Just wondering. No answers.

I look at a beach and I wonder. What shaped it like this? How? And how long did it take?

Sometimes there are answers. Sometimes (usually?) they include words like "maybe", "possibly", "it has been suggested".

Wind, water, ice, (moving or still). Gravity, friction, chemistry, heat, life. And time, lots of time. Or not.

These are photos from one hour on one small stretch of beach. 

At the bottom of the intertidal zone. Soft rock, shaped by waves, currents, colonized by barnacles and oysters.The tip is probably exposed at high tide. This rock is marked on the boating map, labelled "awash rock".

Glacial erratics. Oysters, barnacles, seaweeds. Quadra Island in the background. The current in this channel runs fast and strong and sometimes chaotic.

Wide stripes, running out to the water: rocks, then flat stone or sand, then rocks, then ...

Upper beach, almost flat. Water draining from pools around rocks as the tide goes out carves lines in the sand. (Land to the right here, ocean to the left.)

A bit higher up. The tide is far out, and the sand is almost dry, but water still trickles down from the land above the tidal zone, seeping through the sand.

~~~~~~~~~~~~~~~~

Miro una playa y me pregunto: ¿Qué le dió esta configuración? ¿Cómo? ¿Y cuánto tiempo fue necesario?

A veces hay respuestas. A veces —¿Casi siempre? — las respuestas incluyen palabras como "tal vez", "posiblemente", "se ha sugerido".

El viento, el agua, hielo, tranquilos o en movimiento. La gravedad, la química, la fricción, las temperaturas, la vida. Y tiempo. Mucho tiempo. O no.

estas son fotos que saqué en un tramo pequeño de playa. 

1. Donde termina la zona intermareal. Rocas suaves, esculpidas por las olas, las corrientes, y colonizadas por bálanos y ostiones. La cima probablemente sigue descubierta con la marea alta.  Esta roca está señalada en el mapa para navegantes.
2. Bloques erráticos, dejados por los glaciares.  Ostiones, bálanos, algas marinas. Al otro lado del estrecho se ve la isla Quadra. La corriente en este sitio corre rápido y fuertemente, a veces en forma caótica.
3. Franjas amplias, corriendo en dirección hacia el agua. Piedras, luego roca aplanada o arena, luego rocas, luego ... se repite.
4. En la zona superior de la playa, casi horizontal. Agua que drena desde pozas alrededor de las rocas al salir la marea dibuja lineas en la arena. (Tierra firma queda a la derecha.)
5. Esto está en la parte más alta de la zona intermareal. La marea ha dejado casi seca la arena, pero agua sigue escurriendo, bajando de la tierra firma.

Staying put

The rock dwellers. Not those that live under the rocks, but the brave critters that glue themselves to the rock face, daring the sun to scorch them, freezing or baking winds to sand-blast them. Oysters and barnacles and mussels, and slow-moving limpets. And a few friends.

Oysters, seeming to be part of the rock itself, mussels, barnacles and a  few limpets. And rockweed  and the encrusting stage of a red alga. And one lonely whelk.

One oyster. Note the squeezed-out oyster glue around the bottom of the shell.

Barnacles, the large Thatched Acorn barnacle, Semibalanus cariosus,  and smaller Common Acorn barnacles, Balanus glandulus.

A group of those large barnacles.

An oyster, stuck to its rock, is almost impossible to detach. A barnacle, not so much, although pulling one off kills it, since the base remains on the rock. What is the difference between those two glues, I asked.

(I looked at oyster glue 2 years ago, here.)

Barnacle glue is organic, so is mussel glue. Oyster glue is 90% inorganic. Like the rock itself.

The oyster cement appears to be harder than the substances mussels and barnacles use for sticking to rocks. ... The adhesives produced by mussels and barnacles are mostly made of proteins, but oyster adhesive is about 90 percent calcium carbonate, or chalk. On its own, chalk is not sticky. So the key to oyster adhesion may be a unique combination of this hard, inorganic component with the remaining 10 percent of the material that is protein. (Purdue University) (From my previous post)

Barnacle glues come in two stages.

First stage, as the free-swimming cyprid (baby barnacle) walks around looking for a permanent home:

First, the cyprid releases a temporary adhesive (footprint) for reversible adhesion during surface exploration. (FrontiersInMarineScience)

Barnacle glue has a different chemistry with adhesive protein suspended in an oil-rich lipid matrix. This matrix cleans contaminants from the surface, enabling barnacles to attach to rocks, other sea creatures, ships etc. (asknature)

During surface exploration, the two attachment discs attach and detach from the surface alternatively, allowing the cyprid to “walk” bipedally on the surface. Simultaneously, the cyprid is capable of precisely sensing the biochemical, physicochemical, and topological characteristics of the substrate using an array of antennular setae and chooses to either settle or leave.(Frontiers) 

Then, once a good homestead has been found:

Second, the cyprid produces a permanent adhesive (cyprid cement) for colonization on a suitable site. (Frontiers)

This adult glue is 90% protein. (Compare to the oyster's glue, at 10%.) It has an adhesive strength of 22 - 60 pounds per sq. inch.

Mussels, barnacles, oysters.

So, what about mussel glue? They are almost as hard to remove as barnacles. But they have a different strategy; they tie themselves down with thread. Byssal threads, hair-thin, flexible strands of protein with glue at the tip.

Before it makes byssal threads, a mussel’s foot snakes out of its shell, probing for a suitable place to stick. When the foot is ready to attach, it secretes a series of liquid proteins in a specific sequence, which quickly solidify. Some, mostly collagen (the same protein that makes skin stretchy), become the thin but strong thread itself. Others form a hard protective coating around both the plaque and thread. And just a few of the proteins are adhesive and form the anchoring plaque. (AskNature)

Like the house-hunting barnacles, the mussels use their sticky threads to stroll about. I have watched them in my aquarium; they stretch out a foot, glue a byssal thread down, then shrink back down into the shell, which pulls them close to the attachment point. Stretch out again, send out another thread, glue it down, release the first glued-down thread, and pull. It works. They can work up as much speed as a snail.

Mussel on the aquarium wall, sending out byssal threads, with the fuzzy attachment plaques. Oct. 2022.

To tie themselves down permanently, they send out many threads, intertangling them with those of neighbouring mussels, which gives the bond a strength that can withstand any amount of pounding by waves and even some attacks by predators.

~~~~~~~~~~~~~~~

Los habitantes de las rocas. No los que vive debajo de las rocas, sino los valientes que se adhieren a la faz de la roca, donde los rayos del sol los queman, donde vientos, sea helados o ardientes, los atacan con chorros de arena. Los ostiones, los bálanos, los mejillones, y las lapas, que se mueven tan lentamente.  

    1. Ostiones que parecen haberse integrado a la roca, mejillones, bálanos, y unas pocas lapas. También hay algas pardas, Fucus sp., y la etapa encrustante de un alga roja. 

    2. Un ostión. Se ve un poco del adhesivo alrededor de la base.

    3. Bálanos; Semibalanus cariosus (grande) y Balanus glandulas (chicos)

    4. Un grupo de los bálanos grandes.

Un ostión adherido a su roca es casi imposible de despegar. El bálano, no tanto, aunque separar uno de la roca lo mata, ya que la base permanece en su sitio. ¿Y qué distingue un adhesivo del otro?

(Escribí sobre el cemento de los ostiones hace 2 años, aquí.)

El adhesivo que usan los bálanos es orgánico; también lo es el de los mejillones. El cemento de los ostiones tiene 90% de materia inorgánico, como la roca misma.

El pegamento de los ostiones parece ser más duro que las sustancias que usan los mejillones y bálanos para adherirse a las rocas — dijo. — Los adhesivos producidos por los mejillones y bálanos se componen principalmente de proteínas, pero el pegamento de los ostiones es aproximadamente el 90 por ciento carbonato de calcio, o sea caliza. De por sí, la caliza no es pegajosa. Por lo tanto, la clave que explica la adhesión de los ostiones puede ser una combinación única de esta sustancia dura, inorgánica con el otro 10 por ciento del material que es proteína. (Purdue University)

Los pegamentos de los bálanos son de dos tipos, producidos en dos etapas.

La primera etapa, mientras la larva cipris, un nadador activo, anda (caminando sobre dos "patas") buscando un hogar permanente:

Primeramente, la larva cipris produce un adhesivo temporal (huella) para hacer una adhesión reversible durante la exploración de la superficie. (FrontiersInMarineScience)

El adhesivo de los bálanos tiene una química distinta, con proteina adhesiva suspendida en   una matriz de lípidos. Esta matriz limpia la superficie, quitando sustancias contaminantes, y permitiendo que los bálanos se fijen en las rocas, o en otras criaturas marinas, barcos, etc. (asknature)

Durante la exploración de la superficie, los dos discos adhesivos se adhieren y se separan de la superficie de forma alternativa, permitiendo que la larva cipris "camine" como con dos "patas" sobre la superficie. Al mismo tiempo, la larva cipris puede percibir las características bioquímicas, fisioquímicas, y topológicas del sustrato, usando un conjunto de setas y antenas, y decidir o fijarse o irse.(Frontiers) 

Y cuando se ha descubierto un buen sitio para establecerse:

En segundo lugar, la larva cipris produce un adhesivo permanente (cemento cíprido) para colonizar el sitio apropriado. (Frontiers)

Este cemento del bálano adulto tiene un 90% de proteina. (Comparando: el cemento del ostión tiene solo 10%.) Tiene una fuerza adhesiva de 22 a 60 libras por pulgada cuadrada.

    5. Mejillones, bálanos, y ostiones.

¿Y el adhesivo de los mejillones? ¿De qué consiste? Son casi tan difíciles de despegar como lo son los bálanos. Pero su estrategia es distinta: se atan a la roca con hilos. Bisos, se llaman; fibras finas, flexibles, hechas de proteina y con una placa adhesiva en el extremo. 

Antes de hacer bisos, el pie del mejillón se extiende fuera de la concha, buscando un sitio adecuado donde se puede adherir. Cuando el pie está listo, segrega una serie de proteinas líquidas en una secuencia específica, las cuales se endurecen rapidamente. Algunas, por la mayor parte colágenos (la proteina que hace elástico nuestra piel) forman el hilo delgado pero fuerte. otras hacen una capa protectora y dura que cubre tanto el hilo y la placa.U unas pocas de las proteinas son adhesivas y forman la placa que sirve de ancla. (AskNature)

Como los bálanos en busca de terreno, los mejillones usan los bisos pegajosos para caminar. Los he observado en mi acuario; estiran el pie, fijan un biso en el sustrato, y luego se encogen, retrayendo el pie hasta la concha. Esto tiene el efecto de jalar el animal hacia el punto donde se fijó el biso. Otra vez estiran el pie, extienden otro biso y lo fijan. Sueltan el primer biso  de donde lo adherieron y se encogen de nuevo. ...  Funciona. Pueden "caminar" así tan rápido como los caracoles.

    6. Un mejillón el el vidrio del acuario, extendiendo sus bisos, con las placas adhesivas.

Para atarse permanentemente, producen muchos bisos y los enredan con los bisos de sus vecinos, lo que crea un vínculo que puede aguantar cualquier fuerza de olas y hasta algunos ataques de predadores.

About glues

 When the tide goes out, millions of little scurrying critters go into hiding, under rocks, buried in the sand, under still-damp seaweed. Limpets and chitons clamp themselves tightly to whatever they were travelling on when the water left, usually managing to get into some shade first. Snails slide into cracks and close their doors. The barnacles, the mussels, and the oysters, more than any other of the intertidal animals, have no option but to wait out the dry spell in the open, exposed to the sun and the wind. They can close their shells. But they can't hide; they're glued to the inmovable rock.

Sandstone "sculpture" with oysters.

In my aquarium, I can put a finger on a limpet on the wall and push it to one side. One push; then the limpet snaps itself down to the glass, and cannot be moved. Sheer muscle power!

Oysters and barnacles don't use their muscles to stay put; those are for closing the shell. What they rely on is glue. Their own brand of glue, quick-setting, waterproof, and strong. A barnacle's glue has an adhesive strength of 22 - 60 pounds per sq. inch. If you break off a barnacle (don't!) the animal will die, but its base will remain attached to the rock.

Oyster and barnacles on a rock. Some water still remains.

Oysters are tougher. There's no give to an oyster shell, not even when it's just the left (bottom) valve stuck to a rock after the oyster has died. With a bit of shell, you can scrape the barnacle's base off the rock; not the oyster's.

I looked up oyster glues.

... the cohesive force between the hard substratum and the shell is so strong that a cemented valve can rarely be detached without breaking the shell or the substratum. (Researchgate)

The oyster cement appears to be harder than the substances mussels and barnacles use for sticking to rocks," he said. "The adhesives produced by mussels and barnacles are mostly made of proteins, but oyster adhesive is about 90 percent calcium carbonate, or chalk. On its own, chalk is not sticky. So the key to oyster adhesion may be a unique combination of this hard, inorganic component with the remaining 10 percent of the material that is protein. (Purdue University)

Another few oysters, with barnacles and periwinkles. The red tint is the reflection of my winter jacket.

The glue is deposited only by the left valve, the one on the underside. This valve is deep and holds the living oyster inside. The right valve serves as a lid. 

Oyster and barnacles on a smaller stone. Not a good choice; this rock can roll.

First, tiny glands lay down a web of protein fibers. Next, they release a calcium paste onto the web, and it hardens like plaster. (ShapeOfLife)

"It hardens like plaster." Underwater!

~~~~~~~~~~~~~~~~~~~~~~~

Cuando baja la marea millones de criaturas se apuran a esconderse, ya sea en la sombra de las rocas, ya sea bajo la arena, o cubiertas de algas marinas que todavía siguen húmedas. Las lapas y los quitones se adhieren fuertemente a la superficie donde andaban cuando les faltó el agua; si pueden, se buscan un poco de sombra primero. Los caracoles se esconden en grietas y cierran sus puertitas. Los bálanos, los mejillones, y los ostiones, más que cualquier de los otros animales de la intramarea, no tienen otra cosa más que aguantar la sequía sin protección del sol ni del viento secador. Pueden cerrar sus valvas. Pero no se pueden esconder; están cimentados en la roca inmóvil.

Foto #1: Una "escultura" de piedra arenisca, con ostiones.

En mi acuario, puedo poner el dedo en una lapa en la pared y moverla. Una vez. Y entonces la lapa se aprieta contra el vidrio y no se puede moverla sin matarla. ¡Fuerza muscular!

Los ostiones y los bálanos no usan los músculos para mantenerse fijos en su lugar; los músculos sirven para cerrar las valvas. Lo que usan es pegamento. Su propia marca de pegamento, de endurecimiento rápido, impermeable, y fuerte.El pegamento del bálano tiene una fuerza adhesiva desde 22 a 60 libras por cada pulgada cuadrada. Si rompes un bálano (pero no lo hagas) el animalito se morirá, pero su base permanecerá adherida a la roca.

Foto #2: Ostion y bálanos en una roca, con un poco de agua.

Los ostiones son más fuertes. No hay movimiento posible en la concha de un ostión, ni siquiera cuando todo lo que queda es la valva inferior cuando el animal ya desapareció. Con un pedazo de concha, puedes quitar la base de un bálano de la roca; no la valva inferior entera de un ostión.

Busqué los pegamentos de ostiones en el internet.

... la fuerza cohesiva entre el sustrato duro y la concha es tan fuerte que una valva cimentada raras veces se puede separar sin romper o la concha o el sustrato. (ResearchGate)

El pegamento de los ostiones parece ser más duro que las sustancias que usan los mejillones y bálanos para adherirse a las rocas — dijo. — Los adhesivos producidos por los mejillones y bálanos se componen principalmente de proteínas, pero el pegamento de los ostiones es aproximadamente el 90 por ciento carbonato de calcio, o sea caliza. De por sí, la caliza no es pegajosa. Por lo tanto, la clave que explica la adhesión de los ostiones puede ser una combinación única de esta sustancia dura, inorgánica con el otro 10 por ciento del material que es proteína. (Purdue University)

Foto #3: Algunos ostiones con bálanos y caracoles.

El pegamento es depositado por la valva inferior; esta valva es honda y aquí vive el animal. La valva superior funciona como tapa. 

Foto #4: Ostión y bálanos en un piedra chica. No fue una buena selección; la roca puede rodarse.

Primero, glándulas pequeñas producen una red de fibras de proteínas. Luego, sueltan una pasta de calcio encima de la red, y ésta se endurece como si fuera yeso. (ShapeOfLife)

"Se endurece como el yeso." ¡Y eso, bajo el agua!

Stacked critters at lunch

Hermit crab, snails, and oyster:

The hermit is eating his lunch, a shrimp and veggies pellet.

And beneath, the oyster opens wide, ready to catch any fine crumbs.

These pellets, a favourite with the hermits and crabs, contain: krill, fish, shrimp, soy (not a "normal" hermit diet, is it?), wheat, corn meal, squid meal, yeast, kelp, dried seaweed, more fish meal and oil, turmeric (for an appetizing colour or to make the grains taste like real food?), MSG, and assorted vitamins.

The anemones accept these readily, but soon spit out an orangey mush. They like plain dried shrimp better.

Some of the scavenging snails eat the leftovers. There are plenty; the hermits are messy eaters, and easily distracted by another hermit with an apparently bigger pellet; these must necessarily be chased down and captured immediately.

Worm caves and oyster grins

I bought an old abalone shell in a garage sale for a buck, 11 years ago. It sat on a shelf until I decided to use it in the aquarium as a hermit crab gym set. It has been very popular. The plumose anemone has chosen it as her permanent base, worms have built their tubes on the back, limpets sleep on the shiny floor, and the hermits still climb to the top to look at the world.

Over these ten years, much of the shell has dissolved into the water, and assorted algae have coated the rough outer side, creating interesting patterns. And colonies of tiny worms have made their homes in the pores, by now eroded into deep caves.

Outer rim of abalone shell, with algae and worms

Abalone shell, before being tanked, 2007. The outer shell is porous. The barnacle and tubeworm remains dissolved long ago.

The oyster, picked up on the beach after a storm, has been here only a few months. The shell was scrubbed white by wind and waves, but tank algae are at work here, too. And the oyster, not in the least fazed, is grinning.

Toothy grins

The oyster is a filter feeder, and pumps large volumes of water in, over the gills, where edibles are caught in mucus and moved down to the mouth.  What looks like teeth in those smiles are tiny tentacles. The gills are just behind them, sometimes visible when the oyster opens a bit wider.

Smile!

Oysters do.

Toothy, clownish smile.

Oysters are filter feeders. They "inhale" water, pumping it over their short tentacles and their gills, trapping small particles and swimmers in mucus, which they pass on to the mouth. The "teeth" in this photo are tentacles. The gills are right behind them.

Oyster anatomy. Gif from East Hampton Aquaculture.

The food travels through the stomach and intestine. What is rejected out of hand, before it enters the intestine, such as bits of sand, is wrapped in mucus and expelled, much as we spit out fish bones without swallowing them. Of the rest, indigestible food particles travel through the digestive system, and are also expelled into the surrounding water, where the busy janitors (aka hermit crabs) collect them and reprocess them.

An oyster can filter up to 5 l (1.3 US gal) of water per hour. ... Excess sediment, nutrients, and algae ... Oyster filtration can mitigate these pollutants. (Wikipedia)

So the three oysters now in my tank may be filtering 15 litres of the water every hour, 180 litres a day. The anemones will be happy; they hate polluted water.

Unexpected guests

I was hunting for barnacles. My leafy hornmouth snails were hungry, and that's all they would eat. And I wasn't having any luck. I walked miles down the shore, over several days, finding nothing. Not a barnacle in sight, except on huge rocks. At the higher tide levels, they don't like small stones that can be rolled around by the waves, crushing their shells. For critters with only feet and an intestine, they're remarkably smart.

Last Saturday, I was out searching again. Nothing, nothing, nothing. I gave up and started walking at the extreme high tide line, where seaweeds and bits of driftwood tossed up by the recent stormy weather were drying. And there, far above their normal haunts, I found three large oysters, covered in barnacles.

They had to be dead by now, cast up this far above the usual water line for several days. But the barnacles would be ok, and I could open up the oysters, scrape them out, and put the clean shells with their load of snail food into the tank. I brought them home.

Except that they weren't dead. When I put them in water to wash them off, they opened up. When I touched them, they closed down. Alive and healthy; they're hardier than I imagined.

Oysters in the aquarium. With happy leafy hornmouth snails and hermits.

The snails got busy right away, eating several big barnacles each every day. And the scavengers, hermits and crabs, swarmed over the shells, picking away all the rotting seaweed, cleaning out dying barnacles. (The snails won't touch those: they like their meals very fresh.) The oysters pumped water in and out as the hermits cleaned off their lips.

Under the detritus, the hermits discovered a couple of anemones, looking miserable, shut down and fraying. The hermits took over, tearing away all the dead flesh, cleaning out the wounds. A day later, the anemones were as good as new.

Anemone # 2. Looking good. Smaller than a barnacle. Pink-tipped anemone, Anthopleura elegantissima, maybe.

Yesterday's anemone, once the minor surgery was finished, went for a walk and ended up parked on one of the snails. In the top photo, above, it's on the snail on the right.

While I was at it, I took a few more photos of the warty tunicate (the orange tubes in front of the oysters above). It has also been thoroughly cleaned by the hermits; they're busy little beasties.

Warty tunicate, Pyura haustor, showing the "warts", now that the old gunk is gone.

Zooming in on one siphon. It looks like a smaller tunicate is growing there.

Yellowlegs and oysters

At the mouth of the Nicomekl River, where it empties into Boundary Bay, the native Olympia oysters line the shores and pile up in shallow water. A discarded tire serves as a handy anchor point.

The water here is knee-deep to the long-legged yellowlegs.

The presence of a hard substrate or anchor surface is a key component to colony development, in conjunction with other suitable features such as flushing flows and adequate nutrients and food organisms. ...
Larval oysters tend to affix to the undersides of horizontal surfaces. The young oyster (“spat”) crawls with the foot along the surface of substrate and secretes glue from a “byssus” gland, which attaches the shell to the substrate.  (From Ibis, UBC)

The Greater yellowlegs was wading back and forth in the clear water, looking for food, and occasionally calling loudly. (Listen to his call here; the last of the alarm calls.) There were no other birds to be seen.

Hunting, hunting ... There's gotta be a fish here, somewhere.

Zooming in on the yellowlegs.

When I see one alone, it's hard to tell which it is; Greater or Lesser? Unless they're side by side, they look and act alike. And both species are likely to be found at this end of the Nikomekl.

The two yellowlegs species are very similar. Size is marked different when they appear together and can be compared against each other. Greater Yellowlegs's bill appears slightly upturned and blunt-tipped, while Lesser Yellowlegs's bill is straight and sharp-pointed. Lesser's bill is always dark, while Greater's bill is grayish at the base in nonbreeding season. Voice is best distinguishing character: Greater gives three or four piercing notes, Lesser two rapid, softer short whistles (sometimes or or three). (From Cornell Lab of Ornithology.)

Just missed!

. . . and other glitches.

The walk under the trees was peaceful; out on the wetlands, the sun was warm. The weather was glorious, with a clear blue sky and pillows of white clouds on the mountain tops. Sparrows and robins sang in the weeds, thousands of bees buzzed in the lupins waving blue and pink flags on every hill. Cottonwood fluff drifted in the wind and speckled the pools and river. Just simply delightful!

There had to be a fly in that ointment. There was.

On the first leg of the path, grasshoppers popped up from under our feet, waved butterfly wings at us for a second or two, then settled to become invisible again. We stalked them with the cameras. They were too quick for us. The best I got was one shot, where I didn't even give the camera time to focus.

I've sent this to BugGuide for an ID. I'm stumped. Update: It's a Mourning Cloak butterfly, badly frayed. Thanks, Bug Guide people!

Oh, well; grasshoppers are like that. (Update: So are butterflies.) On! Between the trees we could see the boats moored on the Nicomekl river, and the mud flats adjoining, where once we saw flocks of sandpipers sleeping in the grass at the edge. We walked down a little trail to get a good look. No sandpipers. Not even a hint of one. No ducks, either.

But there were oysters. Piles of them, exposed at low tide.

Big guys with frilled edges

They cling to any anchor point in that sloppy mud.

I took it for granted that these were the native oysters that have been living in the Nicomekl for centuries, but didn't risk the mud to go and get a good look. But they're far too big; the natives are barely a couple of inches long, and these are as big as my hand. And they mound up on top of each other, rather than hiding under rocks.

As far as I can tell from the photos, they're the imported and invasive Japanese oysters.

Crassostrea gigas is an estuarine species, but can also be found in intertidal and subtidal zones. They prefer to attach to hard or rocky surfaces in shallow or sheltered waters up to 40 m deep, but have been known to attach to muddy or sandy areas when the preferred habitat is scarce. The Pacific oyster can also be found on the shells of other animals. Larvae often settle on the shell of adults, and great masses of oysters can grow together to form oyster reefs. (Wikipedia)

In some places in the world, though, it is considered by some to be an invasive species, where it is outcompeting native species, such as the Olympia oyster in Puget Sound, Washington . . .

... and here just across the border.

Around the corner, we stopped to take photos of the bees in the thimbleberry bushes, then looked over the pool on the inland side of the trail. Nothing in the grass, nothing on the water. We went on, and a minute or two later, stepped aside to let another walker pass.

"I just saw a fox in the grass back there!" she said, pointing at the fence we had just been leaning on. "It was so shiny!"

I kept looking for the fox the rest of the time. It never showed.

But we saw ducklings; 7 of them:

Way over there against the bank. See them? (I darkened them a bit to make them visible.)

We turned inland at the bridge, to walk back across the wetlands. On the bridge rail, a chipping sparrow was sitting, chipping away merrily. At least we saw him; all the photos show is a vaguely bird-shaped grey-brown splotch.

On the bridge, I was looking over the rail at the mud under the roots of the cattails. Laurie was a way back, trying unsuccessfully to take photos of the redwing blackbirds. Down in the muck, I heard a bird call, one I didn't remember hearing before. And there was a bird down there, a dark brown bird-shaped thing scooting away into the vegetation. I could hear his call, then, as he wandered around in the reeds, but I never saw him again. Nor did Laurie, when he came to help me look.

Looking through the books, I think -- I think -- that it's possibly a Wilson's snipe. A life bird! If you can count a one-second sighting.

On the trail through the grassy field, we passed the barn owl house. I had no hopes of seeing one; they would be sleeping, but still, I did entertain the thought that one might have thought of a mid-afternoon snack. Of course not!

And we passed the tree where, a few years back, a huge wasp nest had hung from an upper branch, like some kind of weird grey strawberry. I looked, but there were none in the tree now. On the home stretch, though, we walked under a broken red alder. In the gap where the wood had torn, there was an abandoned wasp nest, very tiny. I found a long stick and poked it out.

Looking almost straight up.

Very small. Lots of space inside; you can see the inner wall through the gap.

Another view, showing the cells. I can count 6; there are probably a couple of dozen in all. Their entry hole is at the right.

Thinking it over: missed shots, missed sightings and all; it was all wonderful.

And there were still the lupins. And their cloud of bees! (Photos of these, anon.)

(Someone thought I should make the photos larger. I'm trying that, to see how it looks.)

There's always something new.

I always thought oysters were white. Or maybe greyish. But after I've looked at every other possibility, I think this is an oyster.

Beautiful colours; burgundy, cream, and whitest white.

The black, stripy thing is a small mussel, attached. The large shell is attached to the rock.

This was on a low rock about halfway down the intertidal zone. It's small, for an oyster; about 2 to 2.5 inches long. We only saw the one. I've seen a few, very few, oysters in the sand on White Rock beach before, but they were all white.