Reading the shells?

  

While in Monterey last weekend, we were thinking about southern species that might become more common farther north if a major El Niño event arrives this fall/winter.  For fun, while walking the beach we gathered some shells and ended up with 11 of these species.  We used all of them to spell out El Niño in the photo above.

Three barnacles: Megabalanus tintinnabulum, Paraconcavus pacificus, Tetraclita rubescens

Six snails: Acanthinucella punctulata, Californiconus californicus, Hespererato vitellina, Atrimitra (formerly Mitra) idae, Pseudomelatoma torosa, Pseudopusula (formerly Trivia) californiana

Two limpets: Fissurella volcano, Lottia gigantea

You can click on the image above for a larger version, and here's an example with labels, a close-up of the "E":

 

 

 

P.S.  If you're interested, you can follow NOAA's El Niño predictions at this link (updated monthly). 

The color purple

  

Eric spotted this beautiful Striped Dogwhelk (Nucella ostrina) yesterday (2 May 2025).  This is a common snail in the rocky intertidal zone in northern California, but we can't recall seeing purple variants of Nucella ostrina, so here's a photo for the record.

More often, Striped Dogwhelks are versions of black, brown, gray, or white.  Here are some individuals feeding on barnacles:

 

 

 

Occasionally you'll spot an orange Nucella ostrina —they really stand out! 

 

 

Breeding experiments suggest that color variation in Nucella ostrina likely has a genetic basis (Palmer 1984).

Dusky?

  

Dusky Tegula (Tegula pulligo), a beautiful snail in the low intertidal zone, photographed on 29 January 2025.

P.S.  In this case, I'm not sure about the name "dusky" -- how about pearlescent lavender?  :)

The door to the moon?

  

The operculum, sometimes called a "trap door", to a Lewis's Moon Snail (Neverita lewisii).  This is the part attached to the snail's foot that seals the opening to the shell when the animal pulls in.  This operculum was 2¾ inches (7 cm) long.

Interestingly, the inside of the operculum was very reflective and looked quite silvery in the overcast light of the fog today (17 August 2024).

Looking out

  

 The eye of an abalone (the dark spot at the base of the tentacle).  

What do they see? 

ADDENDUM (9 July 2024): P.S.  I've received some questions about where the eye is exactly, so here's the same photo with the eye circled:

Who's the culprit?

  

This is a scene we came across after finishing field work this morning (9 May 2024).  Some empty-looking whelks (Nucella ostrina) on the sand...and upon closer inspection, their opercula nearby (the operculum is the "trap-door" on the bottom of a snail's foot that seals the opening to its shell when the snail is pulled in).

It looked like the snails had been eaten by a predator, but we couldn't recall seeing this before, so we looked around a little more.

We found even more evidence that something had been eating both whelks and limpets.  Here are a few examples, including snail shells and overturned limpet shells with most of the soft parts missing, but with a thin ring of tissue, evidence that they had been eaten recently:

 

 

So...who was responsible for eating these snails and limpets?

 

We weren't sure, but we kept looking, and Eric eventually spotted a clue.  Tracks in the sand around some of the predated shells:

 

 

 

After thinking through the possibilities, we're guessing these footprints might belong to a rat (!).

 

Rat predation on intertidal invertebrates has been documented previously (Thanks to Sergio!), but we don't recall seeing it locally before.  Maybe because there was a lot of sand at this site it was easier to notice the empty shells and the tracks in the sand.

 

Here's a close-up of one track in case anyone can help us with an identification.  The track was ~1 cm across.

 

 

 

You learn something new every day!

ha`uku`uku`ula`ula and unauna

Two fun invertebrates found snorkeling in Poipu today (3 April 2024).  

Above, meet ha`uku`uku`ula`ula, or Red Slate Pencil Urchin (Heterocentrotus mamillatus).

Below, check out this tiger-striped crab — a Cone Shell Hermit Crab (Ciliopagurus strigatus).  (The general Hawaiian name for hermit crab is unauna.)

Fun fact — Eric learned that this crab’s flattened body and legs allow it to live within the shells of cone snails (Conus spp.), which are rarely used by other hermit crab species.

We have been feeling very lucky to spend a little time learning about these amazing animals.

Mahalo to Eric for the great photos!

Up close and purple

  

I've been surveying for Purple Sea Snails (Janthina umbilicata) and encountered some washed up this morning (5 March 2024).  Janthina is rare in our area, and these snails were still alive, so I took a few photos for the record.

Remember that these snails float upside down at the surface of the ocean, hanging from their own bubble raft!  So these photos show the snails suspended below the surface of the water.

Above, note the bifurcate or forked tentacles, with one long and one shorter branch (highlighted with black pigment).

Next -- look for the large, rounded, black foot.  Janthina reaches up to collect a pocket of air and then surrounds it with mucous to create a bubble to add to its raft:

 

 

They also use their foot to smooth the bubble raft:

 

 

Janthina is a predator, feeding on By-the-wind Sailors (Velella velella) and Portuguese Man O' War (Physalia physalis) when available.  They have a tubular proboscis to reach out and grab prey, and a rasp-like tongue (radula) at the end of the proboscis: 

 

 

 

 

 

P.S.  If you happen to see Purple Sea Snails washed up on the beach this spring, I'd love to hear about your observations!

A short walk

  

Pretty cute, huh?  Eric filmed these two juvenile marine snails tonight.  They're only ~1 mm long.  He put together a nice video clip of them, too — see below.  [If you're reading this in an e-mail, click on the title of the post to see the video on the NHBH website.]

These snails are a little unusual in that they look quite different in this stage vs. how they look as adults.  

We thought we'd post the footage first to let you explore and wonder about which species this might be.  Any guesses?  I'll share more info about them tomorrow!

Blue moon

  

Close-up of a Shark Eye Moon Snail (Neverita duplicata) at Duxbury Beach, Massachusetts, 12 December 2023.  This one was ~1 cm across.

Snorkel in the sand

 Okay, here's the mystery photo from last night:

 

 

This is a tricky one, and I'll admit I wouldn't have known what it was myself (until now!).

 

The next photo will show more of the animal.  I'm guessing you'll be familiar with it, although you might not have observed this species in action under water:

 

 

 

This is a Purple Olive Snail (Callianax biplicata, formerly Olivella biplicata).  Purple Olive Snails live on sandy beaches and the snails are often buried below the sand, so they might not be visible (except for their winding trails).  Their shells are sometimes washed ashore.

 

While burrowing, this snail had its siphon extended above the surface of the sand like a snorkel.  The siphon provides access to water which will be drawn into the mantle cavity of the snail, passing over the gill.  The water will also flow by sensory receptors that can detect waterborne cues — picking up information about things like food, other snails, possible predators, etc.

 

Here's one more photo showing a bit more of the shell:

 

 

The next time you see an olive snail, if it's under water, you can look closely for the small tubular siphon in front of the snail!

P.S.  Thanks to Eric for the great photos!

Meet Marsenina!

 

 

A fun view of an often overlooked snail — meet Marsenina rhombica!

With a large mantle that almost completely envelops the shell, this snail can be mistaken for a nudibranch.  But note the tentacles, the lack of rhinophores, the inhalant siphon (a short tube visible between the tentacles), and that you can see some of the shell at the top of the mantle (the part that looks white and shiny).

 

Marsenina has adaptive coloration — they are often associated with compound ascidians (colonial sea squirts), but when they're on the sea squirts, they almost disappear!

 

If you're curious about the shell, here's a scan of one I found years ago (see below).  The shell is very thin and shaped like a small abalone with a flattened spire and a very large body whorl:

 

 

P.S.  Many thanks to Caroline for spotting this snail and for Eric for scanning the shell!

Isopod and friends

  

We've been busy doing surveys in the field during the low tides recently, but here's an isopod photo from back in February -- a Blunt-tailed Isopod (Idotea urotoma) photographed in the low intertidal zone.  

Among other things in the photo, you can see pale pink crustose coralline algae, a small iridescent snail, Lirularia sp., and a darker pink and red bryozoan (Integripelta bilabiata, formerly Eurystomella).

Little pearl

 

 

Pear Marginella (Granulina margaritula), a very small marine snail —  the shell is only ~2-3 mm long.  Photographed in the low intertidal zone on 18 February 2023.

 

I posted a short video clip of this species several years ago, so if you'd like to see this snail in action, see "Shield up" from 6 December 2015.

 

Eating peanuts

  

Here's a fun story.  In Monterey County, I came across an Ida's Mitra snail (Atrimitra idae, formerly Mitra idae).  Although we see their shells occasionally in Bodega Bay, I haven't seen a live snail in the field, so I was excited to find one.

I have read that Ida's Mitra specializes on eating an unusual prey item —  peanut worms (sipunculans).  I've always been curious about how that works, since peanut worms often live deep within rock crevices.  

After photographing this individual, I looked up to see a second Ida's Mitra not too far away.  I took a quick photo and noticed something brown that I wasn't sure about.  I was under the impression that Ida's Mitra's body was primarily white, so I wasn't sure what the brown part might be.  Here's the next photo and then a second even closer image from a slightly different angle:

 

 

 

 

Ahh!  This snail was eating a peanut worm!  That brown object is the posterior end of Phascolosoma agassizii, a common peanut worm in rocky shore areas.

I waited a while to see what would happen and took a couple more photos for the record:

 

 

 

 

I didn't see the position of the peanut worm change very much.  Later I read about two possible feeding strategies in this family of snails — (1) the snail could rasp a hole in the peanut worm's skin and then extend its proboscis into the peanut worm to access the inner tissues, or (2) the snail could swallow the peanut worm whole and digest it once it reached the stomach.  I can't say for sure which was happening here, but my instinct was that the snail was swallowing this peanut worm.

Later I found a different individual under water with its siphon fully extended, apparently searching for prey (it's likely they can detect the scent of a peanut worm in the water).  The siphon is the tubular structure above the head:

 

 

And I also encountered a very pretty juvenile snail:

 

 

 

Although I'm a big fan of peanut worms (see below), it was amazing to see this feeding behavior in the field.

 

 

 

Like granite

  

Fingered Limpets (Lottia digitalis), Eroded Periwinkles (Littorina keenae), and a few acorn barnacles (Chthamalus dalli) on Bodega Head granite, photographed 9 July 2022.

An iridescent neighbor

  

This snail can be quite common in the rocky intertidal zone, but it's small enough (only ~4 mm long) that you might not notice it.  Meet Lirularia succincta!  Photographed 4 July 2022.

The Dove Snail Attacks!

I had a bit of an eyebrow-raising experience today.  I was trying to photograph a common snail, the Carinate Dove Snail (Alia carinata).  This marine snail can be found in a variety of habitats, e.g., rocky shores in tidepools and among surfgrass and seaweeds and in harbors among eelgrass.  It's fairly small (most individuals are probably ~10 mm long), elongate, and usually brownish/black in color.  Here's an example:

 

 

This species is common enough that you can overlook it.  But I needed a photograph, so I was looking at several of them under a microscope today when I came across one in a puzzling position.  I wasn't sure what was going on at first:

 

 

 

So that's the snail, with its siphon extended up and to the right and its foot flat against the surfgrass blade (in this photo the foot has blue highlights).  You can see the snail's short tentacles, and you can also see a small dark eye on the right hand tentacle.  But what's below the tentacles?  Here's a side view:

 

 

 

Ahhh!  The snail had extended its proboscis (a tubular feeding structure) into an egg capsule filled with developing larvae.  It was vacuuming up the veliger larvae!  I hadn't seen this behavior before, so I wasn't sure I was interpreting it correctly at first, but there was no doubt.  The snail reached around inside the egg capsule and cleaned out almost every developing larva.  (The egg capsule/larvae belong to a different snail species, Lacuna marmorata.)

 

Even better, Eric wasn't far away and he came over just in time to capture a video of this fascinating feeding behavior (see below).  

 

I loved learning something new and unusual about a common local snail.  In some ways the name "dove snail" suggests a rather sedate snail, but I'll never look at Alia the same way again!

 

And here's the best part — the video!  Watch for the snail approaching the egg capsule, inserting its proboscis inside, then using suction and its tongue-like radula to ingest the tiny larval snails.  You'll see the radula flicking in/out at the tip of the proboscis.  (At this stage, the larval snails have shiny little shells.)

 

 

 

Many thanks to Eric for a memorable video!

 

Snail for breakfast

  

Last month when we were doing field work near Carmel, out of the corner of my eye I noticed this scene where a Striped Dogwhelk (Nucella ostrina) appeared to be eating a Black Turban Snail (Tegula funebralis).

Dogwhelks are predators that drill holes in the shells of their prey to access the soft inner tissues.  It's common to see Striped Dogwhelks eating barnacles and mussels, but we don't often see them eating other snails.  

To be sure, we pried the dogwhelk away from the turban snail and found the evidence (below).  The blue arrow is pointing to a drill hole along the edge of the snail:

 

 

 

And here's an even closer view so that it's easier to see the drill hole itself:

 

 

 

Evidence!

 

Little wonder

 

 

We've been working hard these past few days, but here's a quick shot of one of my favorite marine snails.  This is a pheasant snail, Eulithidium pulloides.  They're tiny!  Compare the shell to the sand grains in the photo.  I've posted about this species before, and I'm fascinated with the variable color patterns of their shells.  If you'd like to see some other designs, check out the post called "Six of a kind" from 21 August 2014.