Welcoming committee

For New Year's Day, I posted a photo of a brand new, freshly hatched, pinhead-sized Leafy Hornmouth snail, just starting out on his adventure. This is the backstory.

It started with the small kelp holdfast I brought back from the beach in November. It came with its own cargo of crabs and worms and starfish, but there was a small blank space on the inner side of the clamshell; here, the pair of big snails* in my tank chose to anchor their latest batch of egg cases.

The inner side of the clamshell, as it is today. Much-nibbled-on kelp "roots", and the egg cases at the bottom.

The first of the baby snails started to emerge from the cases a couple of weeks ago. I was on hand to photograph the "birth". So were some other observers, with more ominous intentions.

Three open egg cases. The siphon tip of the latest baby peeks out the exit hole of one.

Several snails hatching at once, at the beginning of the escape. Several egg cases still have their plug in the escape hatch. (Top two on the left, for example.) But look carefully at the background!

Waiting for dinner to be served. Flatworms are always hungry!

There were two flatworms, both very tiny, as flatworms go, humongous in relation to baby snails. One was green; I'd seen it before, but this purplish one has only showed up for the hatching, and has never been seen before or since.

The smallest of the black-clawed crabs, still living in the holdfast.

Against the back wall of the clamshell, too tiny to see without a lens, I found a colony of green anemones. Looking again later, I saw that one had a snail in its mouth.

Watch the holdfast for a couple of minutes, and somewhere among the roots, a worm will poke out his head. There are a dozen or so living here.

Polychaete in his tunnel made of a glued fold in sea lettuce. Tiny, but those jaws will gape as wide as the belly of the beast.

Out searching for food. The tail never leaves the burrow, but he can stretch the full width and height of the holdfast colony.

The brittle stars seem to have disappeared, which would be a relief to the snail parents, if they were of the type to fuss over their offspring. The other two stars have been deported to the shore where they came from, for crimes against snaility. (They were eating the tank cleanup crew; they would have had these babies for appetizers.)

Mortality rates are high in the intertidal zone, especially for the young. One of those egg cases would have started out with about 50 eggs; less than half would survive to hatch. And of the hatchlings, depending on where they emerge and the predator load, anywhere from 50% to 99% will die within the first few weeks.

Observations in San Juan Islands, Washington show that a newly hatched N. lamellosa (Related to my leafies - me) has a 1-2% chance to reach 3mo of age.  An individual reaching 3mo has a 35% chance to reach 1yr of age.  Older, larger, individuals have a 40-60% chance to survive through subsequent years.  Spight 1975 Oikos 26: 9. (From A Snail's Odyssey)

My baby snails, those that made it past the welcoming committee, hurried out of the holdfast to hide in the sand.

On his way.

Zooming in. Siphon to the left, leading the way. Within a few seconds, he had ballooned off the holdfast root, washed away in the current to a "safer" place.

Even out of the holdfast, there are dangers. Hermit crabs. Even the tiny hermit crabs. Shore crabs. Anemones everywhere. Any of these will relish a tender baby snail hors d'oeuvre. The ballooning snail burrowed down into the sand as quickly as he could.

But there are worms down there.

Three times, I've seen a baby on the glass, high above the sand, out of reach of all but the climbing hermits. Good choice. They may survive.

Infant snail, above the water line, surrounded by his own body bubble. Taken through the glass, against the light, which shines through the yellow button at the tip, and shows the ridges on the shell. The dark spot is the operculum, which closes the shell when the snail is resting.

*The parents were Mike and Tillie, Leafy Hornmouth snails (Ceratostoma foliatum). They have since been returned to their home beach, since my visits to the winter shores weren't providing enough juicy barnacles to keep them fed in the tank.

Baby pics!

I've been checking those Leafy Hornmouth egg cases in the aquarium every few hours this week, and finally this afternoon, I saw a dark speck on top. Very tiny; it looked more like a speck of dust, and I left it there. This evening, there were three specks. I fished them out with a paintbrush and looked at them under the microscope, because they were too small to see clearly with only the hand lens.

They are baby snails, still carrying what looks like a bit of yolk, but ready to go out into the wide world.

The egg case is 1 cm. long; the baby snail is about 2.5 mm.

Stretching to turn itself over. I had just returned it to the tank, upside-down.

Two of the babies, out of the tank.

Now, three hours later, another four have emerged, and there are several in the "birth canals", the pointed top ends of the egg cases. More are waiting inside.

The first three have gone on their ways. I don't see them anywhere;it's a big, busy tank, with many hiding places. And many dangers. I hope they have found safe havens.

And meanwhile, Ma and Pa are down on the bottom of the tank, pigging out on a rock full of barnacles that I brought them this Monday.

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!