Empty shells

From my tank:

All that's left of my bubble shell snails

Bubble shells thrive in my tank, in season and out. They go on mating and laying more and more egg masses all winter and well into the spring. But eventually they get tired, they get careless and let the current take them where it will; right into the hungry maw of the big anemone. A day later, she spits out the empty shell, and if I find it before it's crushed, I save it, just because it's beautiful.

And from various beaches:

Assorted clam shells. I can't resist collecting these miniatures.

The pink shells are Macomas, mostly from Boundary Bay and Iona Beach. The yellow ones, also Macomas, are rarer; I found these at Iona Beach, where there were vast numbers tossed up on the sand just above the tide line.

They are as delicate as they look. The stained one, beneath, is a different species.

Busy bubbles

There are three bubble shell snails in my tank. They're doing their best to turn that into thirty. Or three hundred.

Lone bubble shell, Haminoea japonica. Belly view, through glass.

Two bubble shells. The one in back has been following the other's slime trail from the far side of the tank, and is about to catch up.

At last! And the two slipped under the sand together, to indulge in their favourite pastime.

These snails are hermaphroditic; at each mating, one takes on the male role, the other acts as the female. The next time round, they may switch. And both are capable of laying eggs.

Their second favourite pastime. Laying eggs.

The eggs are expelled through a genital pore just behind the head. Each yellow egg is encased in a tramsparent jelly capsule, that is just barely visible in these photos.

As she lays the eggs, she curls away, leaving a crescent shaped jelly mass glued to whatever surface she has chosen (in this case the front glass wall of the tank.)

I'd never seen a bubble snail's mouth before; it's usually completely shrouded by the head shield and the lower foot.

The eggs should hatch in about a month. Unfortunately for the bubble's plans of conquest, the infants don't survive in the tank. They're probably swept up by the pump within hours of hatching.

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!

Busy bubbles

A family of bubble shell snails came home on the last batch of eelgrass; 2 adults and 4 tiny ones, still just wriggly brown balls. Two of those got lost, eaten, or crushed, but the other two are now full-size.

And they're all working on re-populating the tank. I keep seeing couples twisted together; later, almost every day, there's a new batch of eggs, some on the remaining eelgrass, but mostly on the glass wall.

Bubble shell underside, on glass wall. Cream and grey, with egg-yolk internal shell.

The largest of the bubble shells. This one has dots of orange on his back, and a dark rear end.

One of the egg masses, a transparent jelly with almost white eggs arranged in a rough spiral.

Smaller bubble shell, with new egg mass. It looks like his inner shell was cracked at some time, although he has recovered. The shells are paper-thin, and brittle.

The egg masses gradually disintegrate over a week or so. Looking at a mass a few days old through the microscope, I can see each individual egg; a solid centre surrounded by its own transparent container. Most of these will be spinning around, slowly the first few days, but more rapidly as they develop.

I haven't seen any new babies crawling about, though. It is possible that they get dragged into the filter and destroyed.

A bubble in the hand . . .

is worth any number in the eelgrass.

It's interesting, how once you've gotten familiar with the shape and movements of a critter, that you see them in places where you looked before, without finding any. Like the bubble shell snails; I've waded knee-deep in the eelgrass beds at low tide in Boundary Bay many times, and all I saw were crabs and isopods. This last time, I recognized the bubble shells, dozens of them.

They're easy to catch; they hang out on the eelgrass blades, and when they're disturbed, they just let go and float down to the next blade. And they're just as content to land on my hand.

I got this one still on his eelgrass. He's upside-down, twisting up to get a look at me.

Setting out to explore. Isn't he a cutie?

"Hi, there!"

These snails are incredibly fragile; their shells are paper-thin, and as brittle as eggshell porcelain. Other snails have thick, sturdy shells, essential for survival in crab country. Even so, I find many empty shells, peeled back by crabs to get at the tasty meat inside. How do the bubble shells, without that protection, manage to live?

Watching them on the eelgrass, it all became clear. As long as the eelgrass in underwater, it stands upright, swaying in the current. The crabs scuttle along underneath, but only the smallest climb the eelgrass; it won't support the weight of the larger ones. Up at the top of the bed, there are no hard edges, no stones, no crabs, nothing to squeeze or bang those fragile shells.

When a bubble shell drops to the sand, he buries himself immediately. I've been watching in my tank, as they just ooze down between the sand grains and disappear, in seconds. The next time I see them, they're climbing an eelgrass stalk, up to safety.

Bubble shell egg ribbon, on eelgrass

I have seen these egg ribbons many times, but didn't know which snails they belonged to. Now I do: I've watched the bubble shells laying them, gluing them to the eelgrass blades near the top of my tank.

There must be thousands of eggs in one ribbon, and a bubble shell will lay several ribbons over the course of a few days. Few of them survive, or we'd be wading through a mass of bubble shells. Hermit crabs love them; fish eat them, so do nudibranchs. Even in the gentle eelgrass beds, life is precarious.

Hearts in bubbles

From the Merriam-Webster dictionary:

Ham·i·noea noun \ˌhaməˈnēə\
Definition of HAMINOEA
: a common genus of bubble shells (family Akeridae) of the Pacific coast of No. America with a shell so thin that the pulsation of the heart of the translucent yellowish brown animal within is commonly visible through it.

I've got three new bubble shells in the aquarium, and they're big enough (over an inch long) for me to see this. And they hang out near the water surface, so I've got video, too!

Cool, eh?

All cracked up, and pooping

It all started with Val, the anemone. Beautiful though she is, she's deadly. All tentacle, mouth and stomach, and no mind, she sits in her corner where the water currents are strongest, tentacles waving merrily. Waiting. Sooner or later, something falls off the wall into her open maw, and the tentacles close in quickly, trapping and stinging the unfortunate wall cleaner. A minute later, it has disappeared into her stomach, and she spreads out her empty net again. The snail (and it's usually a snail) eventually reappears as an empty shell, ready for occupancy by a growing hermit crab.

Val, just beginning to open up after a meal. With a leftover snail shell.

The two bubbleshells were part of the crew of glass scrubbers. They wandered around happily, eating algae, mating, laying more eggs every day. Then one, the big one I called Hammy II, disappeared. Sir Ham, the smaller one, moped for a bit, then went back to work. I kept a close watch.

Then, a few days ago, I was just in time to see Sir Ham, all curled up, caught in Val's tentacles. I quickly reached in and flicked him out with a fingertip. (Val was not pleased; she sulked for hours.)

The bubbleshell was still moving when I moved him to a bowl of water. Barely moving. I needed a lens to see it. I was sure he would die, but I set him up in a "hospital tank", with fresh water and a protective covering of sea lettuce, and kept an eye on him.

Hours later, when I was going to bed, he was almost black, curled up tightly, not moving at all until I touched him gently. I left him overnight in the fridge; warm water would stress him even more. And he was still alive in the morning! I was surprised; he even seemed to be starting to stretch out a bit.

For three days, he hovered between life and death, but last night, he looked at the sea lettuce and found it interesting. And this morning, when I looked, this is what I found:

A trail of bubbleshell poop!

Sir Ham is eating again!

This evening, when I changed the water, it was full of little poopy pellets. Good on you, Sir Ham!

Sir Ham, convalescing.

But look at his photo now: The shell is cracked and scored. It wasn't before. I'm starting to wonder if maybe the largest crab hadn't tried to split it open to get at the delicious bubble meat inside. And maybe that's why Sir Ham wasn't strong enough to resist the current any more, and fell into the anemone's mouth. Predation in tandem: not fair!

So there he stays, for now, in the hospital tank, while I decide what's to be done. Return him to life as it is, dangers and all, or provide safer housing in a corner of the tank? And I need to find him a new mate; don't those eyes look lonely?

(Cleaning the tank, I found Hammy the Second's shell, all cleaned out. So he probably met the same fate, but without a rescuer handy.)

Caught in the act!

Update on Bubbles in Love.

The hermits have been eating the egg ribbons. I caught one of them at it this afternoon, and there were no more to be found. But tonight, Hammy II laid another ribbon.

Egg ribbon on sea lettuce. Slime and bubbles.

H/she laid the eggs, attached to that brown fragment of eelgrass at one end. The last thing h/she did was to glue the whole thing flat against the sea lettuce.

(Poor photo; no time: I have to catch a plane.)

Bubbles in love

On a wide, flat beach, small animals seek shelter wherever they can get it. Under the eelgrass, in burrows, on the sides of waterlogged wood, under rocks; or in populated areas, under and around human artifacts, trash, boats, anchors, bottles. One favourite hiding place is an abandoned clam shell, the bigger and more solid, the better.

At low tide, I keep an eye peeled for large shells, especially the older, seaweed-encrusted, barnacle-thickened ones. I look inside each one; no telling what I may find. Sometimes it's a scale worm or two. A couple of weeks ago, it was a collection of those little, unidentified egg casings.

Scale worm, 1 cm. long.

Egg cases. I've seen them identified recently, but can't remember where. UPDATE: Possibly the Leafy Hornmouth, Ceratostoma foliatum.

On our last visit to Boundary Bay, 'way out near the bottom of the intertidal zone, a clamshell I collected had a live bubble shell snail inside. I didn't have a container big enough for the shell, and in a plastic bag, the critter would dry out, so I walked back towards shore, carrying this clam shell half full of water. But it leaked; there must have been a crack somewhere. So at every little pool, I stopped to fill the shell again. I needed some better way to keep it wet.

When we reached another tide pool full of eelgrass, I dug out several plants, roots, a handful of sand each, and all, and stuffed it all into a plastic bag. I carefully put the clamshell and bubble snail on top, and covered it with more eelgrass, dripping wet. That should hold it.

And my last handful of eelgrass roots and sand came up with a second bubble snail. Two in a day! It went into the bag to keep the first one company.

Hammy the second, at home in a plastic cup. Love the eyes!

They both made it home ok, and made themselves at home in the tank right away. They are not like the previous one I had, a Haminoea japonica (I think); it spent most of its time in the sand. This pair wanders around on the eelgrass, and often on the glass walls of the aquarium.

Belly view, just under the water surface. With a grazing snail. (See the little pink mouth.)

These two are a native species, Haminoea vesicula, the white bubble snail. They are eating the algae off the inside of the walls, and probably off the eelgrass. When they have been knocked off onto the sand, they usually head straight for a wall and go on up. They move quite rapidly, for a snail.

Hammy the Third (aka Sir Ham), the smaller of the pair, checking out the big world above the waterline. He looks like some fat owl in a waistcoat. The round "belly" is his shell, and the flesh folds over it.

I can always find one of these if they're somewhere on a wall, because they leave a slime trail behind themselves. It catches bubbles from moving water, marking their path for several hours.

A couple of inches of slime trail, with bubbles.

I had tracked Hammy II to a spot on the front wall, and went looking for Sir Ham. I found him at the beginning of Hammy's trail, hurrying along it, staying with it, like a bloodhound on a scent. When he ran into a gap where a snail had broken the string, he cast about, up and down, until he found it again.

When I checked back, the two were together, doing what snails do in the springtime.

Hammy II above, Sir Ham below. And an intrusive periwinkle. Ignore that; the bubble shells certainly are.

They twist around some. At one point, HII was floating free, except where he held onto Sir H. Slime swirled around. This I couldn't get on camera, but towards the end, a long, thick cord dangled down below them, several inches long. When they left to go about their separate ways, it stayed behind, and gradually dissipated in the current.

And the next morning, this is what I found on the eelgrass:

Ribbon of eggs. Thousands of eggs, it seems.

This helps to identify the bubble shell; each species makes a different egg mass.

And the next day, they mated again. This morning, there is a new egg ribbon. This afternoon, they were back together. Busy little beasties. I'll be looking for eggs again tomorrow. I wonder if any will survive to grow into new little Hammies.

These snails are hermaphrodites, so both can lay eggs. I don't know who is responsible for the eggs they've laid so far.

Bubble wrap critter

When I was a kid, I used to sit for hours on the beach, sifting sand, looking for miniature shells. Tiny mussels, snails, Baltic macomas in pink and yellow, dime-sized sand dollars, little stripy clams, limpets with chimney holes: I loved them all, and always went home with a pocketful.

I don't sit on the beach any more, but I still keep an eye out for the delicate mini-shells. Pretty clams turn up on the White Rock beach, macomas at Iona Beach, periwinkles on Crescent Beach. At Boundary Bay, besides the ever-present mud snails and big broken clams, the remainders of gull dinners, I don't see many others. Occasionally, I find a few pink macomas or a sharply-pointed snail shell. And rarely, maybe three times in all the years I've been looking, I find a bubble shell.

Probably Haminoea vesicula. Very thin, extremely fragile, translucent, and so light I could blow it away. This one is 7 mm long.

Underside. Or rather, inside bottom.

In spring and summer, they say the animal itself can be found in beds of sea lettuce and eelgrass. I had never seen it. And the rest of the year, it may as well be invisible; it blends in perfectly with the sand.

I found an oval bubble shell (the animal, not the shell) in a bag of eelgrass and sea lettuce that I brought home for my hermits. When I washed the veggies, a tiny slug-like thing oozed out and across the bottom of my bowl.

Haminoea japonica, top view. About 3/4 inch long, stretched out.

This is a mollusc, related to the aglaja that I found last year. Here's a mouthful:

it's "a marine opisthobranch gastropod mollusc in the family Haminoeidae" (Wikipedia)

Opisthobranch means "gills behind" (and to the right of the heart). ... Opisthobranchs are characterized by two pairs of tentacles and a single gill behind and to the right of the heart. (Wikipedia, again)

I didn't see the tentacles, unless they are those two little protrusions on the sides of the head. It's hard to tell, because of the unusual head: the oval bubble shell is distinguished by hir forked head shield, like a flat helmet. And the front of the foot is flattened out underneath this shield, making it look from the side as if the animal had fat lips.

"Mouth" closed.

"Mouth" open. I think those two black dots are eyes.

Unlike the sea slugs, Hammy has a shell. But the flesh of the foot folds up around the outside of the shell, in two wings over the sides, and a smaller cover at the tail end. I took these photos as s/he slid across a piece of sand dollar; on the sand, the spotted body blends in so perfectly that only the top of the shell can be seen. Once it reaches the sand, s/he buries hirself quickly, in a few seconds.

Fully stretched out, crawling up the glass wall of the aquarium. The underside. The shell is visible, but encased in flesh. Head at the top, tail end floating free. A minute later, s/he let go, floated to the sand, and disappeared.

This bubble shell eats vegetation, like the sea lettuce and sea hair algae, as well as diatoms. (The aglaja, hir cousin, is a carnivore, and eats bubble shells.) S/he also eats sand, which can be found in hir gizzard. (And I thought only birds had gizzards!)

As s/he travels along, s/he leaves a trail of slime, which possibly may serve to guide other bubble shells to hir location. I noticed this when s/he climbed up the glass wall; behind hir, a string of tiny bubbles caught the light.

This whole sub-class, the Opisthobranchia, boasts some of the strangest animals in the ocean. It includes the nudibranchs, with their amazing colours and imaginative body shapes, the "flying" sea angel, the winged slug, the stomach wing, the sacoglossa sapsuckers, that look more like scraps of rag than animals. (This page has some of our local specimens Or see National Geographic's photos of nudis. Unbelievable!.)

"Hammy" at least looks sensible, but s/he has hidden talents. The bubble shells are hermaphroditic; each one is both male and female. After mating, s/he lays the eggs in small, yellow, sausage-shaped clumps, from 300 to 700 yoked eggs in each.

So far, this is unsurprising. But then, the some of the eggs hatch into tiny swimming veligers, free-living. These go through several stages, out on their own in the water, not eating, but risking being eaten, before they mature and settle down to a slug shape.

Veliger of a sea hare, a relative of Haminoea. 50 nanometres. Wikipedia.

Other eggs wait to hatch until they are mature, crawling little bubble shells. (CIESM Atlas) There are advantages to both strategies; the veligers get to populate new territory, while the homebodies are safer.

Haminoea vesicula (the empty shell above) is a native: H. japonica is an import from Japan, previously known there as H. callidegenita. It has now spread worldwide. It doesn't seem to be invasive, but may be carrying the organism that causes swimmer's itch. Carry a towel!