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.

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!