Reconsidering

A couple of years ago, faced with snail egg capsules and an infant snail found with them, I tentatively identified them (with help from commenters here) as one of the rock snails, aka murex snails or Muricidae. I thought they were probably Trophonopsis orpheus, or another of the trophons. These prey on barnacles or mussels and other bivalves, and seemed to match some barnacle-eaters I'd had previously in the aquarium.

The hatchling, only a few millimetres long.

There were problems with the id; some references called it a subtidal snail, living at depths up to 180 feet. But I had found these in the upper intertidal zone. In Marine Life of the Pacific Northwest, it was the only rock snail that matched the snails I found, but again, it was supposed to be subtidal.

So every time I find another of these, or mention them, I spend some time reviewing the websites and books, looking for a closer match, a snail that fits everything I'm seeing in my tank.

And now, having the egg cases at hand, and confirming that these snails do, in fact, lay these eggs, I think I've been mistaken; that they are no trophons, after all.

Look at these egg cases. (Copyrighted, so you'll have to go there to see them. Here's the page; scroll to the second species.)

Now look at these, from my tank.

Tillie's eggs. A good match.

These are from the Leafy Hornmouth, Ceratostoma foliatum. This is another Muricid (rock or murex snail) that lives in the intertidal zone, but almost all the photos I find are of the full-grown adults; in these, the ribs are prominent, "leafy". The younger ones are like those in my tank.

This is fairly common to find intertidally.  The juveniles exhibit crosshatch sculpturing.  The axial ribs grow to large flares as it matures.  The adults may be plain white to purplish and may be striped.  At the base of the aperture there is a projecting tooth.  It lays a distinctive egg case. (From PNWSC.)

The Wallawalla.edu page adds more details: the siphonal tube of the Leafy Hornmouth is closed along its length, opening again at the tip. And the foot is a mottled cream colour.

(The siphonal canal of Trophonopsis is open.)

This is the youngest one in my tank, still quite small. The siphonal canal is completely fused along its length. The tooth is only visible from this angle as a slightly whiter spot. The shell is white with purplish stripes.

Here's the tooth, looking from the side.

Tillie, laying her eggs. The siphonal canal is closed, the tooth is near the entrance to the canal, and the flesh is a mottled creamy colour.

Down at the beach this afternoon, just below the high tide line, I was turning over rocks, looking at flatworms and a variety of eggs and egg cases. On one stone, I found several clumps of freshly-laid egg cases to match the ones at home. And there were the snails; some laying eggs, some eating barnacles. I turned each one over. Every one had the closed siphonal canal and the tooth.

Snail on rock, stony section of upper intertidal zone, Boundary Bay.

One snail in my tank looks like these, (but cleaner) but is much smaller. And its siphonal canal is open. It has no tooth. It's the oddball. Or it's too young to have developed yet. We'll see.

But. There's always a but.

On the Wallawalla.edu page, I see this:

Depth Range:  Low intertidal zone and subtidal to 60 m.
Habitat:  Found on rocky faces near barnacles and bivalves.  Avoids sand and mud. Most common in areas of strong surf ...

So I'm still not totally convinced; maybe other snails have the same egg cases, the same tooth, and the closed canal. I want to see if Mike and Tillie and their companion develop those big leafy wings as they grow larger. I'll keep on studying the reference sites and books until then.

What do you think?

Snail on snail

More aquarium snails; the oddballs

Unidentified snail on young trophon snail, probably Boreotrophon orpheus*.

*More on this species, and why I call it the oddball, tomorrow.

Awwwww!

Some intertidal snails are like rabbits. A Nassa snail in my aquarium, for example, chases down a mate, they indulge in a minute of frantic twisting and writhing, and then it's over. They go their separate ways without a backward glance.

Some, like the Eastern mud snails, Ilyanassa obsoleta, take their time, and prefer company. Lots of it. (See "... snail orgies".)

I've never managed to see the other invasive mud snail, Batillaria attramentaria, with a mate. However private they may be about it, they are definitely successful breeders, judging by the billions covering our beaches, and the 70+ in my tank. (How they all got here, I don't know; I didn't import that many on purpose!).

But the trophons! I never thought I'd be saying this about a basically faceless snail, but these critters are seriously cute.

Mike and Tillie, the trophon snails; pair of hermits using Mike as a seat; and a lonely limpet.

A couple of weeks ago, I reported on the trophon that laid her eggs in the tank. I thought at the time, that the second one was getting ready to lay her own, and that these would be infertile eggs. But there were no eggs forthcoming. Now I'm convinced that Snail #2 is male; we may end up with babies.

(I've got to quit calling them #1 and #2: from now on, it's Tillie and Mike. That's Tillie on the right, above, Mike on the left.)

After Tillie laid her first batch of eggs, she holed up for a couple of days, barely moving. Mike retired to the far end of the tank to stuff himself with barnacles. When Tillie was ready, she joined him. Then they explored the tank together, allways side by side. Wherever one went, the other followed, until Tillie laid her second batch of eggs. Then she rested for a couple of days and joined Mike again. She's just coming, now, out of her third round of rest after egg-laying, and she's on her way over to where Mike waits for her.

"We travel along, singing our song*,
Side by side."

*Or however it is that snails communicate. Spreading pheromones, perhaps?

Jugs full of eggs

Two years ago, in April* of 2012, I brought home a clamshell that contained, under a crowded community of snails, hermits, worms, and more, a set of little brownish jug-like things. Eventually, commenters identified them, tentatively, as Murex snail egg cases, possibly trophon snails.

"Jugs" Photo from 2012.

And now, the mystery is solved! Yes, they are trophon eggs.

Remember the two-toned trophon snail that has been eating barnacles in my tank? I brought her** home a companion from our last trip to the beach; another trophon, slightly smaller.

For several days, they've been circling each other, warily, approaching then backing off. Neither showed an inclination to bury themselves in the sand, or eat another barnacle. Today, only the newcomer was visible, though, until Laurie found the other hidden behind an abalone shell in the back of the tank in the evening. She was busy; laying eggs, in a sort of grid pattern stuck to the glass.

After an hour or so, the newcomer joined her. She stuck herself to Snail #1's shell and waited until she had finished.

I rigged up some lighting, and a mirror behind the tank, and took their photo in the mirror, since I couldn't even get the camera into the small space.

More "jugs", with their bottoms glued to the glass, facing us.

Snail #1 is finished, now. She's moved to the bottom. She looks skinny, as if the shell were now too big for her. Snail #2 is twisting herself around beside the egg cases; getting ready to lay her own, maybe?

*It looks like April is the egg-laying month for these snails.

** I wrote then, "*Most snails are hermaphrodites, but these ones have separate sexes. I don't like calling a conscious critter an "it", so I've opted for calling this guy a male." I guessed wrong. She's definitely female!***

***She needs a name. I can't keep saying Snail #1, #2.

Snail, out hunting

A week or so ago, I wrote about a two-tone trophon snail from Boundary Bay. At the time, I had been trying to get a photo of the siphon he extends through the canal at the tip of his shell, but he wasn't co-operating.

He finally showed up near the wall a couple of days ago, and let me get a few photos.

Trophonopsis orpheus, on an abalone shell against the wall. The tip of the siphon is just visible at lower right.

Climbing over a blade of eelgrass. The eyes are near the tips of his tentacles. The siphon is visible, extended through the siphonal canal.

How much he sees with those little eyes is debatable, but his main guidance system is the siphon. He's "breathing" in the water through the tube, and also "smelling" his way. A few hours later, he had found the barnacles on a stick on the far side of the tank, and was busy emptying the biggest.

And now he's back buried in the sand, digesting.

Bi-coloured snail

Sometime last summer, a snail I hadn't seen before came home from Boundary Bay with me, hiding in a bag of greens for my hermits. He* was small and dark, slate grey and brown, sort of whelk-shaped, nondescript. Nothing to write home about.

I added him to the tank with some trepidation; the whelks and their ilk are usually predators, and sometimes very hungry. I kept an eye on him, and on the possible food sources in the tank; there are a couple of clams, some mussels, always a few barnacles. When I do a thorough cleaning, I comb through the sand. The clams are still there. The mussels are bigger than they were. But the barnacles I've added just a bit ago are now empty shells.

The snail eats barnacles. Nothing else, it seems.

Barnacles are easy to come by, in quantity. He can stay.

Last August, heading up out of the sand.

He spends much of his time like this, half-buried in the sand, barely moving. Then for a day or three, he surfaces and goes looking for another barnacle, glues himself to the unfortunate choice, and leaves it gaping open and empty. Back to the sand to sleep it off.

About a month ago, on one of his food runs, I noticed how much he had grown. But the new shell seemed almost to belong to another snail entirely. It was almost white, in sharp contrast to the old slate-grey shell.

The white is dirty, now, algae-encrusted. But the divide is still there.

And the new shell is more ridged than the old section, possibly because the snail isn't being rolled around by fast currents.

He's a Corded trophon, Trophonopsis orpheus, aka Boreotrophon orpheus, a subtidal resident, rarely seen above the low tide line. I have only seen one before, an infant, newly hatched from the egg case.

Baby trophon, April, 2012. A few millimetres long. New, sharp sculpturing.

It looks like the dark grey colouring came from the shore where the snail was living, or from his diet. (Black barnacles?)

These snails are distinctive for their long siphonal canal, the tube that protects the siphon through which the snail "breathes" and finds prey. A good idea; the siphon is the most vulnerable part of this type of snail, sticking out well in front, soft and inviting.

Little Nassa, leading the way with her small, unprotected siphon. 

Trophon bottom, showing the siphonal canal. The opening and exit are just visible.

Flipping back the operculum (that reddish lid) to extend the foot.

Spotted orange and white skin of the foot. The siphon canal extends to the right, the direction of travel.

Muricid (whelks and their ilk - rock snails) shells are variably shaped, generally with a raised spire and strong sculpture with spiral ridges and often axial varices  . . .
Many muricids have episodic growth, which means their shells grow in spurts, remaining the same size for a while (during which time the varix develops) before rapidly growing to the next size stage. The result is the series of above mentioned varices on each whorl. (From Wikipedia)

The ridges, in the photo above, go top to bottom; the varices (sing. varix) go left to right. The shell building continues; it has turned the corner and started on the next lap, which will be bigger than the one just added. The raised lip where the shell turns is a varix.

The snail had been sitting on the pump for a couple of days, so I brought him out for a photoshoot. He didn't seem to mind sitting on plastic foam, and started to roam. I waited, hoping for him to extend the siphon, but there was no sign of it, probably because he was out of water. He's back in the tank now, and has buried himself again, without eating the last two barnacles I've brought him. Sulking, probably.

*Most snails are hermaphrodites, but these ones have separate sexes. I don't like calling a conscious critter an "it", so I've opted for calling this guy a male.