Three snails

 While I was looking for snail fur, I stopped to take other photos:

A pair of channelled dogwhelks.

They're usually busy eating barnacles, but for one day, they hung out together on the glass. All day. One is still there; the other is back at the barnacles. Spring is coming; I'm going to be looking for eggs soon.

Japanese rocksnail, Ceratostoma inornatum. I think.

I find shells of these on all our beaches these days, easily identified by their thick lips and narrow opening. For a while, I brought some home for my hermits. They absolutely refused to use them. Any other snail shell from the beach is fine. Unfortunately, most of the ones I find on the upper beach are these.

I wondered about this; why are the hermits so dead set against just this species? Could it be because this snail is an import, an invader, not one the hermit clans grew up with?

It's a carnivore, like the dogwhelks, but it prefers oysters. Young oysters; it occasionally tries to drill through the heavy, mature oyster's shell in the tank, but gives up after a while and eats another mussel instead.

~~~~~~~~~~~~~~~~~~~~~

Mientras buscaba pelo de caracol, me detuve para sacar fotos de otros residentes del acuario.

Primera foto: dos caracoles marinos, "dogwhelk", depredadores que comen bálanos. Estos dos casi siempre están ocupados en los bálanos, pero por un dia, todo el dia, se quedaron quietecitos juntos. Hoy, uno ya está de vuelta con los bálanos; el otro duerme en el vidrio. Viene la primavera; voy a estar buscando huevos de caracol un dia de estos.

Segunda foto; otro caracol depredador; este come ostiones. Encuentro sus conchas en todas las playas en estos dias; se identifican facilmente por los "labios" gruesos y la apertura angosta. Por algún tiempo, las traía a casa para mis ermitaños, pero se rehusaron totalmente a usarlas. Cualquier otra concha que les traigo está muy bien. Mala suerte, para ellos, es que la mayoría de las conchas que hallo en la parte superior de la playa son de esta especie.

Me preguntaba porque sería que justamente esta especie no les gustaba. ¿Sería tal vez porque este caracol es importado, un invasor, y no uno con que los ermitaños locales se desarrollaron?

Es carnívoro, como los primeros, pero prefiere los ostiones. Ostiones jóvenes; de vez en cuando trata de taladrar la concha del ostión grande en el acuario, pero después de un tiempo de trabajo futil, se aburre, y va a comer un mejillón.

Limpet, snails, etc.

A few August aquarium critter shots: the residents who wander close to the glass, where bubbles and amphipods and bits of seaweed don't get in the way.

LImpet. The yellowish bits are limpet poop.

Limpets are built like snails; because they have retreated into a shell that opens only on one side or one end (snails), their anatomy has to be twisted away from the "normal" head to tail shape of other animals. For example, they have two kidneys, as do we. But the left one is tiny, because it just wouldn't fit otherwise. On the exposed bottom of a limpet, we see the mouth, two tentacles, with their eyes, the big foot, with the gills laid alongside. (Not visible in this photo.) And the anus is up near the head. Which could be a problem.

The anus of most molluscs and indeed many animals is located far from the head. In limpets and most gastropods, however, the evolutionary torsion which took place and allowed the gastropods to have a shell into which they could completely withdraw has caused the anus to be located near the head. Used food would quickly foul the nuchal cavity unless it was firmly compacted prior to being excreted. (Wikipedia) (My emphasis. "Nuchal" means near the neck.)

One of the tinier hermit crabs. The eelgrass is about 1/4 inch wide; half its width is visible here. So the hermit, shell and all, is about 3/8 of an inch long.

Channelled dogwinkle, Nucella canaliculata. It eats barnacles, prefers mussels. I don't bring many mussels home for them, though; they (the mussels) trap and kill my hermits.

Channelled dogwinkle finishing off a stonefull of barnacles. There is one still alive, still cheerfully trolling for supper, at the bottom right. Sometimes I feel sorry for them.

Bejewelled (or at least, be-sanded) Japanese nassa, Nasarius fraterculus. The fine sand must be stuck to the algae growing on the shell. Average sand grains beneath it: these are not stones.

Knobbly column of a pink-tipped green anemone. The neighbours are a limpet, a couple of Asian mud snails (invasive Batillaria), a hermit, and another pink and green anemone. There are 11 of these in the tank now; they keep cloning themselves.

And the chiton is still on his moon snail shell.

No two alike

Whelks.

Wrinkled dogwinkle, Nucella lamellosa. (Probably) Stories Beach.

These snails are extremely varied, both in colour and shape.

A most peculiar species because of its ability to vary so much in shape, color, and texture from one individuals to the next. ... It is one of the most common intertidal whelks in the Pacific Northwest. (From Wallawalla.edu)

A fan of this species, Dan Yoshimoto, has a page of shells found on both coasts of Vancouver Island, and on the mainland, from California to Oregon: over 200 shells, not counting the group photos at the bottom of the page, and so variable that it is difficult to believe they are all the same species. Go see.

Peachy

Whelk and periwinkles.

In a shallow tidepool, upper intertidal zone.

On sun-warmed rock

Snoozing Snails:

Actually, under sun-warmed rock. The snails were clustered in the chilly, wet dark underneath. I flipped the rock back after I'd taken a photo.

Every stone I turned over on this very stony beach had its own little community of snails sleeping away the lazy spell between tides, in the dark and cold.

Bedroom community, at Oyster Bay

Empty nest

Fresh, green veggies are good. And if they're eelgrass, they're being used as salad, as gym equipment, as shelter for a variety of critters.

But old, brown, even rotting veggies are even better, if you live in the intertidal zone. A blade of decayed eelgrass is a gourmet dish, if you're a hermit crab. Or an amphipod.

And they make a good nursery for babies just starting out into the wide world; the food underfoot is puréed already, the tough fibers and skins gone. Easy munching!

That's what I think happened here:

Five abandoned egg cases. There may be a baby or two still deciding to leave.

I don't know what animal laid these; I don't recognize the form of the cases. It's probably a snail, but not one I can identify.

The fuzzy stuff is a mass of diatoms, or possibly bacteria. A hermit crab will be along soon enough to clean all that out, leaving only the empty egg cases.

...

And there's more! I'm puzzling over a batch of green teeth. I'll post them tomorrow.

Slimy!

I always know where my bubble shell snails are; all I have to do is look for the trail of slime bubbles and follow it.

Bubble shell, Haminoea japonica, and Nassa snail, at water surface.

Bubble shells wear their shells inside the body; not much use for protection. Instead, they produce a prodigious amount of mucus and often shelter inside a circle of the stuff. When they leave, it remains stuck to the surface, sometimes on the glass of the aquarium, sometimes rolled into a blob of sand.

The rest of the slug and snail tribes, from our garden slugs to nudibranchs and limpets, are slimy beasts, too, if not as productive.

In snails and sea slugs (nudibranchs), each species has a unique chemical composition to their slime, and within each species, individuals can even be identified. (Ucluelet Aquarium)

This slime is useful stuff. On land, or underwater on scratchy rocks and sand, it serves as a lubricant for the tender foot as it slides along. For going up vertical walls, and sleeping on the underside of a rock, it's a glue.

But that's not all it's good for.

• It's a road map. A snail can follow her own trail home at the end of the day's hunt. Or another may follow her trail, hoping to mate when he catches up with her. I see the Nassa snails doing this often, on the wall of the tank.

• Or a carnivorous snail (or a worm) can follow the slime trail of his prey.

• The slime coating keeps an intertidal critter moist at low tide, when he is exposed to the air.

• It serves as a defense. Some nudibranchs, some sea stars, and other critters exude a thick layer of slime, really sticky slime, when they are disturbed or threatened.

• It may protect the skin against bacteria and parasites.

• And don't forget reproduction! Remember the leopard slugs, that hang from branches on two threads of their own slime to mate in the air? (Video) Other snails transport sperm in a mucus environment, if not as dramatically. And then the moon snail uses her slime to glue sand grains together to build her big "sand collar" egg case.

Bubble shell slime trail on aquarium wall

And I've discovered another function of the slimy goop. When a bubble shell is knocked off his blade of eelgrass, or off his spot on my tank wall, he rappels down to the sand on his slime rope, landing gently at the bottom. Helpful, when your shell is so fragile.

And a couple of days ago, a hermit crab knocked a zebra leafslug off the top leaf of the seaweed. As I watched, the slug floated across to the far side of the tank on a thread of slime, rather like a ballooning spider on her silk.

Handy stuff, that slime!

Rainy afternoon on the beach

My little aquarium was getting bare, and the hermit crabs looked bored; nothing to eat but crab munchies, nothing to climb on but bare shells. It has been raining off and on, but Sunday afternoon it looked as if the sun might even deign to show its face. I took the chance and went down to the beach for goodies to re-stock the tank with.

The rain started as soon as I stepped onto the shore. But it was just a gentle drizzle, straight down; there was no wind. And the tide was high, the eelgrass at the edge still green and fresh. I walked south, filling my bag. Eelgrass bearing limpets, hydroids and tunicates; sea lettuce for the crab; stones covered with barnacles to feed the leafy hornmouth snails; green, knobby rockweed plants, mainly for climbing on. A small male crab to keep my female company. A couple of unusual Hairy hermits, very large, very hairy, and wearing the tiniest of breechclout shells. And a few periwinkle snails; Val, the big anemone, loves these.

And then I walked back northwards, taking photos. Grey water, grey stones, grey sky. It was beautiful, but no camera could ever capture it; the beauty compounded of the smell of rain on salt water, the whisper of waves, the feel of slow raindrops on my face and hands, the muted call of birds in the distance, the grey light and the glint of water on stones and seaweed.

I took a few photos, anyhow.

A few walkers, well bundled up for the rain.

Sailboats at anchor. Barely visible in the distance, a line of geese with a few ducks.

A rotting log, colonized by barnacles, snails and hermits.

Three kinds of snails. And can you find the orange-striped green anemone?

Stones, barnacles, seaweeds at the top of the tide.

Grey on grey, with every other colour muted.

At the top of the beach, semi-protected by the cement walls, a sea rocket in full bloom. They seem to shed the water, even in a hard rainstorm.

At home, I discovered that I'd brought back more than I'd thought, hitchhikers on the eelgrass; a blue anemone and more hermits and snails (some quite tiny). More on these, later.

A never-ending supply

Val, the big burrowing anemone eats snails. Eats them and spits out the shells for the hermit crabs to wear. Or glues them to her column.

But it's not just any snail that she likes; she prefers the upper intertidal periwinkles that climb to the top of the tank and occasionally drop straight into her mouth. One gulp, and they're gone.

She'll reject the Asian mud snails, as if the longer, sharper shell gets stuck in her throat. Or maybe she just doesn't like the taste.

And I've never seen her eat a little Nassa, but somehow there's always a supply of new empty shells; she must nibble on them at night, when I'm not watching.  And somehow, although I don't bring Nassas home with me, when I clean out the tank, I find dozens of these snails plowing through the sand. They're breeding here.

The Japanese Nassa, Nassarius fraterculus.

I've watched them mating often; one snail chases down another. When he catches up, there's a quick writhing and twisting interaction, and then they both hurry away. I've never seen their eggs; they lay them in the sand, in small capsules containing two or three eggs each, and the juveniles are as small as the sand grains. (Here's a video of mating Nassas, the eggs, and emerging juveniles.)

The recent pump disaster didn't seem to worry them at all; they're as active and numerous as ever.

This may be Nassarius fostatus. Or maybe not.

Babies, babies!

The snails are hatching! Three are out and exploring their new home, already!

I'll have photos asap.

Couldn't wait to crow!

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.

Maternity ward, underwater

Mike and Tillie, the large snails in my aquarium, have been together for 6 months now, and may be on the verge of becoming parents. They've been trying for a long time, at least in snail years.

Tillie has been here since last summer, and I brought Mike home in April of this year. By the end of April, Tillie had laid her first batch of eggs. Nothing came of them, though. Sometime around June, I scraped them off the wall, hardened and broken, dead.

She laid two more batches, on and behind the pump at the top of the tank, where I could monitor them closely. Nothing happened; they sat there until they shrunk and died. No snails showed up. (The ones I'd found on the beach two years before had one tiny infant snail on them, so I know these should be visible when they hatch.)

The pair kept trying. They like the pump site, and have glued down three more groups of eggs there. Numbers 4 and 5 were duds, too; buttery yellow vases with nothing happening inside.

But the eggs in batch number 6 are alive, growing and moving about inside their little "jugs", and almost out of room. Any time now . . .

Laying the second batch of eggs on the pump, in July.

A few eggs are visible, but they never developed beyond that stage.

Batch number 6, three days ago. One case is smooth and beautiful, but empty. In the others, eggs and darker snails are visible.

When I watch these, I can see movement, but it is so slow that I wonder if it was just my imagination, or my eyes getting tired. But I go away and come back half an hour later, and the babies are in different positions.

Day before yesterday. Compare the positions of the snails and remaining yellow eggs (or yolks?).

Yesterday. There are more dark snails, and they've moved about quite a bit.

And I continue to check on them every hour or so. At the last check, one of the lower cases had a crack in the pointed tip.

While we wait, here are the propective parents:

Mike, on sea lettuce in a bowl.

Tillie, stretching the surface of the water.

Now there's a third snail, the same species, in the tank; slightly smaller, very clean. A youngster. He/she has shown great interest in the egg laying activity, hanging around an inch away, but never attempting to take part. Nor does s/he attempt to mate with either of the other two. It makes me wonder; are these snails monogamous?

So many questions!

Lazy day company

I've been spending these rainy afternoons staring into my aquaria, tracking hermits and clams and anemones, peering behind weeds looking for mating amphipods, watching jellies and worms . . .

Here's a small sampler:

Very small hermit, under an odd-looking seaweed. I've been trying to identify these orange hermits, so far without success.

Eelgrass roots, covered with "gunk", mostly hydroids and detritus, with an amphipod. They love to feed on these messy roots.

Carnivorous snail, Nassa sp., following another up the glass, hoping to mate. When they're done, they'll both drop to the sand and burrow down out of sight again.

Amphipod on rotting seaweed, legs every which way, as usual.

Slipper snails, Crepidula sp., on one of the orange hermits.

The slipper snails are strange critters. Sometimes they sit for months on end in one place; one parked himself on a glass thermometer and stayed there, never moving more than half an inch either way, until I pushed him off to remove the thermometer. Others wander about, now showing up on a rock, now on a shell. They like the hermits, maybe because they are filter feeders, and the hermit is a messy eater.

A slipper snail starts out life as a male. If he finds a handy hermit with no other slippers in residence, he waits until another arrives and climbs on top. Then he undergoes a sex change to become female. All the other snails in a stack are male. They fertilize the eggs of the female on the bottom. When she dies, the male above her becomes female. The female is always the largest one in the stack.*

I have fewer than a dozen slippers (so far), so most of the "stacks" on these hermits are only 2 or 3 deep.

*In contrast, the female hermits are usually smaller; a quite large male will be seen dragging around a mate barely 1/3 his size. Amphipod males are also often much bigger than their mates. Since the other snails in my tanks are hermaphrodites, there is no size difference; each snail is male and female at the same time.

And I didn't have the camera in hand!

My intertidal invertebrates are from a relatively temperate climate, where the water is usually warm enough even for humans to swim. And, being intertidal critters, they tolerate a variable temperature. So with my previous tankful, I set it in an open window; the normal Lower Fraser Valley air temperatures would keep the water in an acceptable range.

But Val, my anemone from Campbell River, is another story. She likes it cold. An average of 56 degrees would be good for her.

Most saltwater aquarists invest in a chiller, a refrigerating unit that cools the water and returns it to the tank. Very nice, needing some maintenance, but what doesn't? But they are expensive! The cheapest is more than the total I've ever spent on the whole setup. And they go on up to over $1000, besides needing a cabinet and a bunch of fittings, making a racket, and being a general nuisance.

So I've gone with the freebie alternative. I've filled a bunch of little plastic cups with fresh aquarium water, and put them in the freezer. Every morning and evening, and several times during the day, I dump some of the saltwater ice in the tank, and refill the cups with aquarium water to go back into the freezer. It takes about 3 to 5 lumps of ice to bring the temperature down to where Val won't go into a sulk.

At first, I would put the ice into the water very carefully, because the hermits would startle at the noise of a splash. They're used to it now. They don't even mind when an ice chunk bumps into them when they're climbing on the eelgrass.

So yesterday, I had dropped in the first two lumps of ice. There were several hermits climbing the eelgrass; no problem. One of the larger hermits made a flying leap onto the ice. His own hermit-sized ice floe! This is living!

Too bad it was melting so quickly; his claws lost traction after a minute, and he slid off the side and tumbled down to the sand.

And, of course, I had my hands full of ice, and the camera on the other side of the room. So you'll just have to imagine it.

To make up for that, here are three more tank pics. No hermit polar bears, though.

Another look at Val's column. She has pasted shells and stones and a lot of gunk all over it. If you look closely at the photo, you'll see an amphipod (bottom right) and, at full size, a number of copepods, some carrying eggs.

Just another Nassa snail, siphon extended, sniffing out his path.

Checking out a possible change of clothes. (He didn't go for it; didn't even try it on.)

These hairy hermits are among the most drab of all the hermit crabs; a dull brownish green, darker antennae with white spots, black eyes, and a hint of blue at the knees. Or so it seemed. This camera does colours so much better! The blue knees are vivid, the carapace patterned in blue-green and gold. And I love the stripy eye stalks! I never noticed those before. (It's worth right-clicking to see this one full-size.)

Tiny discoveries, and a mysterious bubble beastie

One of the anemones was getting itchy feet, wandering about, so I cranked up the camera to take his photo in transit. And got sidetracked by a few things I hadn't seen before.

First, the usual:

Hermit crab, with a tiny frozen shrimp. Nom, nom, nom!

Then, to smaller beasties:

A periwinkle snail. I keep trying to get photos of them eating.  This is the best so far, but a video would be better. 'nother day.

An amphipod, clinging to a blade of eelgrass, legs every which way. There are both green ones and brown in my tank.

Cropped down to show his marvellous compound eyes.

Amphipod eyes are compound as in other arthropods, and sessile, that is, unmovable.  Each eye consists of several hundred individual ommatidia, each of which has its own lens system, light-sensitive retinal cells, nerve leading to an optic ganglion, and each is thought to produce a single image.  Visual fields of adjacent ommatidia overlap, presumably producing good motion detection, but possibly less good resolution . . . it is probably safe to assume that they have good resolution and motion detection, and probably see in colour.  Hallberg et al. 1980 Zoomorphol 94: 279. (From A Snail's Odyssey)

And then I discovered a snail I didn't know was in my tank:

1/8 inch long, climbing on one of the thinnest eelgrass blades. I haven't identified him yet.

Smaller still; I went chasing limpets, to see if I could catch them eating. All around them, the copepods were cavorting:

Female copepod, carrying her egg case at the rear. She has one red eye, in the center of her forehead. (And when she is good, she is very good . . .) About 1 mm. long.

Something half the size of a copepod crawled off a limpet shell and went hiking up the glass wall.

A marine mite, about 0.5 mm.. I found 4 of them, all near limpets. The mess on its right middle leg is made up of diatoms and other debris.

Unlike the few insects and spiders which may be found in marine habitats but must breathe air, mites are able to absorb oxygen from the water so they can live at great depths. (From WallaWalla.edu Halacaridae.)

I didn't know this, so it seemed really weird to see this spider-like thing walking about underwater. It has 4 pairs of legs, like a spider, but holds one pair out in front as if they were antennae. Confusing little beastie.

Some marine mites are phytophagous (suck from plants/algae), some are predators, and some are parasites.

And while I tracked down these mites, with my hand microscope jammed up against the glass wall (and my neck twisted at an impossible angle; they insisted on hanging out on the wrong side of the tank), I noticed many even tinier groupings of bubbles on the glass. This was strange, because I'd scrubbed down the inside wall before I started taking photos. Where did these come from?

Two collections of bubbles and a copepod beside a limpet.

I thought I saw one group of bubbles move, so I zoomed in on it. But no; it was just there, not moving. And just as I was giving up, thinking maybe it was some sort of algae, it suddenly convulsed, waving 4 separate groups of bubbles about, like legs, for a moment, then settling down to rest again.

Other groups I checked showed the same behaviour. They come in different sizes and number of nodes or maybe branches, and they're all over the wall where the light is good, but not on the front (where my neck would be happier) with less direct light.

I haven't the faintest clue what they are. Help!

And I never did get a decent photo of the anemone. And now he's gone and jammed himself into an impossible corner. I hope he doesn't like it there.