Biodiverse, very biodiverse

 We have some beautiful low tides coming up, but they're going to arrive here after dark. (Sunset these days falls around 7::30 PM.) I followed the tide as it started out in the late afternoon, and found anemones, feeding happily, then closing down as the water disappeared.

Window into a tide pool.

The surface of the water in the tide pool reflected the sky, but the shadow of my head revealed a pink-tipped green anemone, Anthopleura elegantissima, fully open. With it in this little tide pool are several rockweeds, and three red algae; a feathery, delicate one, a narrow-bladed species, and a broad blade; the white algae is a red that has been sun-bleached. On the right are strands of the brown Sargassum. And there are several fragments of the green sea lettuce, Ulva spp. Also present: periwinkle snails, limpets, and something orange, probably a sponge. And unseen, but always there in great numbers: the worms. And a clam on the sand nearby was spitting at me.

 

Still underwater, still waving those tentacles.

The colours of this anemone vary; the tips go from barely pink to red. The columns and the oral disc are sometimes bright green, in others they may be more of a yellowish cream. The green colour is usually due to the presence of single-celled green algae, but the anemone may also produce its own colour. The green algae are photosynthetic and provide a large part of the anemone's energy needs.

"Although the green colour present in some specimens is produced by the animals themselves, this process can only occur when the unicellular symbiotic alga Chorella is residing in their tissues." (Marine Life of the Pacific Northwest)

The lichens aren't the only composite species.

Very pink. The column is always covered by rows of tubercules, seen here as pale green bumps.

As the water recedes, the anemones start to shut down.

Edge zone; open tentacles on the right, closing, closed out of water.

And when the water is gone, they turn into yellowish donuts with cherry filling.

These anemones grow on rock. The sand has collected around them. As the sand dries, they will all shrink back to their base, and disappear from the surface, leaving only slight depressions. Until the tide comes in.

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En esta temporada, nos llegan unas buenas mareas bajísimas, pero (mala suerte) por este rumbo, la bajamar toca ya bien puesto el sol (que desaparece a las siete y media). A media tarde llegué a la playa y seguí el agua mientras se retiraba, encontrando unas anémonas, contentas con los tentáculos abiertos mientras había agua, y luego encogiéndose cuando se iba.

Foto #1: Una vista en un pocito mareal. La luz se reflejaba en la superficie del agua, pero mi sombra abrió una ventanilla, mostrando una anémona clonal, Anthopleura elegantissima, y varias algas. Se ven aquí, primero Fucus gardneri, luego tres algas rojas: una delicada, una de una hoja larga, y otra de hoja ancha. Las algas blancas son algas rojas quemadas por el sol. A la derecha hay varios hilos de Sargassum muticum, un alga marrón, invasiva. Y luego pedazos del alga verde que llamamos lechuga marina, Ulva spp. ¡Hay más! Varios caracolillos, unas lapas, y unas masas anaranjadas, probablemente esponjas. Y no se ven, pero los hay en gran número; los gusanos de varias especies. Y al lado del pocito mareal, una almeja me estaba escupiendo.

 Foto #2: Varias anémonas, todavía bajo agua, todavía agitando sus tentáculos.

Los colores de estas anémonas son variables; las puntas de los tentáculos van desde color de rosa hasta rojo fuerte. Las columnas y el disco oral son verdes, a veces brillante, a veces pálido. El color verde se debe a la presencia de algas unicelulares verdes, aunque a veces la anémona puede producir su propio color. Las algas verdes son fotosintéticos y proveen gran parte de los requisitos de energía de la anémona.

"Aunque el color verde presente en algunos de estos animales es producidos por los mismos, este proceso solo puede operar cuando la alga simbiótica unicelular reside en sus tejidos." (Marine Life of the Pacific Northwest)

Los líquenes no son los únicos que viven unidos con algas.

Foto #3: Una anémona con tentáculos de un color más vívido. La columna está siempre cubierta de estos tubérculos verdes.

Mientras desaparece el agua, las anémonas empiezan a cerrarse.

Foto #4: Mitad en agua,  mitad en seco. 

Foto #5: Y cuando el agua se ha ido completamente, las anémonas más bien parecen donas rellenas de jalea de fresa.

Estas anémonas crecen en la roca. La arena se acumula alrededor. Cuando esta arena ya se secó, las anémonas se habrán encogido aún más, dejando apenas una leve depresión en la superficie de la arena.

Hasta que suba la marea de nuevo.

Gotcha!

Walking among the tidepools, I see trembling in the water a few metres ahead; small critters, fish and crabs sensing my presence and racing for cover. By the time I reach the pool, it's apparently empty. Seaweeds stand unmoving, a few shells lie abandoned here and there (when I pick them up and wait a while, they sprout legs; they weren't so abandoned after all.) There are no crabs, no fish.

No matter how long I wait, standing beside a tidepool, the fish don't show up; they see my shadow.

My camera usually wears the 40mm lens, good for getting within an inch of a tiny critter, or the old kit lens, which zooms, but is not good at detail. This time, I used the 85mm lens; it does not zoom, does not permit me to take photos at distances less than a metre or so, (so no rock-flipping - snap photo before everything scrambles for cover photos) and has a shallow depth of field. But it does let me take a fairly decent shot of a small critter from a distance.

So I sat a couple of metres away from a few tidepools until the residents decided I must have gone home or turned into a rock, and ventured out again. Still too close; moving to aim the camera was enough to send everyone back into hiding. But I got one photo of a tiny fish.

Baleful glare: In about an inch of water. The fish is an inch or so long. There is also a baby hermit crab near the edge of the photo.

Two grainy hand hermits, cautiously emerging from the shells. I moved too close, and they hid again.

I see many of these shells empty on the beach. I brought some home, but my hermits refused to use them. They like shells with a rounder opening. Now I think I know why; most of my hermits are Hairies, Pagurus hirsutiusculus, and these two are Grainy Hands, P. granosimanus. I'll bring home a few of the larger ones (my grainies are big guys) and see if they get used.

On the underside of a stone. Lay the stone down, step back a metre, aim; everything fast is gone. the big Wosnesenski's isopods are leaving as fast as they can go. Only the little stubby isopods have stayed put, pretending to be pebbles.

I see these sea slaters (aka beach cockroach) often just above the tide line. They are very shy, extremely fast, and are hidden long before I'm in range. I got these from about three metres away.

Just rocks and the dropping tide.

Thoughts on a rocky shore

I love a rocky beach.

Polished rocks, a sprinkling of barnacles

The current runs strong along the eastern shore of the Georgia Strait, and the tides pound in and drain out quickly. Many of the rocky areas are like this; water-polished rocks, with very little life visible. Turning over stones at low tide, I find more smooth stones. No crabs, no hermits, no worms. They must be there, but have retreated to deeper, safer hideouts.

Sometimes there are barnacles, in flatter areas thickly covering the stones, in other spots clustered on the sheltered sides and bottoms of the rocks. There are spots where none are to be seen, where the rocks shine as if they were waxed and buffed.

Down near the lowest tide line, seaweeds cover the rocks. It's dangerous walking; the weeds are slippery, and the rocks move underfoot. No matter how carefully I step, I'm always a twisted ankle away from a spill. But here, the crabs and other critters find a refuge. From the waves, from hungry gulls, and also from me, as I usually gingerly skirt the greenest areas, keeping an eye on the water's edge, ready to hurry towards land when the tide turns; I don't want to be caught in seaweed over stones as the water races in. Too risky.

A flatter spot, in the lower intertidal zone, with small erratics and tide pools. More barnacles here.

Coming towards a tide pool, I see ripples and splashes at the surface. By the time I get there (and sometimes I sneak up from the far side of the rock) there is nothing. The pool looks empty, just more clean stones with clear water. Even the tiny fish have hidden underneath the stones.

But there are always snails. Tiny, and tinier snails, dotting the rocks, basking in the warmth or resting in a tide pool. Most are pinhead size, some as "big" as a grain of rice. They hold on tight, or don't provide enough resistance to the waves to be washed away. Maybe their shape helps; smooth and rounded, with a sharp tip.

Under an inch of water in a tide pool, rice-grain snails and a few limpets choose the warmest rock.

Everywhere else, where I find tiny snails, a good half of the shells house miniature hermit crabs. Not here. I think I saw one leg poking out of a shell; otherwise, every snail shell is full of snail. Hermits can easily be bowled over by a wave and swept away.

The tiniest snails are a worry for me. In some spots, every decent-sized stone is covered with them, like sprinkles on a donut. I can't put my foot down without stepping on some. I try to brush them aside, but risk tripping myself up as the stone shifts. I am glad my shoes have deep ridging; at least some of my footprint is safe for tiny critters.

Sand is safer, for the snails, and for me.