back, let me rivet fast
To my steadfast rock again.”

She cried till she roused a taxi-crab
Who gladly gave her a ride;
But I grieve to say in his crabby way
He insisted she sit inside. . . .
So if of the limpet breed ye be,
Beware life’s brutal shock;
Don’t take the chance of the changing sea,
But – cling like hell to your rock.

 

I ensured this is indeed Robert Service in all his glory by ensuring it was in the “The Complete Works of Robert Service” (1945) but could not find further detail on when he wrote it.

My additional posts featuring limpets:

 

Who You Calling “Unstable”?

Don’t you hate when people use a provocative “hook” to get you to read their material? Yes, that’s what I’ve done but I promise you, it is worth it.

While I think all of us are a little unstable right now, this blog is not about me. It’s about the astounding adaptations of a little limpet assigned the name of “Unstable Limpet” (Lottia instabilis). 

Unstable? This species just limpetted along on its own evolutionary path!

Most other limpet species are shaped so they can suck down securely on a FLAT surface for protection This works well because these most often graze on algae encrusted rocks. But the Unstable Limpet can secure to a ROUNDED surface.

Which rounded surface? Oh I will never forget the first time I noticed this species and realized the marvel of the adaptation. Unstable Limpets are shaped to be able to hunker down on the cylindrical stipes (stem-like structures) and holdfasts of the kelp species upon which they also feed!

Screen grab from “Invertebrates of the Salish Sea”. Caption: “The uneven edges of the shell of Lottia instabilis can easily be seen in this end and side view. The shell is shaped to fit snugly around a round stipe instead of a flat surface.”

I suspect that, like their flat-shelled brethren, Unstable Limpets have a specific spot to which they “home” and where their shell fits perfectly.

As is supported by others’ observations, I have found Unstable Limpets living / feeding on Old Growth Kelp (Pterygophora californica) and Split Kelp (Laminaria species).

Underside of an Unstable Limpet on the stipe of kelp.
An individual with a lot of coralline algae growing on its shell.

I hope that this little limpet leads to you reflect anew on the wonder of the natural world around us and . . . about how being “unstable” just might mean being better adapted to the conditions you are in. It may even be of benefit in having a unique place and perspective in the world. 🙂

Below are further details about the species and an explosion of my photos documenting them.

Unstable Limpets and a Brooding Anemone on the stipe of Old Growth Kelp.

Size: To 3.5 cm across

Known range: Northern Alaska (Kodiak) to Southern California (San Diego) from the intertidal to 73 metres depth.

Variation: Greg Jensen reports that: “Some members of this species settle on rocks, where they develop a more conventional limpet sharp and are difficult to distinguish from other limpets. This rock form was previously known as Lottia ochracea.” (Source: Jensen)

Behaviour: If touched by predatory sea star species, the Unstable Limpet “vigorously” runs away. Predatory sea star species referenced in the study are Six-Rayed Stars( Leptasterias hexactis), Sunflower Stars (Pycnopodia helianthoides), and Ochre Stars (Pisaster ochraceus ). It was unclear to me from reading a summary of the research (and being unable to find the original paper) if this response behaviour is different if the Unstable Limpet is on its “feeding scar” (a bit of an indentation in the surface of the kelp). It may be that it responds then like the Seaweed Limpet (Discurria insessa) which “usually responds to contact by elevating its shell (“mushrooming”) and rocking from side-to-side, but rarely moving away from the scar.” (Source: Snail’s Odyssey).

Little limpet. Long stipe of kelp.
This individual may have had another limpet species feeding on the algae on its shell.
I believe you can see the scars here of where the limpet has been feeding on the kelp.

The following photos offer additional perspectives on two of the individuals shown in photos above.

I believe you can see where this individual has been feeding and yes, thats a lovely hat of algae that is growing on the shell.

Sources:

  • Jensen, Gregory C, Daniel W. Gotshall, and Miller R. E. Flores. Beneath Pacific Tides: Subtidal Invertebrates of the West Coast. , 2018. Print.
  • Lamb, Andrew, Sheila C. Byers, Bernard P. Hanby, Bernard P. Hanby, and Michael W. Hawkes. Marine Life of the Pacific Northwest: A Photographic Encyclopedia of Invertebrates, Seaweeds and Selected Fishes. Madeira Park, BC: Harbour Publ, 2009. Print.
  • Homna, L. 1995. DISTRIBUTION, ABUNDANCE, AND REPRODUCTION OF THE ALGAL SPECIFIC LIMPET, LOTTIA INSTABILIS, Master’s Thesis. Moss Landing Marine Laboratories, San Francisco State University. 77pp.
  • Snail’s Odyssey; Limpets & relatives – Predators & Defenses: Escape-crawling from Seastars
  • Walla Walla University. Invetebrates of the Salish Sea – Lottia instabillis

Abseiling Sea Snail

Go ahead, say that 5 times “abseiling sea snail, abseiling sea snail, abseiling sea snail . . .”

Now that you’ve warmed up and possibly developed a lisp, here are some details about a marine snail species that can climb, has an incredible sense of smell, and can deter much bigger predators.

Meet the Wrinkled Amphissia. No, I do not make up these names.

Amphissa columbiana can be up to 3 cm long, and is also known as the “Wrinkled Dove Snail”. 

 

Climbing

In this species, a gland near the foot secretes thick mucus that allows them to climb up and down and suspend themselves in the sea.

See the two photos below. I know it is so difficult to see the mucus strand.

Scavenging

Where are they abseiling to?

These marine snails are big time scavengers and are very active, using their long siphon to smell out the dead (photo below shows the siphon well).

It appears they can detect the chemicals of decay incredibly well in the water. Often a pile of them are scavenging together.

Wrinkled Amphissa amid Fringed Filament-Worms. If you look really closely you can even see some of the snail’s eggs attached the shell of the snail in the foreground. ©Jackie Hildering.

 

From Braidwaithe et al 2017 regarding feeding. “They appear to locate food resources primarily through chemosensory cues, often following conspecific mucus trails and sometimes congregating around actively feeding sea stars. The chemical cues that draw A. columbiana to food act as feeding stimulants; the addition of scent from a damaged animal induced the snails to feed on healthy prey. The ability to sense chemical cues from damaged animals, including those being consumed by feeding sea stars, creates scavenging opportunities other gastropods may be unable to exploit.”

 

Wrinkled Amphissa aggregation scavenging on a dead Rat Fish. The much larger snails feeding here are Oregon Tritons (Fusitron oregonensis to 13 cm long).The Tritons might follow the scent trails of the Amphissas to the food!

 

Photo above and below. Wrinkled Amphissas and Oregon Tritons snacking on a dead Lingcod. Nothing is wasted in the wild. ©Jackie Hildering.

Biting

They also have a wicked defense against sea stars where they insert their mouth parts (proboscis) into one of the grooves on the underside of the arms of predatory sea stars, biting a nerve.

From Braidwaithe et al  2010″The injury, which generally repelled the attacking sea star, immobilized the affected arm, rendering it useless for several days. The biting defense appears to be effective against several sea star species and may reduce predation on A. columbiana.” Some crab species do feed on them. 

Such remarkable adaptations in a sea of remarkable organisms which means I will be writing blogs and allotting abundant alliteration for a long, long time to come.

Adapting over thousands of years

I am sharing the photo below to give a sense of the diversity in the mollusc phylum to which snails belong.

“Mollis” means soft in Latin and the molluscs are our soft-bodied terrestrial and marine invertebrate neighbours. Their phylum is the second largest (the insects take first place). Note that all the organisms in this photo start off as larvae in the planktonic soup of the Ocean.

You can imagine how excited I was to chance upon  5 highly diverse marine mollusc species in one small area.

 

Details about the species in the photo:

– To the left of the Wrinkled Amphissa is a Keyhole Limpet who makes its own hat-like shell and grazes on rocks (preferred diet is bryozoans). Limpet species need to suction down hard on a flat surface because they do not have a shell to cover its underside. The individual here is in a risky position as a predator could easily flip and consume limpet. Too cool not to share with you is that engineers have found that the “teeth”  of limpets (the radula) are made of the strongest biological material ever tested (and the teeth are less than a millimetre long)! Note that marine snails like the Wrinkled Amphissa are protected not only by a shell, but they have an operculum which serves like a door to close the entrance to the shell when the snails withdrawn into its shell.

– Below the Wrinkled Amphissa, a Blue-Lined Chiton. Chitons make 8 plates to protect themselves. They are grazers like limpets. They too need to be able to suction down to protect themselves but do not need to be on a flat surface since the plates allow them to “contour” onto the surface.

– To the right of the Wrinkled Amphissa is a species of sea slug known as the Pomegranate Aeolid. It has “naked gills” and is therefore in the group of sea slugs known as “nudibranchs”. Sea slugs are marine mollusc without ANY shell or plates for protection. They are protected by feeding on animals with stinging cells (nematocysts) which become incorporated into those structures on its back (they are called cerata and also function as the naked gills for respiration). Specifically, Pomegranate Aeolids feed on Raspberry Hydroids which were only acknowledged as a new species in 2013. Scientific name is “Zyzzyzus rubusidaeus” and again, I do NOT make up these names. 🙂 See photo below.

– Below the chiton, if you look very carefully, is a very tiny sea slug species. I believe this is a Sea Cherub – a type of sea slug that swims and does not have naked gills (and therefore is not a nudibranch).

Not in the photo but to be considered too in the incredible diversity among marine molluscs is – octopuses!

Pomegranate Aeolid feeding on Raspberry Hydroids. ©Jackie Hildering.

Sources:

Anita Brinckmann-Voss & Dale R. Calder (2013). “Zyzzyzus rubusidaeus (Cnidaria, Hydrozoa, Tubulariidae), a new species of anthoathecate hydroid from the coast of British Columbia, Canada” (PDF). Zootaxa. 3666 (3): 389–397.

Lee F. Braithwaite, Anthony Rodríguez-Vargas, Miles Borgen, Brian L. Bingham  (2017).”Feeding Behavior of the Wrinkled Dove Snail Amphissa columbiana,” Northwest Science, 91(4), 356-366.

Lee F. Braithwaite, Bruce Stone, Brian L. Bingham (2010). “Defensive Behaviors of the Gastropod Amphissa columbiana,” Journal of Shellfish Research, 29(1), 217-222.

Who Goes There? Dizzying tracks in the sand.

Let me take you on a little mystery that filled me with big wonder, inspiration and happiness.

It goes back to July of 2017 when I was naturalist around Haida Gwaii with Maple Leaf Adventures.

Let’s make it a photo essay.

To set the stage, here’s the boat and the crew.

Crew from left to right: Mate -Lynsey Rebbetoy, Deckhand -Terese Ayre, Naturalist -You-Know-Who, Captain- Ashley Stokes, Chef -Yasmin Ashi.

You’ll note that the beautiful, historic sailing ship was operated by an all female crew on this trip. Important to note? Yes, but let me not digress.

Here’s the beach at Woodruff Bay near Cape St. James.

The discovery was made by the child I was so glad was on the trip.

Meet Kay from Germany.

Like any smart, curious and observant young person would, she asked what had made the crazy, convoluted patterns in the sand.

Here’s a closer look . . .

. . . and an even closer look.

I didn’t know what species had made those remarkable, dizzying tracks. But, the best things had come together – a mystery, a child, and the chance to discover the answer together.

We struck out to solve the mystery and found lots of little clam shells near the tracks.


We looked more closely at the tracks.

And found the tiny clams IN the tracks.

And then we noted what they were doing. They were licking the sand!

We had found the animal that was making the tracks and concluded the tiny clams must be feeding on organic material in this way. It is known as “deposit feeding” whereby the bivalves use their inhalant siphons to sweep the sand for detritus and microbes = snacks.

We were in awe at thinking of how much sand they must process to leave such long individual tracks and that they must be doing this quite quickly.

Upon returning to the ship, I was able to use the resources there to determine that the tiny clam was some species a “Tellin”.

However, it took my emailing my mollusc expert friends to have the species of Tellin confirmed.

Naturalist supreme, Bill Merilees, let me know I had “met British Columbia’s most beautiful clam Tellina nuculoides, the Salmon Tellin.” He also shared the results of his work to study their growth rings (imagine the dedication needed to count the growth rings of a large sample of tiny clams.) Bill’s research suggests Salmon Tellins can live to age 11 or 12.

Armed with their species name, I was able to find out a bit more.Their maximum size is 2 cm and their range is from southern Alaska to northern California. I presume the “salmon” in their common name refers to their beautiful colour.

I became even more awe-inspired to learn that research supports that bivalves like Tellins select particles based on physical and/or chemical properties that are poorly understood! (Source: https://doi.org/10.1016/j.jembe.2004.03.002.)

Imagine THAT while you watch my blurry video of the Salmon Tellins licking the sand.

To conclude, I will resist all the puns I could be using to be “tellin” it like it is. (Oops, clearly I am not entirely successful in resisting.)

Rather, I will share the quote with which mollusc expert Rick Harbo responded when I asked him about the species and their tracks.

He reflected on the tracks made by mollusc species who feed in this way with the words of Gandalf from Lord of the Rings  . . .

“All who wander are not lost”.

 

The happiness that comes with connection to nature and making discoveries – Kay with a boa of “Feather Boa Kelp” that had washed onto the beach. Be on the lookout for Salmon Tellins on a fine sand beach from Alaska to California. Note that other mollusc species (and worms, some sea slugs, etc) also leave tracks in the sand. More on other trail-blazing species in the future.