Decorator colours

The plumose anemone in my tank has a brown column and  beige tentacles, a common combination. Often, though, they are white on white; a white column, and whiter tentacles. I had never seen one with a green head before.

Plumose anemone, Metridium senile in the tidepool under the glacial erratic. With green tentacles.

I browsed images on Google; I found a few white "Mets" with pale green tentacles, always in photos taken during a dive. This one is in a few inches of water. And that was the colour as my eyes saw it; I used the flash, because the anemone was in shade, but those tentacles were a definite blue-green.

Another. This one has white tentacles, but the base is a pale blue.

This one matches the one in my tank. Some of the red blotches around it are tubeworm "flowers".

Another "normal" M. senile.

Deep under the rock, starfish wait out the dry spell. The flat, spread out anemone seems to be a burrowing anemone, with its mouth exposed. Must have just eaten something. Maybe one of those little fish?

More vivid colours. A deep pink tubeworm, still fishing while the water lasts. The pink-tipped green anemones below have shut down for now.

Even the hermit crabs are wearing party colours. I spotted this one with those bright blue pincers, like the one I brought home last week.

Three hermits, a dead kelp crab,and limpets. The deep red  critters at bottom right are not fish; they're shreds of seaweed.

Kelp crabs are usually a dull olive green, sometimes greenish brown. I don't know if this one was joining the explosion of colour in his lifetime, or if there's some sort of blue-green algae that took over his carapace and legs after he died.

This photo was taken aiming straight down into a foot-deep rounded hole. There are many of these near the bottom of the intertidal zone; circular holes, smooth-walled, looking like someone at some time removed a bowling ball from the rock. What causes this? I don't know.

I am always on the lookout for nice whelk shells for my hermits at home. Here, around this erratic, there are many whelks, all healthy and shiny, but no empty shells. And almost every hermit crab I saw was wearing a smashed and broken shell. What happened to the fresh shells?

I feel sorry for these hermits; the ones I brought home were quick to switch into intact shells; they do know the difference. I almost feel like collecting some decent shells from my tank and spreading them around this tide pool. Or would the tide immediately haul them off and slam them against the rocks until they were full of holes?

Questions, questions.

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.