Foot full of water. With eyes.

 The local aquarium opened for the summer season a week ago. A mini-aquarium, one small room full of large, multi-species tanks, it houses animals and algae collected locally in the spring; they will spend the summer in a safe, comfortable setting, and be returned to their home in the fall.

I spent some time yesterday watching a moon snail plow through the sand.

Moon snail, Neverita lewisii, top view.

This snail is the largest of the moon snail family. This one's shell, visible only in part, is about the size of a baseball. As it moves about, the foot (the soft body, or mantle; it's a monopod, all one foot), flows smoothly over the shell and the sand, sometimes almost completely engulfing the shell.

On the front end (the propodium: pro- in front, podium- foot) there are two sharply-pointed tentacles, sensory organs that detect light and chemicals in the water. Off to the side, there is another structure, like a pipe with a black border on the rim. This is a siphon, which brings in water to flow over the gills between the inner part of the shell and the mantle, where the snail extracts oxygen from the water.

Face to face with the moon snail.

Watching the moon snail spread out, you wonder how it manages to retreat into its shell, or even if this is possible. It is: the foot is full of sinuses, hollow passages where water can be taken in to expand the foot, or expelled to shrink it down to the size of the shell cavity, a separate system from the siphon/gills arrangement. The snail can spread out up to 4 times the width of the shell; that's mostly water.

Rear view. The foot is wrinkled, as it expels some of the water from its foot.

If the snail is threatened, by a voracious sunflower star, for example, it retracts quickly into the shell and snaps shut the door, a flat, semi-transparent shield that fits the opening of the shell. It can't stay this way for long; it can't "breathe" while the siphon is locked inside.

The mouth is on the underside of the foot. Like those of other snails, it has the conveyor belt of sharp teeth, the radula.

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El acuario local abrió sus puertas, empezando su 2023 temporada, la semana pasada. Es un acuario muy pequeñito, apenas un cuarto lleno de tanques grandes; aquí animales y algas nativas, recogidas hace poco en las aguas próximas, pasarán el verano, protegidos y cómodos. En el otoño, los regresarán a los sitios de donde vinieron.

Pasé un rato ayer mirando un caracol luna mientras se deslizaba sobre la arena.

Foto: # 1: El caracol, visto desde arriba. Neverita lewisii.

Este caracol es el más grande de toda la familia de caracoles luna. La concha de ésta, envuelta en la carne (el pie), medía más o menos como un beisbol. El pie (también llamado el manto) fluye sobre la arena y su propia concha suavemente; a veces cubre casi por completo la concha.

En frente (en el propodio, desde pro- frente, podio- pie) lleva dos tentáculos puntiagudos, que son órganos sensoriales, captando la luz y los sabores de sustancias químicas en el agua. A un lado, hay un sifón, que parece un tubito con el borde marcado en negro. Aquí entra agua para pasar sobre las branchias ubicadas entre el manto y la superficie interna de la concha, permitiendo la extracción de oxígeno del agua.

Foto #2: Cara a cara con el caracol.

Viendo como se extiende el caracol, parece difícil que pueda retraerse por completo dentro de la concha. Pero lo logra porque el tejido del pie está lleno de canales llamados senos, donde entra el agua para aumentar el tamaño del pie, o de donde se puede exprimir, para que el animal quepa dentro de la concha. Este sistema no forma parte del sistema del sifón/branquias. El caracol luna se puede extender hasta a 4 veces el diámetro de la concha; la mayor parte de esto es agua.

Foto #3: Visto desde atrás. Se ve arrugada la parte final, de donde se ha exprimido algo del agua.

Si el caracol percibe alguna amenaza, como por ejemplo la estrella girasol, se mete rápidamente dentro de su concha y cierra la puerta, el opérculo, que es una placa semi-transparente del tamaño y forma de la apertura en la concha. No se puede mantener por mucho tiempo así, porque esto también cierra el sifón, impidiendo que el caracol pueda obtener oxígeno.

La boca no se ve en estas fotos; está en la planta del pie, y contiene la rádula con muchos dientes, como otros caracoles marinos.

All that's left

 Sometimes even fragments can be beautiful. I found this center post of a broken moon snail shell on Miracle Beach.

Sun-bleached, sand-scoured.

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Las cosas rotas, hechas pedazos, sin embargo pueden ser hermosas. Encontré este centro de una concha de un caracol "luna", Euspira lewisii, en la playa "Milagro". Está pulida por la arena, blanqueada por los rayos del sol. 

Over the hill

On the back side of the information kiosk on Mitlenatch Island, there were the animals we could hope to see.

Birds, mammals, intertidals, and a snake. Needs its own heading, doesn't it?

Over the top of the hill, we came to the caretakers' cabin. It's a ramshackle, half old lumber, half driftwood, half green walled home away from home. There's a rustic kitchen/storeroom/shower with a half roof, loose plank floor and rough wood shelves. There's an office/study/cold weather room, and a low-ceilinged bedroom. A brisk walk away, there's an open-air outhouse (private, if roofless), and a plastic john for rainy days.

From April to September, two people stay here, a week at a time, to watch for too-enthusiastic visitors and record the changes as the season rolls on. I hear there's a waiting list.

Old moon snail shell, on a tray of dried bones and cracked shells at the gate to the cabin.

One of this week's caretakers, Peggy, met us on the trail and filled us in on the latest news. The gulls on the north cliff were ready to lay their eggs; they should be starting the next day, and the eggs would be hatching in four weeks. On the cliffs over the water, they'd be a bit later. There was a dead seal (I think: my memory fails me here) down below the cabin, slightly nibbled on. She hoped to get permission to study it. And had we seen the tiger lily? (I hadn't; too busy taking photos of something else.)

Showing us the find. 

Camp Bay, from the caretaker's hill. That's the other half of our group in the dinghy, Dave the caretaker on the shore, and Peggy behind him in a blue jacket.

And then we were heading back across the hill to meet the dinghy and trade places with the seal watchers. But first, I had to climb down to a tide pool, take a few fast photos before I scrambled back up the rocks and ran to catch up with the group at the far shore.

The tide was almost in; I didn't see "cucumbers as big as my arm" as per the information kiosk. There were tiny snails, a few small hermits, limpet shells, and hiding in the cracks, a couple of crabs. And three orange-striped green anemones, Diadumene lineata. Made my day; I hadn't seen one of these since Boundary Bay days. The largest one is just below the rock, centre right edge.

I caught up to the group, out of breath, just as the dinghy came in. We boarded, Mike turned her around, and we puttered out to see cormorants and sea lions.

Tomorrow; the sea monsters, finally.

(6th in a series of 9 Mitlenatch Island posts. #1, #2, #3, #4. #5. #6, #7, #8)