So we turned more stones and rocks. Many of them held their smear of jelly, surrounded by snails.
|Tapioca jelly and periwinkle snails. If you look closely, you can see the individual eggs in the jelly mass.|
These snails live only in the upper levels of the beach. They have laid their eggs in shady spots, where they will remain moist, even at low tide, and where they will find just the right mix of algae to eat, once they hatch.
Most of the jellied rocks held more than parent snails, though:
|Three or four different species of snail, and other party-goers.|
The fat, round snails are periwinkles, probably Sitka periwinkles, Littorina sitkana. There are a few Asian mud snails, Batillaria attramentaria, and quite a few small, pointed snails that I think are probably Bittium. Several little Japanese Nassas have come to the feast, too. All but the parents are eating periwinkle eggs.
When I looked closer, at the beach, I found that most of the smaller snail shells held hermit crabs. And when we looked over the photos at home, we saw a pair of flatworms that somehow had escaped our notice, even as we focused the cameras on them.
|Zooming in on the flatworms. Two different species, I think. And three hermits. lower left.|
|Arrows point at a flatworm, a mother periwinkle, and two tiny isopods.|
Twenty seconds later, the flatworms were halfway across the jelly mass, and almost completely hidden. In the clear centre of the jelly, a pair of tiny worms, or maybe isopods are feeding, too.
I brought home two small stones, each with its blob of jelly. When I put them in the tank, the hermits and crabs leapt on them and started cramming big handfuls into their mouths. So much for baby snails, I thought, but this morning, about a quarter of the eggs were still in place, and now they're being ignored; snail caviar is good for a treat, but good old detritus is what sticks to a crab's or hermit's innards.
It seems a waste, really, for a snail to nurture all those thousands of eggs, just so that most of them can be eaten. It's the same with Ma Crab*; a bellyful of berries, which she carefully tends, only to serve as food for barnacles and anemones. But there are a pair of tiny, tiny crabs in the tank, eating and growing rapidly; the lottery winners. The strategy works.
*Turn about's fair play; Ma Crab eats snails' babies, anemones eat hers.
** Quote from snail-caviar.com.