Leafy hornmouth and friends

Each critter that arrives in my aquarium, whether I brought it in on purpose, or it hitchhiked on seaweed or on a barnacle rock, or even if it was born in the tank, brings with it a responsibility. They each have their own specific diet to be provided, their own habitat needs; hiding spaces, climbing structures, sand or rocks, water currents and temperatures, company of their own sort. And providing those needs brings in more critters: the predators need prey, the gregarious ones need friends.

I don't know how the leafy hornmouth snail came to the tank. Maybe he arrived in a clump of mussels, brought in to feed the whelks. Or in a handful of seaweed. But he's here, and growing, (6.5 cm long now) and hungry. He eats barnacles and mussels, which means that I have to go shopping for barnacled rocks.

In between meals, he wanders around the glass walls.

Leafy hornmouth snail, Ceratostoma foliatum

Limpets travel on his back, and a family of orange-striped green anemones take advantage of the ever-changing currents; there's good eating in that water!

Foot and passengers

Spring is here. I guess I should be looking for a mate for him (or is it her? They know; I can't tell.)

One of the limpets. The yellowish blobs are limpet poop.

Empty snail shell with another orange-striped green anemone.

Next: leaving the tank behind and heading out into the forests again.

~~~~~~~~~~~

Cada animal que llega a mi acuario, sea como sea que llegue, trae una responsabilidad. Cada uno tiene su dieta preferida, sus requistos para el habitat: necesitan lugares para esconderse, estructuras donde pueden trepar, arena o piedras, corrientes de agua rápidos o suaves, temperaturas específicas. Los animales de rapiña necesitan su presa natural; las criaturas gregarias necesitan compañeros.

Y al traer lo que piden los habitantes del tanque, vienen otros animales, con sus propias necesidades.

No sé como llegó el caracol "leafy hornmouth" al tanque. Tal vez se escondió entre un grupo de bálanos; tal vez vino en una bolsa de algas de mar, traídas para comida de los cangrejos y ermitaños. Pero aquí está, creciendo rápidamente; ya mide 6.5 centímetros de largo. Y tiene hambre.

Come bálanos, mejillones y almejas, lo que me obliga a traer piedras cubiertas de bálanos y de mejillones de la playa para mantenerlo sano.

Cuando termina de comer, anda dando vueltas en las paredes.

Las fotos: el caracol, con las anémonas que se aprovechan de una base móvil; así les toca mejor comida. Una lapa. Otras están pegadas a la parte trasera del caracol; este está comiendo algas en el vidrio. Las bolitas amarillentas son caca de lapa.

Y finalmente, una concha vacía con otra anémona (anémona verde con rayas anaranjadas: Diadumene lineata.)

(Y ya es primavera; quiere decir que el caracol estaría más contento (contenta? Yo no sé distinguir, pero ellos sí saben.) si le traigo una compañera. Otra visita a la playa cuando la marea está baja.)

Mañana; dejo el tanque y me voy otra vez al bosque.

Waste not ...

It's not only the hermit crabs who use leftover empty shells:

Orange-striped green anemones, Diadumene lineata, in empty barnacle shells.

These tiny anemones are quite mobile, and flit from wall to rock to shell to seaweed, always seeming to search for variety. Or maybe safety; these ones are staying put. No-one steps on them, no-one tries to push them aside.

Room with a view.

Anemones doing what anemones do.

(This one's for Lucy.)

Living with sea creatures especially invertebrates, there's a routine: chill, feed, clean, chill, change water, clean, feed, chill, change filters, chill ... After a few years, it becomes almost mindless, a chore like washing the dishes or sweeping the floor. It could lead to boredom.

Except: day after day, as I watch, there's always something new to learn. Even apparently passive beasties, like anemones, have their likes and dislikes; they get grumpy if things are not just right; they wave enthusiastic approval when life is good.

Pink-tipped green anemones, two days ago. Today, the one on the left is twice as long; she's splitting into two.

The small colony of these pink anemones has been multiplying since I started hand feeding them, rather than letting the water bring them goodies. Out in the ocean, they congregate in the cracks at the base of rocks, where detritus brought in by the tide gets trapped. In my tank, since it gets cleaned out regularly, there are no wonderful treasure troves, and the current sweeps good food right past their open mouths, too fast to be grabbed; they survived here, but they didn't grow or multiply. Now they do. And their colours are brighter. They're happy!

They like the hermit crabs' shrimp pellets, so I have to feed them twice or three times each day; once or twice, and the hermits steal the pellets out of their mouths, even though they (the hermits) have already been fed. (They're greedy little things, and someone else's food is always preferable to what they already have in hand.) By the third mouthful, the anemones are usually allowed to swallow.

If you look closely at the space in between them, on the old oyster shell, there's a spot with a back-and-forth pattern; snail or maybe limpet scrapings.

The oyster shell is ridged or layered, as in the area at the top; this bottom pattern is new.

The big burrowing anemone has her own quirks.

My burrowing anemone, fishing for plankton. She also likes shrimp pellets, and waves her tentacles enthusiastically for two days after a good feed. Then she hunkers down and sulks until I change and chill the water again.

Bits of shell, grains of sand, and random "stuff" stick to the anemone's column. Small hermit crabs, assorted snails, and courting amphipods like to hide around the base, but never seem to get stuck. Or stung. (Crabs do get stung. She's not a friend to crabs.) I've never seen a limpet touch her.

The greenish yellow spots are algae growing on the glass, not on the anemone itself. No matter how often I scrape them off, they're always there.

Brave little crab

A crab in the aquarium tries to steal food from the anemone. Trouble is, the anemone fights back.

The anemone tolerates hermit crabs crawling all over her, stealing food, scratching at her sides, just resting. But crabs are not allowed. Her stinging cells (nematocysts) react to the touch of a crab and attempt to trap or poison the invader.

Each nematocyst contains a small venom vesicle filled with actinotoxins, an inner filament, and an external sensory hair. A touch to the hair mechanically triggers a cell explosion, which launches a harpoon-like structure that attaches to the organism that triggered it, and injects a dose of venom in the flesh of the aggressor or prey. This gives the anemone its characteristic sticky feeling. (Wikipedia)

When the crab is large, it is seen as an agressor. A small crab is prey; if caught it is quickly swallowed. The next day, the anemone spits out a clean crab carapace.

Thoughts while cleaning the aquarium

Some time ago, I read a conversation with Dr. Marian Dawkins, where she was asking, "What do animals want?" She makes the point that animals need more than food and shelter; they have feelings about things; they have their own likes and dislikes. Not human likes, but theirs, their own particular quirks.

A few quotes from the conversation:

But also most people think that there's something more to animal welfare than just not dying of a disease. That more is, in my view, what the animals, themselves, want. Do they want access to water; do they want access to cover? Do they want to be with each other? Obviously we can't necessarily give them everything they want. But we can at least find out what it is.

I became interested in the idea that not only could you ask animals what they wanted, to give them a choice, but you could actually ask them how much they wanted something. 

My argument is saying, because we don't understand animal consciousness, we ought to be opening our eyes to the possibility that a great range of animals, not just mammals, not just birds, maybe invertebrates are conscious as well. It seems to me that by saying we don't understand consciousness, you're not closing off animals' consciousness. You're not denying animal consciousness altogether. You're just simply saying we don't know and therefore it might exist in a much wider range of animals.

I was surprised that she mentions invertebrates, although most of her work is with farm animals and pets. It made me look more closely at my tank full of critters, all invertebrates. What do they want? What are they thinking?

Happy hermit?

My cat comes in, wet and cold, and climbs on my lap. I pet her, scratch her ears and neck; she purrs and purrs. I stop scratching and she nudges my hand; "Come on, don't stop now!" She lets me know what she wants. She tells me when she's happy. She lets me know when she's annoyed with me. (And her claws are sharp!)

My neighbour's dog sees me and runs to drop her ball at my feet, then looks at me expectantly. I know what she wants, too. It's not just food and shelter. It's fun. It's companionship. It's someone telling her she's a good girl.

Cleaning the tank, I remove all the animals, each species to their own bowl or basin. I give the hermits and crabs pieces of dried shrimp; they love these. When the tank is clean and refurbished, I move the hermits back, one by one. Each one comes holding his little morsel of shrimp, tightly. Rarely do they drop it on the way over.

If they were kittens, would they be purring?

Orange striped green anemone. Likes shrimp, too. Likes to wander about. Doesn't like hermits.

Miniature worm, fishing for goodies. If he were a dog, would he be thumping those tentacles on the floor?

Baby shore crab, just standing by the glass, watching me over her shoulders.

The crabs like shrimp, but when they're travelling, they don't want any. They walk around and around, trying to find the way home. I move them back, and they start digging. Forget treats! They've got work to do!

Crabs love to dig, but it doesn't seem to have a purpose. When they've finished a burrow, they move out and start to dig somewhere else. Is their digging more akin to my stumbles down a rocky shore, not going anywhere, just there for the pleasure of the sun on my back, the fresh breeze in my face, the good ache in my legs when I'm back home in my favourite chair?

Do shore crabs smile as they dig?

Lined chiton. What does he like? I don't know. Yet.

Pair of amphipods, courting. She's the orange one; he will hold onto her for days.

The amphipods and limpets, the snails and chitons and anemones, don't know I'm here. The crabs do; they come to the glass and wave pincers at me, challenging me, maybe. And the hermits are as curious as a jumping spider. Or a kitten. They watch me. They grab at my fingers, or the chopstick that I sometimes use to move the seaweeds aside. They pick at it, taste it, try to climb it. Curiosity; the desire to know something.

Long ago, I watched a hermit trying to climb a thermometer, just to see what was at the top. She kept falling off, but persisted until I gave her a "ladder". Once she'd reached the top and looked around, she slid back down and walked away, curiosity sated.

I'm curious, too: what do my critters know? What are they feeling? Do they know happiness? Loneliness? Grief?

Just wondering.

Butter fingers

At feeding time in the aquarium, as the hermit crabs race about, grabbing goodies, squabbling over them, mugging their erstwhile friends for a tidbit, trying to hog two or three meals (that's what all those extra mouthparts and pincers are for, aren't they?), the shrimp drifts down, casually, as if moved only by the currents in the water. As if he had no real interest in the proceedings. But let him drift within reach of a food pellet, and suddenly he's galvanized; faster than my eye can follow, he has bounced up to a handy perch, carrying his catch.

Three feet for perching, five for holding onto the food.

But he's not as efficient as the hermits and the crabs; even using several feet to hold on to the food, it slips out of his grasp and falls to the sand below.

And down he goes after it, breaking out all those extra swim fins to get there before the hermits do.

And the food pellet is snagged by a speedy crab. The shrimp drifts away; no big deal, not interested, really, not at all, he's not hungry, anyhow.

Rinse and repeat. It usually takes him three or four tries to collect a meal and get it into a safe place.

Intrepid explorer

Limpets are slow. They sit in one spot for hours, then slide gently away to find a bit of algae to munch on. Their food sits and waits for them; they have no need to hurry.

But  occasionally, one gets the urge to explore. I watched one rushing around and around on a hermit's shell.

Front end lifted, antennae flapping; no time to waste!

Taking a good look around. Wondering whether to move to the next shell. Nah.

Pair of observers on the wall: "Where's the fire? These youngsters nowadays!"

Blurry photo, but shows the foot-waving, shell-lifting urgency of Limpy's quest.

He stayed with the hermit for several hours, working his way from the tip of the shell to the lip, checking out the surroundings as the hermit wandered about, dashing (slow-mo dash) back to the tip, then the far side, then back to look over at the hermit's head ...

In the morning, he had moved on. The hermit's shell was clean and bare.

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.

Dancing anemone

I've been asked for photos of my entire setup. I'm working on it, but it's easier said than done. This is part of the reason why. I get sidetracked.

The big brown anemone that came home on Canada Day stands front and centre, more or less. Usually less; he's sulking. If the water's too cold, or too warm, or too old, or too slow, he sulks. If a hermit steps on him, he sulks. Sometimes, for no reason that I can see, he puckers up his mouth like a baby tasting a pickle, hunkers down, and sulks for hours.

And in between those times, he sometimes dances.

Lift those skirts!

Siamese anemones?

For a few minutes, I thought he was going to split in two, but no, he slid entirely off the shell he came home on, flapped his skirts a few more times, then slid back onto the shell and stood there sedately. He's there now, tall and glorious.

I'll post the whole kit and kaboodle tomorrow, I think.

All the little mouths

They bite.

Close view of a starfish's busy coat.

Solid white spines, translucent gills, and the biting pedicellariae; all those little open jaws.

I've been spending time sitting in front of the tank, chasing an annoying white crab, and noticed interactions between the mottled star and the other residents. The starfish wanders about slowly, minding his own business (finding something more to eat), ignoring anything not edible. He can afford to be complacent; he's wearing his own security guard.

A hermit crab passes him, and touches - just barely - an arm of the star, and immediately yanks away his pincer and backs off. The little annoying crab swats at anything that comes near him, like a kitten does. Unless it's the starfish. He raises a pincer to hit it, remembers, changes his mind, and goes to hide under a shell.

I watched as a few grains of sand fell onto the back of the starfish. They immediately started to move up over the arm, and off the other side.

The pedicellariae are at work.

More on the crab, later. I'm trying to get a photo of the shape of his carapace, but I'm sure he recognizes the camera already; he runs away as soon as he sees it.

 

Bullies!

"All bark and no bite," I said, about the black-clawed crabs in my tank, because they'll threaten me with amputation, but then sit meekly in my hand, all threats forgotten.

I was wrong. They're bullies, only attacking smaller and weaker neighbours. Not only snails, proper crab food, but other crabs, hermits, and, I think, bubble shells and polychaetes.

Ready for action.

The aquarium has been a good place for them; in five months, the big male has  grown from under 1/4 inch across the carapace to somewhat over an inch, with extended pincers twice that again. I've provided them with clean, cold water, gourmet crab dinners, a handy rock pile to live under; there was no need to beat up on the other residents.

But. Their neighbours included two shore crabs, male and female, grown up in the tank. The female, a large adult, disappeared. I didn't even find her remains. A few weeks later, the smaller male was gone, too.

I kept finding maimed and dying hermits. And the bubble shells that had lived all winter in the tank couldn't be found. The nudibranch got eaten. Even a big polychaete worm, one of the ones that can grow up to a foot long, even in a small tank, just wasn't there any more. And now there were only two black-clawed crabs; the female had seemingly evaporated.

But everything seemed right; I checked temperatures, salinity, acidity, current, filtering; all normal. So a couple of weeks ago, I brought home another three shore crabs to liven up the tank with their antics.

Two days ago, the largest (still smaller than the large black-clawed crab) turned up with three legs and a pincer gone on one side. Who would do this to him? Only another crab, and suspicion centered on that big black-clawed male, sitting so peacefully under his stone. While I pondered this, a second shore crab lost two legs.

So tonight, I've hunted down and arrested both black-clawed crabs. They're in solitary confinement, for now; the first trip to the beach, they'll go with me. And won't come home.

Small black-clawed crab, 1/2 inch across the carapace.

Now that I've got them out where I can watch them, I see that the small crab is terrified of the large one, and keeps a good distance away. He probably has good reasons.

The two traumatized shore crabs got extra goodies, in a bowl away from competition, and seem to be recovering.