Busy doings underwater

It has been raining off and on. The snow here in town is mostly washed away, except for the muddy piles alongside the roads. And the sun sets at 4:19 these days. Not that you'd notice; it has been hidden all day behind heavy clouds.

These are good days to stay home and watch the goings-on in my aquarium.

A green isopod, Idotea wosnesenskii, on eelgrass.

These isopods live on rockweed and kelp. Most of them, and certainly this one when I first saw him, are the colour of the kelp they live on, a muted yellow-green. I do try to keep some kelp or rockweed in the aquarium, but it never lasts long. What does thrive in the tank is the Pacific rose seaweed, and this isopod has been hanging out in its deep pink shelter. When he arrived, on a handful of rockweed, he was green, but with all the rose seaweed he's been eating, he's turned this dull wine colour.

Hairy hermit, Pagurus hirsutiusculus.

The colours on his shell are patches of various algae; the deep red, as far as I can tell, is the crust stage of a leaf alga, possibly Turkish towel.

Grainy hand hermit, Pagurus granosimanus.

The collection underfoot is made up (as is much of the sand on the shore) of the remains of critters who, in this case, have grown up, lived, and died in the aquarium. Several species of limpets, one alive. At least 4 species of snail, a periwinkle, an Asian mud snail, a small carnivorous snail, and the big one, in import, that the hermit is wearing, plus fragments of many others. A piece of the molted pincer of a biggish crab. There are several anemones, the orange-striped green anemone, of which all that can be seen are the whitish tentacles. The little tube at the far left, I think, is the proboscis of a carinate dovesnail.

The hermits and crabs are scavengers. I feed them a variety of foods; a prepared shrimp/algae pellet, bug larvae pellets, dried seaweeds, dried slices of kelp stipe, dried shrimp, fresh or frozen sea lettuce. They clean out any shells where the owner has died, as they do in the wild. They also tidy up anything else organic that ends up in the water, so today I experimented by giving them a tiny piece of chicken gristle. That was 6 hours ago. Every time I've looked since, (including a minute ago) there were 3 or 4 hermits busy taking it apart, sometimes fighting over it. And the last time I looked, a carnivorous dove snail.

They are so spoiled!

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Ha estado lloviendo, en ratos. Aquí en el pueblo, la lluvia ha derretido toda la nieve, aparte de las acumulaciones de nieve y lodo al borde de cada calle. Y el sol se pone a las 4 con 19 minutos. No es que lo hemos notado; ya todo era oscuro a causa de las nubes densas.

Estos son dias en que apetece quedarme en casa observando las actividades de las criaturas en mi acuario.

Foto: un isópodo de quelpos, Idotea wosnesenkii, trepándose en hierba marina, Zostera sp.

Estos isópodos viven en los quelpos o en Fucus spp., un alga parda. La mayoría, como éste, la primera vez que lo vi, toman el color del alga, un verde amarillento o pardo. Trato de tener siempre algo de esta algas en el tanque, pero no duran mucho. Lo que sí prospera es el alga roja, Rhodymenia pacifica, que tiene un color rosa fuerte, el isópodo ha estado viviendo y comiendo entre esta alga, de allí que ha tomado este color vino oscuro.

Fotos: dos ermitaños, el "peludo" y el de "manos granosas".

El suelo debajo de sus patas se compone, como también las playas donde nacieron los ermitaños, de los restos de criaturas que nacieron, vivieron, y murieron en el acuario. Hay conchas de 4 especies de caracoles marinos: los bígaros, una Batillaria attramentaria - el caracol de lodo asiático, un caracol carnívoro, y la concha grande que lleva el ermitaño, éste uno comprado, originario de quien sabe donde. Además hay muchos pedacitos de otros caracoles. Hay varias especies de lapas, una viva. Varias anémonas, las anémonas verdes de rayas anaranjadas, de lo que lo único que aquí se ven son los tentáculos. Y parte de la muda de un cangrejo. El tubito que se ve a la izquierda es el probóscide de un caracol Alia carinata.

Los cangrejos y los ermitaños son carroñeros. Les doy una variedad de alimentos: gránulos preparados conteniendo algas y camarón, gránulos de larva de insecto, algas secas, quelpo reseco hecho en casa, camarones secos, lechuga marina fresca o congelada. También, de costumbre, vacían y limpian las conchas de cualquier animalito que se haya muerto. En sus aguas natales, también se ocupan de cualquier material orgánico que llega a caer al agua. Así que hoy hice el experimento de regalarles con un pedacitito de cartílago de pollo. Eso hace más de seis horas. Desde entonces, cada que los voy a ver, hay tres o cuatro ermitaños ocupados en deshacerlo y hasta peleándose si uno parece estar comiendo de más. Hace un poco, también hubo un caracol carnívoro, el Alia carinata.

¡Tan consentidos son!

Hitchikers and their kin.

My little home aquarium is a self-sustaining habitat. (Well, with a lot of work on my part, but that's just maintenance, making up for the lack of the tides which keep their home clean on the shore.) It's always full of life. Because over the years critters keep appearing, sometimes coming in on seaweed brought in, groceries for the current residents, sometimes sandwiched between barnacles I bring home to keep the snails happy. And sometimes they just sort of appear, whether brought in as eggs or floating in the clean water I collected at the shore. I'm cleaning the tank, scraping off brown algae, getting rid of leftover crumbs, and I see a tiny shape, sometimes just a hint of movement, a crab-like walk, or a waving tentacle. Something new living in the tank.

And I have to keep up the maintenance because I can't abandon my tiny friends, not without carrying every single one down to the proper level of the intertidal zone and releasing it safely. 

Green isopods arrive clinging so tightly to rockweed that I don't see them, even while I'm rinsing it off before I anchor it in the tank.

Rockweed isopod, Idotea wosnesenskii. Showing up on a piece of red alga. About 4 cm. long.

A fourteen-legger. Notice the hooks at the tip of each leg. They cling tightly to the algae, so that even with strong wave action (or me harvesting it) they are not dislodged.

And growing up in the tank is a large community of tiny isopods.

Isopods on an oyster shell. The largest are about 5 mm long. 

A large one, captured on its own.

Whenever I take a shell out of the tank, I find it covered in these critters, all running about, always in a hurry. I don't know what species they are.

A mussel shell, holding two isopods, and a couple of amphipods (the curly ones). The isopods always lay flat.

And this: I first noticed it a month or so ago. It was stuck to the glass below the sand level, only the size of one of the isopods, and looked like a baby limpet from that point of view. But the shape was wrong; it looked oval, not circular. Even with a lens, that was all I could see, but I thought it might be a chiton.

Two weeks ago, it turned up, now recognizable, on an oyster shell. And today it was on a small rock, which I took out, still keeping it underwater, to get a photo.

Woody chiton, Mopalia lignosa. With two orange-striped green anemones.

As far as I can tell, he's a woody chiton. If so, he will grow up to 8 cm. long. Today, he 1.7 cm.

He was not pleased with the trip. As soon as I replaced him in the tank, he hurried back to the oyster shell. These are shy beasties, hiding on the underside of rocks and shells. There, he barely moves from one day to the next, just peacefully eating algae and diatoms; he especially likes green sea lettuce, Ulva spp.. Tomorrow is a low-tide day; if the weather holds, I'll go find a handful of the lettuce for "Woody". And some eel-grass for the hermits, kelp for the crabs, barnacles for the carnivore snails, and ...

And no telling what else will hitchhike in.

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Mi acuario casero es un habitat que se sostiene vivo solo. (Bueno, aparte de mucho trabajo de mi parte, pero eso es mantenimiento solamente, debido a la falta de la marea, que en el mar les mantiene su casa limpia.)  Siempre sigue llena de vida. Porque año tras año siguen apareciendo criaturas nuevas. A veces llegan escondidos entre las algas que traigo a casa para la comida de los residentes ya presentes; a veces se cuelan entre los bálanos que mantienen felices a los caracoles marinos. Y muchas veces aparecen como por magia, tal vez habiendo llegado como huevos o como el plancton que flota en el agua que traje desde el muelle.Estoy limpiando el tanque, raspando algas invasivas, aspirando restos de comida, y veo algo que se mueve, apenas el movimiento ya que el animal es tan pequeño; el movimiento lateral típico de un cangrejo, o el ondeo de un tentáculo miniaturo. Algo nuevo que ahora vive en el acuario.

Y tengo que seguir con el mantenimiento, pues no puedo abandonar a mis amiguitos, no sin llevarlos uno por uno al sitio adecuado de su zona intramareal.

Isópodos verdes llegan cogidos tan fuertemente al alga parda, Fucus spp., tan apegados que no los veo, ni cuando estoy enjuagando las algas antes de instalarlas en el tanque.

Foto: # 1, 2: Isópodo de Fucus, Idotea wosnesenskii. Visible sobre un alga roja. Nótense los ganchitos en cada una de las catorce patas; estos se agarran tan fuerte al alga que ni las olas ni yo al trasportarla logran despegar el animal.

Y han crecido en el acuario una generación de isópodos muy pequeños.

Fotos # 3, 4: Isópodos en una concha de ostión. Los más grandes miden aproximadamente 5 mm. de largo. Siempre que saco una concha cualquiera del tanque, la encuentro cubierta de un gran número de esto, todos corriendo de acá para allá, siempre con mucha prisa.

Foto # 5: en una concha de mejillón hay dos de estos isópodos miniaturos y dos amfípodos; estos son los que se doblan, haciendo medio círculo.

Y esto: lo vi por primera vez hace un mes o más, apegado al vidrio debajo del nivel de la arena. Desde ese punto de vista se parecía a una lapa chica, pero la forma era diferente. Con una lente de aumento lo examiné y pensé que tal vez sería un quitón juvenil.

Hace quince dias estaba, ya más grande, en una concha de ostión y si era un quitón. Y hoy lo encontré en una piedrita. Lo saqué del tanque, manteniéndolo siempre en el agua, y le saqué una foto.

Foto # 6: Un quitón "de madera", Mopalia lignosa, creo. Con dos anémonas.

Parece que si es un quitón de madera. Si es así, puede crecer hasta los 8 cm.; por ahora mide 1.7 cm.

No estaba contento con su viaje. En cuanto lo regresé al tanque se fue a esconder bajo la concha de ostión de nuevo. Estos son animales tímidos que se esconden en la parte inferior de las piedras y las conchas de mar. Allí, no se mueve mucho; se mantiene allí tranquilamente comiendo algas y diátomos. Le gusta la lechuga de mar, Ulva spp.; mañana, que va a ser un dia con marea muy baja, si el tiempo lo permite, voy a la playa a buscarle un poco de lechuga marina para "Woody", y algo de hierba Zostera para los ermitaños, kelp para los cangrejos, y unos bálanos para los caracoles carnívoros. Y ...

Y quien sabe que otra criatura se subirá de pilón.

Colours under rocks

What a difference a few metres make! I've been on this beach (Willow Point), flipping rocks at low tide before, but this time, the tide was the lowest I've seen it. The last time, I saw crabs and small snails and hermit crabs and barnacles. Not much else. This time, every rock had a diverse community on the underside.

Wosnesenski's isopods, multi-coloured snails, limpets, a tiny, tiny clam, barnacles, spiral tube worms, unidentified eggs, and a possible red chiton.

I was chasing Wosnesenski's isopods; they're big and visible, but very fast, very motivated to get back underneath a stone. None of them stop to challenge me, like a shore crab will.

"I'm going to pinch you and crunch your shell! No matter how big you are!"

(Aside: what's that weird thing under the clamshell on the upper left?)

Wosnesenski's isopod (Pentidotea wosnesenskii) stubby isopod (Gnorinmosphaeroma oregonensis -the name is longer than the beastie), and red chiton.

This isopod ran away, as they do, but exposed a stubby isopod and a red blob, which the camera saw better than I did. Stubby isopods are small, at most 1 cm long, usually less.

Stubbies. I think there are two of them, stacked. Two flatworms and their eggs, a barnacle, and a small, red chiton.

Chitons are fairly common in the lower intertidal zone. So far, I've seen the giant Pacific chiton (up to 14 inches; the ones I've seen were between 5 and 6 inches long), the beautiful red-lined chiton, the woody (to 8 cm), the mossy (10 cm), and some hairy species, so buried under their overgrowth of algae that they were unidentifiable. But I hadn't seen one so small, and so red. I don't know the species; none of the 30 species in my encyclopedia seem to match.

A more usual find; a woody chiton, still very small.

Using all three eyes

The camera sees more - and less - than my eyes do. Flipping rocks along the shore, left-handed, with the camera in the right hand, finger on the shutter button, I disturb crabs, who scuttle quickly under the next-door stone. Flip another; crabs. Another; more crabs. One stops to threaten me, pincers raised. "Come on, see if you dare!" I turn the camera in her direction, and she changes her mind and joins her friends under shelter.

Another stone. More racing crabs. Once they're gone, I see slow movement; flatworms. The camera sees them, unless the light is just exactly right, as brown smears. My eyes see the movement, the merest hint of it, going in a different direction than the slither next to it, the next flatworm.

Whelk egg cases, spiral tube-worms, and flatworms on the underside of a stone.

Wosnesenski's isopods, one lying upside-down for some reason, showing off his 14 legs. And a pair of crabs.

Sometimes, there's a nano-second of flurry, a miniscule splash; a baby sculpin, an inch long, gone to ground, now invisible. Maybe the camera will see him; I won't. But I saw the splash.

Some animals are only recognized, in these surroundings, by their movement. I learn to see them; the merest rise and fall of a limpet under the seaweed gluing herself down to the rock while the light threatens her; the split-second flip-flip-flip of a gunnel, the shrinking of an anemone, the characteristic sideways scuttle of a miniature hermit - snail shells don't move like that without a hermit resident; the writhing of a polychaete worm becoming one with the mud underneath, the squirting of a clam retreating deeper into the mud. The camera never sees those.

Spiral tubeworms, flatworms (the light was right- look for the eyes!) and a limpet, still on the move. I don't know what that tiny thing with the striped back"bone" on the stony patch in the centre is.

My eyes miss the very tiny critters. My reading glasses are in my pocket; they get in the way when I look through the viewfinder, and the light is too bright to see the screen. So I point and shoot, looking for the green square that says the auto-focus has found something interesting. Or find a safe, non-painful (broken barnacles are sharp!) place to kneel so that I can get my head down a few inches from the stones and look through the viewfinder.

White shells, a sea of white shells; must be barnacles. The camera knows better. Waving seaweeds; no, the camera discovers tentacles or antennae. Or a mass of worms.

The camera saw these. I didn't.

This photo includes two masses of ribbon worms; the upper one is a knot of Paranemertes peregrina (p. means wandering), the purple ribbon worm, with a very purple body and a creamy belly; the orange ribbon worm, Tubulanus polymorphus; and the green ribbon worm, Emplecotnema gracile, with its green top and yellow belly.

The lower knot appears to be all green ribbon worms.

And there are three flatworms and a trio of crabs.

Sometimes things are easier; I find an underwater species tossed up to die on the shore. These I can pick up and move to a better background.

Unidentified species of hydrocoral. Notice the yellow "bud" at the tip of the branches.

Habitat for the critters found above. The stripes parallel to the shore are probably old glacier tracks on sandstone.

The secret lives of stubbies

Isopods: the name means "same legs". Because their 7 pairs are all more or less the same, as compared to the hermits and crabs, whose "legs" can be anything from huge claws to rudimentary grabbers and tiny brooms.

Stubbies, Gnorimosphaeroma oregonensis, on the underside of a rock.

The stubby isopods hang out in large groups, hidden away out of the glare of sunlight. When I turned over this stone, several dozen scrambled for cover. A handful rolled up into balls and rolled away. These few opted for pretending to be part of the rock. The largest are about 1 cm long.

Isopod females carry their young internally until they are ready to join the crowd. They do not have a swimming larval stage, like crabs do. The tiniest ones in this group of stubbies are youngsters, mostly female. After they reach adulthood and raise a family, they become males, large enough to compete for smaller females.

Wosnesenski's isopod. 4 times the size of a large stubby.

Crustaceans molt. We're used to seeing the remains of a crab molt on the beach; the upper carapace, sometimes with legs and lungs still attached. Hermit crabs back out of their hardened upper body shells, dragging the eyes and legs after themselves. I find their empty exoskeletons floating near the bottom of my tank, look around, and find a new-looking, clean, and slightly larger hermit, often in a new, larger shell.

The isopods are the only crustaceans that molt in two stages; first, they squirm out of the rear section, then later, back out of the front, eyes, antennae and all.

As adults, isopods differ from other crustaceans in that moulting occurs in two stages known as "biphasic moulting". First they shed the exoskeleton from the posterior part of their body and later shed the anterior part. (Wikipedia)

Crabs and hermits and other hard-covered invertebrates mate in the brief interim between the molt and the hardening of the new exo-skeleton. Isopods mate in between the two half molts.

(It always makes sense to re-read Wikipedia articles: I often notice things I had missed on an earlier read. This time, I noticed the line about molting, then searched Google on isopod molting and found out about the mating strategy.)

Caught in passing

I was watching hermit crabs in the aquarium when a red worm zipped by.

Spiny polychaete. Each "foot" is tipped with a brush, and armed above with a long spine.

He's tiny; on the right, three copepods are playing. They're about a millimetre long. The round dots along the edge of the shell are oyster eyes. And I don't know what that yellow and black striped creature (or tentacle, or foot) is, peeking out from between the folds of the oyster shell.

A large isopod reached out from a seaweed clump to investigate a mass of green-centred bubbles, probably disintegrating algae.

These isopods are plentiful under rocks and clutching rockweed in the intertidal zone. Sometimes they come home with me; they live happily in the tank for a while, until a crab catches them for dinner. As long as there is at least one branch of rockweed, they stay out of reach.

Pickle bug

I was pleased, last week, to get a recognizable photo of one of my rockweed isopods, on the far side of the tank. They are usually so tightly clasped onto the seaweeds that they become almost invisible, so that I can lift a rockweed out of the water, rinse it off, place it in a bowl, clean the tank, and replant the rockweed without noticing the isopod I've been handling until it decides to swim to a different clump of weed.

Last week, I was surprised to discover that there were two of these in the tank. Yesterday, cleaning the tank again, I found a third; no telling how long the three have been there.

And this time, one decided to explore the orangey algae collar of the big anemone, right up against the glass, where I could get a good look at him.

He's about an inch and a half long, not counting the antennae.

The tail end is rounded outward; the similar eelgrass isopod has a bite taken out of the tail.

These isopods have 7 legs on each side, each ending in a sharp, incurved claw, which they use to hold tightly to seaweeds waving in the current. They prefer rockweed or kelp, but I have found them on mud under rocks, on sea lettuce, and now on the delicate red algae around the neck of the anemone. They eat algae and other detritus.

The colour varies, according to the weeds they've been eating; the smallest of the isopods in my tank is a dark brown; this one is the brightest green.

Males are usually larger, and have fatter legs. The female broods her young; I'm going to be watching the smaller two closely, to see if I can catch one in berry.

Head shot, showing the kidney-shaped eyes, and one of the flat, hairy palps.

These are also known as kelp isopods, Wosnesenski's (or Vosnesenskys) isopod, olive-green isopod. And a name I hadn't seen before; pickle bug, because of the shape and colour of the greenest ones. The scientific name is Idotea wosnesenskii.

While the sun shines

The morning sun is high enough these days to reach my kitchen window and bounce its light off the wall back towards the aquarium for a few minutes; I took advantage of it to get some quick photos with natural light.

First shot. I didn't even bother to turn off the pump; no time to waste. Three anemones, an oyster, red and green seaweeds.

Sun shining through the tentacles of a little pink-tipped anemone.

The second pink-tipped anemone, with barnacles.

The burrowing anemone, reaching towards the light. She always wears this collar of red seaweed these days, and it's usually hiding a fair collection of neighbours; hermits, copepods, sometimes a crab, snails, worms, isopods, and limpets. Can you see the hermit? And the three strands of snail poop?

This rockweed isopod was poking around on the far side of the tank. There are two of them; I don't know how or when they arrived.

Limpet working on new growth on the glass. (I had scrubbed it well the night before, but algae grow quickly.)

And then the sun climbed over the roof and left the tank in dim light again.