Anemone doings

Intertidal plumose anemones stand tall underwater, waving their tentacles (up to 100) about, catching small prey. When the tide goes out, they droop, hang straight down, following the water as it recedes. As long as the water reaches the mouth, the tentacles stay extended; there's good food to be caught in the ebb and flow.

When the water is gone, the anemones retract their tentacles and contract their bodies, squeezing out the water that bulks them up. Eventually, they end up hanging limply, looking like slimy old rags. They're fine; when the tide comes up again, they'll inflate, spread out the tentacles and get down to the business of fishing.

I caught this group in that half-way stage, some still with their mouths in the water, some closing up shop.

Plumose anemones, Metridium senile.

Four anemones. Two have their tentacles still in the water. The one on the left is on the point of closing  down; the one on the right is still busy feeding. As it has turned downwards, now its tentacles brush the sand; see what effect that has, in the next photo. Note, also, the stretched stem; taking on its old rags look.

Angry anemone

A lot is happening in this photo. Three anemones still feeding. Two shrinking, with tentacles retracted. Look at the one on the right; it's dripping, and it has shed inedible grains of sand that stuck to it as it hung down, now resting on the tentacles of the one still open.

The one in the centre is unhappy. These anemones, when disturbed or threatened, shoot out fine white threads through the column wall. These threads, called acontia, contain stinging cells. They may be discharged as protection against predators, such as nudibranchs.

These thread-like extensions ... are filled with nematocyst-containing cnidocytes ... the dart-like tubules are propelled from the nematocysts with enough force to penetrate the exoskeleton of the predator to sting its target with ... toxins that cause paralysis. (PubMedCenter)

Or they can  be a territorial marker. These anemones are clonal; they live in groups of their own clones. When they find themselves too close to another of the same species, but of a different clone group, they expel the acontia. "Stay away!"

And they don't like the aggregating anemone, Anthopleura elegantissima. When they contact one, there go the acontia. It is possible that the one above has met one of these down there under the rock. Or could there be a nudibranch hiding in the dark?

Ten years ago, I had to move a plumose anemone in my tank, and she was extremely annoyed. Here she is, shooting acontia at me.

"Metty"

Story here.

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Las anémonas intermareales se mantienen erguidas en el agua, agitandos sus tentáculos (que pueden llegar a 100) capturando su presa. Cuando la marea baja, se  desinflan, se doblan, colgándose con lost tentáculos vueltos hacia abajo, manteniendo la boca en el agua. Siguen pescando; en el agua en movimiento siempre hay comida buena.

Cuando por fin no encuentran agua, retraen los tentáculos y se contraen, expulsando el agua que les da forma. Terminan colgándose flácidamente; parecen trapos viejos. Pero están bien. Cuando sube la marea, se volverán a inflar, volverán a extender los tentáculos y dedicarse de nuevo a la pesca.

Encontré este grupo de anémonas en medias res.

    1. Anémonas plumosas, Metridium senile.

Aquí hay cuatro anémonas. Dos todavía tienen agua para sus tentáculos. La de la izquierda está a punto de retraerlos; la de la derecha sigue alimentándose. Por estar ahora boca abajo, sus tentáculos están en contacto con la arena; en la próxima foto se ve lo que esto ocasiona. La columna ya se está extendiendo, ya empieza a tomar la forma de trapo viejo.

    2. Una anémona enojada.

Mucha actividad se ve aquí. Tres anémonas están pescando. Dos se están encogiendo, con los tentáculos retraídos. La de la derecha gotea, y  ha dejado caer granitos de arena que se le pegaron al extenderse hacia el fondo.

La anémona del centro está de malas. Estas anémonas, al estar amenazadas o simplemente irritadas, expulsan hilos blancos por la pared de la columna. Estos hilos, llamados acontia, están armados con células urticantes. Pueden servir como protección contra los predadores, tales como los nudibranquios.

Estos tejidos filiformes ... están llenos de cnidocitos que contienen nematocistos ... los túbulos en forma de flechas se disparan desde los nematocistos con sufficiente fuerza para penetrar el exoesqueleto del predador e inyectarlo con ... toxinas que causan una parálisis. (PubMedCenter)

O pueden servir como marcador de territorio. Estas anémonas son clónicas; viven en grupos de sus propios clones. Cuando se encuentran cerca de otra, de la misma especie, pero de un clon distinto, producen las acontias. "¡Lárguense!"

Yno les gustan las anémonas agregadas, Anthopleura elegantissima. Cuando se ponen en contacto con una, orta vez expulsan las acontias. Es posible que la anémona de la foto haya encontrado una de estas otras anémonas debajo de la roca. O puede haber un nudibranquio escondido allí.

Hace diez años, tuve que cambiar de sitio una anémona plumosa en mi acuario, y ella se puso muy enojada. Aquí está amenazándome con muchas acontias.

    3. Se llama "Metty".

La historia está aquí.

Disaster averted

I don't post very many photos of my aquarium critters these days. It's not a lack of interesting things going on, but most of them don't show up in photos. And have been discouraging, as well.

I've been collecting fresh seawater for the tank every couple of weeks. Until this spring, the best access point (with my heavy 5-gallon buckets) was at a local boat launch, where I had a platform to stand on over water deep enough. Then the city decided to "improve" it. First, it was blocked off with fences, then the heavy machinery came in and played in the mud all summer. I found another access point, a few miles down the road, which worked fine until the winter storms blocked it with logs, and a sign went up, saying that the logs would remain until spring.

Okay. I went back to the old boat launch, that was now open. Very nice: two long piers out into the water, anchored with a post at each end, a clean cement ramp leading down, as opposed to the slippery, uneven slope I stumbled over last year. Very nice. I filled my buckets easily and took them home.

And almost killed my whole tank. As soon as I changed the water, all the anemones shut down immediately. The big brown plumose anemones started sending out her distress symbols: acontia - long white threads streaming out from her body. The crabs and hermits sat still, looking sleepy; they were not interested in food.

"Metty" in a bad mood. Photo from 2015.

But everything looked good! The tank had been scrubbed, the water was clear, the pump and bubbler were going strong. I gave them a few hours to recover, and looked again. Worse. Some of the anemones on the walls had just given up and were mere smears on the glass. "Metty" was an angry brown disk. The crabs were barely moving.

I checked the water. The salinity was 'way down, the acid level 'way up. I corrected these with salt and bicarbonate, added water conditioner. That should have fixed it.

But where did the salt go, and where did the acid come from? The nice, fresh, clean, but still uncured, cement works at the boat launch, maybe? And did the "improvements" include re-routing a stream into the launch site? With fresh water, and possibly lawn and business run-off? What other poisons came along with that cool, clear water?

When, two days later, none of the anemones seemed to be recovering, and no-one had any appetite, I went for water again. This time, to a beach where I had to wade into the surf, then haul my buckets over logs and rocks and slippery sand and a lawn to reach the car. (A man passing by saw my struggles and came to help; much appreciated!)

I changed the water again. The crabs woke up. The hermits discovered their appetites. And slowly, so slowly, the anemones took in water, opened cautious mouths, waved tentative tentacles. My largest pink-tipped green anemone - so beautiful she had been! - had broken down into three or four brownish chunks and fallen to the bottom of the tank. Two of the chunks now anchored themselves to shells and looked about for food.

Today, a month later, they're still cautious. But the pink-tipped anemone is finally pink-tipped again. And the crabs and hermits are enthusiastically pairing up; I have two pregnant crabs.

And spring is coming. And the logs will be gone. And - I hope - no-one will try to "improve" the second boat launch.

"Hi, there!" Waving female crab. She may be newly in berry.

A very annoyed anemone

When it takes all day to walk six inches, location becomes very important; you can't just up and leave if something's not right. This is maybe why plumose anemones congregate on the bottom of floating docks; the water is always at the same depth, the light is never too bright, there's always a current, as the tide rises and falls. No worries.

My plumose anemone made the mistake of parking on a clamshell on the sand near the low tide mark. And therefore, she* got harvested, and came to live in my tank. Where I try to keep her happy. I keep the water clean and cold, the pump and the bubbler running, the salinity level constant. I feed her shrimp pellets, which she seems to like.

Short plumose anemone, Metridium senile, as she was when she moved in.

She abandoned her clamshell soon after she arrived, and wandered around until she found a sheltered spot under the lip of an abalone shell. She's been there ever since. But shells gradually dissolve in salt water, and this one has been in the tank for some years; it's getting thin. The curved lip has crumbled away until there is a hole in the "roof" big enough for a large hermit to crawl through. It was no good as shelter any more. Last week, "Metty" decided to move.

She walked down and out of the shell, up the wall, and around until she found a nice, dark spot with lots of good current. Right at the top of the wall, under the pump. Not a good choice.

She didn't know that the pump gets removed every week, for cleaning; that the water disappears, that the wall gets scrubbed. So she would have to be encouraged to find a better home.

Anemones have stinging tentacles, which they use to trap their food. But when they are disturbed, they pull them inside and close down. Apparently, they are left with no defenses. Just apparently. An upset anemone instantly expels long, stinging strands, called acontia, from pores all around the body, and from the mouth.

Metty, shut down, and fighting back.

I was advised to use a metal knife to push at the foot of the anemone to make her want to move. It worked fine with Val, the burrowing anemone, when I moved her to a new tank, but "Metty" wasn't happy about it. She held on so tightly that I had to push the knife all the way under her, damaging her foot. And then, when, the ultimate indignity, I took her entirely out of the water to transfer her to a new shell, she started spewing out these long acontia.

NOTE apparently, holding the anemone upside-down out of water causes it to extrude its acontia, which then hang down by gravity and can be measured. (From A Snail's Odyssey)

I didn't measure them, but they were noticeably longer than the tentacles. They may be as much as 4 inches long, about the length of a mature anemone. And they're more potent than the tentacles, too; the nematocysts are larger, contain more toxins, longer spears.

The filaments are endowed with highly potent nematocysts, are ciliated, and can crawl about on the anemone’s surface. (ASO) 

I moved her, still angrily shooting out more acontia, to a bowl in a dark corner while I cleaned the tank. And then, an hour later, I transferred her, shell and all, back to the clean tank.

Still sulking, but the acontia are gone, and she's starting to open her mouth.

5 minutes later, she's decided to forgive me. Memories are short, and the pump is running.

By morning, she'd glued herself to the oyster shell, and was standing tall. I fed her two shrimp pellets tonight, and she accepted them quickly. Life is back to normal.

"Feed me!"

Hiding behind the seaweeds. She's a little over 3 inches tall here, taller than she was six months ago.

I don't think she'll stay on the oyster shell long. I hope she finds a better home than the last place. Because I don't really want to move her against her will again.

*Why I call her "she": these anemones are protandric hermaphrodites, meaning that they start out as males, then become females in adulthood. I assume "Metty" is an adult, so she's probably female already.