Showing posts with label Sargassum muticum. Show all posts
Showing posts with label Sargassum muticum. Show all posts

Thursday, May 08, 2025

On the shady side of wet rocks.

So many different beaches; sandy, rocky, seaweedy, stony, steep, slippery, lumpy ... For this low tide day, I chose a smooth, flat, sandy one, for ease of walking. An unfortunate choice. The tide didn't go out far enough to reach the eelgrass beds, where little scuttling and sliding critters would find shelter. The sand reached to the edge of the water, and everything except sand dollars were already sheltering deep in the sand. And the sand dollars were hurrying, as fast as a sand dollar can hurry, to bury themselves.

But there were rocks. Good-sized rocks, mostly standing well apart; glacier droppings. Around each, the current has dug a shallow depression, and on the shaded side, it's business as usual, even at low tide. I went from rock to rock, checking out those tidepools.

From a few metres away, I could see movement; quick, darting dashes for cover; small fish startled perhaps by the vibration I was making in the sand, perhaps by my shadow. Crabs, maybe, heading for the deepest crevice under the rock. When I got to the edge of each pool, nothing was moving. I waited, sometimes, pretending to be another rock. The fish were more patient than I.

Seaweed doesn't hide. And anemones keep fishing as long as there's water.

Algae, red, green, brown. Turkish towel, sea lettuce, and Sargassum.

Burrowing anemones, green and palest pink. And one slow crab.

A salad bowl; Moon snail egg collar, with shredded sea lettuce and red, twiggy algae.

Two plumose anemones hanging from the rock. The water still covers their mouth, so they keep those tentacles spread open.

It's good to see healthy purple starfish again. More sea lettuce, red, bladed algae, and another green anemone.

A silvery plumose anemone, almost entirely out of water, tentacles retracted. Sea lettuce, and small, orange thingies; sponges?

Next: on/under the sand.

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

Tantas playas, de tantos tipos distintos: arena, rocas, piedritas, algas marinas; resbalosas, firmes, inclinadas ... Para este dia de marea baja, escojí una playa arenosa, plana y firme, donde sería fácil de caminar. Una decisión desasertada. La marea no bajó suficientemente como para que alcanzara las areas donde crece la hierba Zostera, donde las criaturas activas pueden encontrar abrigo. Hasta la orilla, se extendió la arena, y todos los residentes, aparte de los dólares de arena, ya se habían escondido de la luz y el aire. Y esos dólares de arena se apuraban, tan rapidamente como un dólar de arena puede apurarse, para desaparecer también.

Pero hubo piedras. Piedras de buen tamaño, bien separadas; desechos de los glaciares. Alrededor, las corrientes han formado depresiones en la arena, y en la sombra, la vida sigue, aun a marea baja. Caminé de una a otra de estas rocas, examinando esas pozas de marea.

Desde una distancia de unos pocos metros, podía ver movimientos rápidos; pececitos tal vez asustados por la vibración de mis pasos, tal vez por mi sombra. O cangrejos, quizás, buscando la grieta más oscura bajo la roca. Cuando llegaba a la orilla de la poza, nada se movía. Esperé algunas veces, imitando la roca. Los peces demonstraban más paciencia que la que tenía yo.

Las algas marinas no se esconden. Y las anémonas siguen buscando alimento mientras haya agua.

  1. Algas marinas roja, verde, marrón. Toalla turquesa, lechuga de mar (Ulva sp.), Sargassum multicum.
  2. Anémonas Anthopleura artemisia, verdes y color de rosa pálida. Y un cangrejo sin apuros.
  3. Ensalada mixta. Un collar de arena, que es una masa de huevos producido por el caracol luna. Con algas verdes (lechuga de mar, Ulva sp.) y ramitas de un alga roja.
  4. Dos anémonas plumosas (Metridium senile) colgadas de una roca. Como el agua todavía les llega a la boca, siguen con los tentáculos abiertos.
  5. ¡Que bueno es ver las estrellas de mar sanas ahora! Ulva sp., un alga roja, y otra anémona verde.
  6. Otra anémona plumosa, esta con los tentáculos retraídos, ya que está fuera del agua. Las cosas anaranjadas pueden ser esponjas.
Para mañana: criaturas en la arena.

Tuesday, May 06, 2025

Kelp crab, with matching seaweed

I caught a low, low tide a week ago. I've been processing the photos ever since. Just about done. Meanwhile, here's a kelp crab. And seaweed to match.

The kelp crab, Pugettia producta, on his way to hide in the Sargassum. It's an invasive species, but the kelp crab finds it useful. The little brown balls are the seaweed's floats.

Tomorrow: tide pools.

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

Hace una semana llegué a tiempo a la playa para pasar unas horas a lo más bajo de la zona intramareal. Desde entonces, he estado procesando fotos, ya casi termino. Mientras, aquí está un cangrejo kelp, y un alga marina que le va a servir de camuflage.

Foto: Pugettia producta, apurándose para esconderse bajo las algas Sargassum muticum. Esta es una especie invasiva, pero a estos cangrejos, les resultan útiles. Las pelotitas son vesículas llenas de gas que sirven como flotadores.

Mañana, pozas de marea.

Friday, April 14, 2017

10 cm a day

I've been looking again at the wireweed in my aquarium. Branches break off and float to the surface; I remove them, a branch or two daily. And yet the amount of wireweed never seems to diminish.

Wireweed (Sargassum muticum), in the "empty" end of the tank.

Sargassum muticum is usually 1-3 m in length, but can grow up to an incredible 16 m in length in certain habitats, and can form floating mats on the sea surface. It can grow at up to 10 cm each day, and it also has a relatively long life-span of 3-4 years. ... Dense mats of Sargassum can form very quickly. (The Seaweed Site)

The branch I removed this evening was 12 cm. long. I'm beginning to see why the total amount in the tank remains the same.

Section of today's crop, showing bladders, reproductive structures, and a few leaf fragments.

Sargassum muticum is an invasive seaweed, originally from Japan. It has spread enthusiastically to the west coasts of both Europe and North America; on this coast, its range goes from Mexico to Alaska. Besides its fast growth habit, it is also extremely good at starting new plants.

Branch tips with reproductive vesicles. They look like miniature cucumbers. The bumps show that they're mature and ready to spread "germlings".

A branch doesn't have to be attached to the parent to reproduce itself. It can float free for months, still growing, still fattening up these "cucumbers". The infant plants ...

... develop into small germlings and develop adhesive rhizoids (rootlike structures), at which point the offspring will release from the parent plant and sink to the bottom; where they will adhere to whatever substrate they land on. (Sargassum muticum)

I've been noticing a lot of new, brown growth on the glass of the aquarium. I wipe it off every couple of days; I've never had to do that before. Are those new baby wireweed plants?

Broken branches float to the surface. They are buoyed up by dozens of small bladders full of air. In the wild, they float away from the parent plant, seeding new territory as they go.

Gas bladder. Leaves and reproductive vesicles in the background.

Another gas bladder. These get up to about 3 mm across.

Nicholson et al. (1981) reported on a possible short-distance dispersal mechanism they called "walking Sargassum," in which entire plants attached to fist-sized rocks drift with the currents and sink to the bottom where the water slows. (Exotics Guide)

Wireweed has created problems where it has taken over territory, cutting off light to eelgrass and other plants, fouling shores, pushing out native species. Attempts at removing it, (up to 480 tons in three years in southern England: it was back again the next year) have been unsuccessful. In my tank, I can rip it out, scrub the walls, replace the stones, and maybe get rid of it. Maybe.

But I've noticed, with other invasive species, like the Asian mud snails, how after a few years, the natives begin to fight back, and eventually come to a new balance. Nature does love variety and resists monoculture. It will be interesting to watch how it works out in our waters.

And my hermits are beginning to find it interesting; at any time, day or night, three or four are clambering through the upper levels. They do love a climb!

(On the branch above, the longest leaf I found was 6 mm. long, the bladders were up to 3mm., and the "cucumbers" are up to 4mm. long, about 1mm wide.)

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