Not-so-perfect housekeeping

 I do clean my aquarium. I really do. I scrub the walls every week with a toothbrush and a green dish scrubber (not metal, because it scratches the glass). I change the water and clean out old algae and vacuum up leftover foodstuffs. And scrub those walls.

But there's always a corner I miss, hidden behind an anemone I don't want to pester, or buried in sand that a crab just piled up in her everlasting building project. And whatever I want to look at always seems to hide right behind the messy corner.

I was watching a big, fat, shiny worm gobbling shrimp pellets, waiting for him to come within camera range (and he never did), and stopped to take a photo of a limpet eating, instead.

In the algae-infested corner, of course.

So frustrating!

I usually delete these photos if I can't clean them up, but I kept this one, as is. The limpet is eating the algae; that's why she's in that corner.

There are at least three species of algae growing here. First, those brownish spots. These grow really fast; within a week they'll cover all the walls of the tank. Several species of algae grow as crusts or microscopic dots; these are among them.

Then there's the brighter green algae; these look like the beginnings of sea lettuce.

And the small red spots: several red algae species grow in two stages. Turkish washcloth, Mastocarpus sp. for example, is a crust in one generation, and the next generation grows as a large, lumpy, towel-like blade. These slow-growing red spots may be Turkish washcloth. They have also colonized the water pump, and are very hard to scrape off.

The limpet isn't the only one eating algae; white spots are probably copepods; there's a larger one inside the shell of the limpet, wagging its tail. Good eating here, it says!

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Cada semana limpio el acuario. De veras, sí que lo limpio. Friego las paredes con un cepillo de dientes y un estropajo verde (no de metal, pues estos dejan marcas en el vidrio). Cambio el agua y saco algas viejas y aspiro restos de comida. Y pulo esas paredes.

Sin embargo, siempre se me escapa una esquinita, tal vez fuera de mi alcance tras una anémona que no quiero molestar, o cubierta de arena apilada por una cangrejita en su perenne afán de construirse escondites. Y luego, cualquier cosa que quiero mirar parece estar protegida atrás de esa esquina olvidada.

Estaba observando un gusano gordo y brilloso que se tragaba unas bolitas de camarón, esperando a que se acercara para que le sacara una foto, lo que nunca hizo, y lo dejé para tomar una foto de una lapa, que sí se presentaba a la vista. Pero, por cierto, en esa esquina llena de algas.

Casi siempre borro estas fotos, si es que no se pueden limpiar. Pero me quedé con esta, tal como está. La lapa está comiendo el alga; por eso se metió allí.

Hay por lo menos tres especies de alga que crecen aquí. En primer lugar, todas esas manchas cafés. Estas crecen rapidamente; dentro de una semana, cubrirán todas las paredes del tanque. Hay varias especies de alga que crecen como puntitos microscópicos, entre ellas, esas manchas.

Y luego hay unas hojitas de alga de un verde más vivo; parecen ser plantitas de lechuga marina, Ulva sp.

Y los puntitos rojos: varias especies de alga roja hacen el ciclo de vida en dos etapas. La toallita turka, Mastocarpus sp., por ejemplo, es una costra en la primera generación, y en la siguiente crece como una hoja grande con protuberancias, algo así como una toalla. Estas manchitas rojas en el tanque bien pueden ser la toallita turka. También se han metido a la bomba de agua, y son muy difíciles de quitar.

La lapa no es la única que está comiendo algas; los puntitos blancos probablemente serán copépodos. Hay uno más grande dentro de la concha de la lapa, meneando la cola. ¡Buen provecho!

Pod critters

I found a container of old shells, imported from who knows where, in a thrift shop. My hermits always need shells, and a bit of variety is always welcome (from a very human point of view). I brought home the shells, washed them thoroughly to remove any dust or foreign substances, soaked them overnight, boiled them in several changes of water, just to make sure, and added a few to the aquarium.

The hermits liked three of them. The rest, they rolled over a few times, then abandoned. Not the right shape, not the right taste, maybe just unfamiliar; whatever the reason, the ones I thought were prettiest were just not good enough.

Nothing goes to waste. Several orange-striped green anemones promptly moved into the unpopular shells, and an amphipod claimed another.

Cozy hiding place.

Amphipod, belly up. Feeling safe in there, it seems. And another five, in more usual poses.

These were down at the bottom of the tank, where the glass is much scratched from shelly critters trying to climb it. I blurred out or erased as many of the scratches as I could, without touching any of the copepods. There are dozens, small and smaller, some so pale they are almost invisible against the white shell.

The copepods trailing a second section are females with their egg masses. Some of these egg masses are definitely baby blue, others are white. But all the copepods have the one red eye, sometimes the only thing visible.

The orangey rods are probably limpet poop.

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.

Miniature water garden

No matter how often I scrub the inside walls of my aquarium, it usually has a haze of green and red algae growing back. And a school of copepods browsing among the plants.

I usually scrub it all off, just before I take photos. This time, I left things as they were.

Yellow-green and red algae start off with circular spots, becoming splotches. Green-green algae start off as blobs, become bigger blobs. Sand grains (regular fine beach sand) show the comparative sizes.

The copepods have one eye each. The ones carrying a round trailer are females; look closely at the one on the left: you can see the egg cases.

In the sand below, miniature polychaete worms scoot up and down their tunnels, waving twin tentacles to capture today's lunch, bits of detritus, scraps of the algae.

Here, the tentacles extend up into the water column. Food particles travel down a groove to the hungry mouth below.

My flash disturbed the worm and he shrunk back into his tunnel. But he soon forgot about it, and pushed back up to the surface to keep on fishing.

Today, I also saw a two-inch long green ribbon worm, out looking for prey. He's an active predator who likes barnacles. He hid in the sand before I collected the camera.

You are what you eat

Northern winters are tough on the little beasties that live at the intersection of sea and shore. Temperatures change, often drastically, in the course of a few hours. Storms toss whole colonies up on the beach, bury them in mounds of slimy, rotten eelgrass, drop logs on top of them. Cozy shelters in the seaweed are stripped bare; on the scoured stones, there is nothing left to eat, nothing to hide a scuttling crab from the myriads of hungry birds following the tide line.

My tank critters are spoiled. The temperature stays put; so does the water. Food drops from on high every day. There are no birds, and the cat doesn't relish getting wet.

Grainy-hand hermit on the remains of a kelp holdfast.

But even here, winter brings its losses. I comb the beaches year-round, searching for salad fixin's and gym equipment for the hermit crabs. In summer, there are bright sheets of sea lettuce, tall stalks of eelgrass, some loaded with delicious hydroids and diatom fuzz, knobbly Turkish towels and washcloths, long, green hair, stubby rockweeds, and more. But in winter? Bare stones, washed-out shreds of unidentifiable weeds, stripped of anything edible. And tea-leaf black, dried eelgrass.

In earlier years, the tank in winter gradually lost all its greenery, until the hermits wandered about disconsolately on bare sand and stone. I supplemented their diet with human food, sheets of green algae meant for sushi wrappings. They liked that, but it fouled the water.

The last couple of winters have been different. A red sheet algae established itself in the tank, and now grows as enthusiastically as the land plague, Himalayan blackberry. I have to keep cutting it back with every weekly water change. But at least there's something fresh to eat, and somewhere to climb.

Red algae is even trying to grow on the hermit's shell.

The change in diet has influenced the colours of some of the tank's residents. Red are redder, greens are browner. The colour of the shrimp's innards changes day to day, depending on his last meal; red today, transparent tomorrow.

And even the normally transparent copepods are striped with red and yellow. Look closely at the hermit above; there are a dozen copepods visible on his shell.

Three females with eggs, one male; the rest, I can't tell.

Most copepods have one red eye, a streamlined body, and a forked tail. The females carry their eggs around behind them; usually one pouch (Order Calanoida), sometimes two (Cyclopoida), one to each side. In the dark one at the lower left, the pattern is easy to see; red eye above, green bag beneath. The small, pale copepod at upper left may be a male of the Cyclopoida; his long, forked tail is just visible.

Drawing adapted from one by Jesse Cladgett.

With my nose to the glass

I've been watching some of the smaller life in my aquarium.

Like this female Calanoid copepod carrying her egg sac behind her.

The copepod is the basic food group for many marine organisms, including my anemones.

Some scientists say they form the largest animal biomass on earth. ... copepods almost certainly contribute far more to the secondary productivity of the world's oceans, and to the global ocean carbon sink than krill, and perhaps more than all other groups of organisms together. (Wikipedia)

In my tank, the copepods are about 1 mm. long, and visible only when the light hits them against a dark background.

The sand dollar was trying to climb the wall, pushing with the stripy spines until he was almost vertical. But there was nothing to eat on the wall, and he gave up and crawled back into the sand.

A tiny piece of broken crab shell, with the remains of a barnacle.

When the lined chiton came close to the glass, I was able to see the tiny hairs on its girdle.

I brought home two stones with big barnacles for the leafy hornmouth snails to eat. Once they were in the tank, the sand that came along with them got up and started to walk about. With a lens, I could see that they are snails, as small as fine sand grains. And in short order, they had all crawled down and merged into the sand on the bottom of the tank.

Small and smaller

Near the bottom of every marine food chain, we find copepods. In my tank, the anemones, the oysters, and the barnacles all depend on them. And I take them for granted; they're the flecks that I have to clean out of photos, the speeding speckles on the glass, getting in the way of what I wanted to see.

I went looking for them last night, instead.

The red algae provide a nice contrast, and give the copepods something to do rather than race around. This algae is growing on the big anemone's trunk. One of her tentacles is visible between the leaves.

A darker red seaweed, growing on a stone. Some, at least, of the speckles are copepods. Others are bubble; this plant collects a lot of bubbles.

Very tiny female copepod, with her egg sac. Most copepods have one red eye.

A different species, with black markings. The blue globe is her egg sac.

Another blue-green egg sac.

Copepods on the glass beside the anemone. I scrubbed this glass only three days ago, and it's already populated with assorted algae and unidentified "stuff". The copepods are busy eating it all.

One copepod on a relatively clean bit of glass. View from the underside, although they're so tiny, the innards show through from either side. Copepods without egg sacs are either males or juveniles. The males are usually smaller than females.

These were all very small copepods. Others in the tank, much more active, are twice the size. Their females carry double egg sacs, off to the sides, as in this photo from 2010:

This copepod is about 1 mm. long.

Planktonic copepods are important to global ecology and the carbon cycle. They are usually the dominant members of the zooplankton, and are major food organisms for small fish such as the dragonet, banded killifish, whales, seabirds, alaska pollock and other crustaceans such as krill in the ocean and in fresh water. Some scientists say they form the largest animal biomass on earth. ...
Because of their smaller size and relatively faster growth rates, and because they are more evenly distributed throughout more of the world's oceans, copepods almost certainly contribute far more to the secondary productivity of the world's oceans, and to the global ocean carbon sink than krill, and perhaps more than all other groups of organisms together. (Wikipedia)

The average adult right whale consumes about a ton of food a day, eating billions of tiny crustaceans called copepods that are packed with protein and calorie-rich oils. (Woods Hole Oceanographic Inst.)

Speck with eyelashes

I had this photo filed under "Best copepod so far". It was just another moving speck, maybe a millimetre long, on the inside of my aquarium wall. Nothing unusual; crowds of tiny critters dance along the glass; the larger ones are baby amphipods, and most of the smaller ones are the one-red-eyed copepods. Sometimes one, too tiny for my camera, looks more like a mite.

Tonight, I finally got around to cropping and examining the photo. And it's no copepod that I recognize.

Speck with eyelashes

For one thing, it has two eyes. The shape is right, but the tail is different. A female copepod often carries eggs at the rear, but in two fat sacks, not 4 pointed, hairy ones.

It doesn't look like an amphipod, either; an amphipod usually holds the antennae forward, not off to the sides. It almost always has long hind legs sticking out at odd angles from the back; when the tail end is curved inward, from a front view, it would be nicely rounded, with those legs well out to the side.  The eyes are too small.

I've spent hours looking for one like it.

I give up.

Help! What is this?

Tiny discoveries, and a mysterious bubble beastie

One of the anemones was getting itchy feet, wandering about, so I cranked up the camera to take his photo in transit. And got sidetracked by a few things I hadn't seen before.

First, the usual:

Hermit crab, with a tiny frozen shrimp. Nom, nom, nom!

Then, to smaller beasties:

A periwinkle snail. I keep trying to get photos of them eating.  This is the best so far, but a video would be better. 'nother day.

An amphipod, clinging to a blade of eelgrass, legs every which way. There are both green ones and brown in my tank.

Cropped down to show his marvellous compound eyes.

Amphipod eyes are compound as in other arthropods, and sessile, that is, unmovable.  Each eye consists of several hundred individual ommatidia, each of which has its own lens system, light-sensitive retinal cells, nerve leading to an optic ganglion, and each is thought to produce a single image.  Visual fields of adjacent ommatidia overlap, presumably producing good motion detection, but possibly less good resolution . . . it is probably safe to assume that they have good resolution and motion detection, and probably see in colour.  Hallberg et al. 1980 Zoomorphol 94: 279. (From A Snail's Odyssey)

And then I discovered a snail I didn't know was in my tank:

1/8 inch long, climbing on one of the thinnest eelgrass blades. I haven't identified him yet.

Smaller still; I went chasing limpets, to see if I could catch them eating. All around them, the copepods were cavorting:

Female copepod, carrying her egg case at the rear. She has one red eye, in the center of her forehead. (And when she is good, she is very good . . .) About 1 mm. long.

Something half the size of a copepod crawled off a limpet shell and went hiking up the glass wall.

A marine mite, about 0.5 mm.. I found 4 of them, all near limpets. The mess on its right middle leg is made up of diatoms and other debris.

Unlike the few insects and spiders which may be found in marine habitats but must breathe air, mites are able to absorb oxygen from the water so they can live at great depths. (From WallaWalla.edu Halacaridae.)

I didn't know this, so it seemed really weird to see this spider-like thing walking about underwater. It has 4 pairs of legs, like a spider, but holds one pair out in front as if they were antennae. Confusing little beastie.

Some marine mites are phytophagous (suck from plants/algae), some are predators, and some are parasites.

And while I tracked down these mites, with my hand microscope jammed up against the glass wall (and my neck twisted at an impossible angle; they insisted on hanging out on the wrong side of the tank), I noticed many even tinier groupings of bubbles on the glass. This was strange, because I'd scrubbed down the inside wall before I started taking photos. Where did these come from?

Two collections of bubbles and a copepod beside a limpet.

I thought I saw one group of bubbles move, so I zoomed in on it. But no; it was just there, not moving. And just as I was giving up, thinking maybe it was some sort of algae, it suddenly convulsed, waving 4 separate groups of bubbles about, like legs, for a moment, then settling down to rest again.

Other groups I checked showed the same behaviour. They come in different sizes and number of nodes or maybe branches, and they're all over the wall where the light is good, but not on the front (where my neck would be happier) with less direct light.

I haven't the faintest clue what they are. Help!

And I never did get a decent photo of the anemone. And now he's gone and jammed himself into an impossible corner. I hope he doesn't like it there.

On miles of sand, one little pink beastie

The supermoon, or more correctly, the perigee-syzygy* moon, when the moon is both full and at its closest approach to earth, causes greater than usual tides, both lower and higher. I checked our local tables, and sure enough, the tide dropped this weekend to well below the bottom line on the chart. And in the afternoons when we're free, to boot.

We went down to Boundary Bay Sunday afternoon. Far, far in the distance, halfway to Crescent Beach on the opposite shore, there was a narrow line of blue water. All the rest was sand, mud, and snails.

Looking from Centennial Beach area south to Point Roberts, and the Gulf islands beyond.

We took our time walking out. I was wading in all the tide pools we passed, looking at sculpins and hermit crabs. Halfway out to the edge, I was bent over trying to take a decent photo of a big skeleton shrimp, when a kid came along, slowed to see what I was doing (she couldn't see anything). She walked on, only a few steps, and stopped. Good thing; when I finally gave up on the amphipod, she called my attention to something pink on the sand. Otherwise, I would have headed off in the other direction, where Laurie was waiting for me.

Something pink.

I'd never seen one of these before, but my evenings of leafing through guides bore fruit; I knew what it was! A ghost shrimp! No, not a shrimp, I told the girl, a ghost shrimp. A Bay ghost shrimp, Neotrypaea californiensis, as I found later, checking the Encyclopedia.

I called and waved to Laurie, and he came over. The girl left.** We settled down to take photos. But what was happening?

He's backing out, away from that big pincer. We had caught him at the tail end of a molt.

Completely separated now, belly up and squirming rather awkwardly.

These animals live in burrows up to a couple of feet deep under the sand, their entrance and exit holes unnoticed among the millions of worm holes here. They rarely come out to the surface, where they are vulnerable; fish love to eat them. This guy must have come out to molt.

He flipped himself upright, and started inching backwards across the sand.

He's about 3 to 4 inches long; it's difficult to be exact, since he was curled up and kept stretching and folding. They may grow to about 4 1/2 inches long, and can live up to 16 years.

The long pincer on one side identifies him as a male. The females' pincers are more equal in length. At this stage, barely finished leaving the old skin behind, his pincer is thin, but he will pump liquid into it until it is bigger than the old one.

...in the males, the "master claw" can make up as much as 25% of the animal's mass – compared to only 10% in females – with the minor claw making up around 3% of the total body mass in both sexes. The enlarged claw is equally likely to be on the right side or the left side. (Wikipedia)

The big claw is not used for capturing prey; this critter feeds on detritus sifted out of the mud. Maybe it's just there to impress the females, or maybe he has to fight other males for her.

The ghost shrimp often shares his burrow with a variety of other animals; scaleworms, pea crabs, a burrowing clam, sometimes even small fish. And closer still, on his body he may have two species of commensal*** copepod and under the carapace possibly a parasitic isopod, Ione cornuta. We examined our photos carefully, looking for these.

And here they are! The little red circles with two "tails" are the copepod, Clausidium vancouverense. The "tails" are egg pouches.

If you look closely at the photos above, you will see many of these copepods, mostly on the legs and pincers. But there is a cluster of them also under the carapace, on the side. Kozloff says this is where they live, although a website calls them ectocommensals: "ecto-" meaning " outside, on the surface. Both are correct, it seems.

There's an excellent photo of one of the copepods on Flickr, showing the egg pouches stuffed with red eggs, here.

The parasitic isopod lives under the carapace, and would produce a distinct swelling on one side. There may be a small swelling where the copepods show through, but I'm not sure of this. Brine Queen has a good photo of a parasitised ghost with a discoloured swelling. On the Beachwatchers page, there's a male-female pair of the isopods themselves.

I picked up the abandoned pincer. And promptly dropped it; detached from its owner, it was still opening and closing, as if to defend itself. I collected it again, and brought it home. It was still moving about when I finally wrapped it in a tissue and put it in my pocket.

Sharp-pointed pincers. One tip is hooked; if it grabs you, you stay grabbed.

*Syzygy: line-up of moon, earth and sun, producing a full or a new moon. Pronounced SIZZ i gee. Here's a mouthful; PER i gee - SIZZ i gee.

**I wished I had realized what was happening sooner; I thought of calling the girl back to see what she'd turned up, but she was too far away.

***Commensal: living together without harming each other. (As far as we can tell.)

Creatures of the muck

It's why I love blogging; other bloggers are so helpful!

After a long day, I was dropping off to sleep at my desk, so I posted my photo of unidentified beasties, and went off to bed. In the morning, I found that Olivia and Tim had done my work for me: the critters are crab zoea! All I had to do was turn to the correct page in my textbook, and there they were. Thanks so much!

Every time we go to a beach bordering Boundary Bay, I collect a 2-litre pop bottle full of nice, clean, fresh, saltwater for the aquarium. I could mix up water and marine salt to the proper salinity, but that would come without the plankton that feeds the anemones and barnacles, and sometimes the crabs and hermits, too. (They love a nice, juicy amphipod, if they can get it.)

In the winter, this is a bit of a problem. In summer, I wade out, at least to knee deep, where the water flows clear. Not at this time of year; the water's just above freezing, and I like warm feet. At the shore line, specially at high tide, or this winter's high "low tides", the water is a thick soup, rich in rotting eelgrass and stirred up mud. So I bring home dark brown muck.

I could filter the water at home, but that would eliminate the plankton, too. (Boundary Bay mud is really fine stuff. I use a double coffee filter, and still some gets through.) So I strain out the big stuff, and let the rest settle overnight. When I pour it off, it leaves a residue that often, even to the naked eye, is hopping with life. This I examine under the lens, with a good light. There's no telling what amazing beasties will show up!

The last bottle of water had a dozen or so of these cute babies:

Crab zoea. Sort of look like birds, don't they?

They wiggled and jittered up and down in the water, mostly staying where the light was strongest. Even under the hand lens, they were hard to see; they looked like two-legged spiderlings. The microscope, at 40x, showed me the eyes, the long spine, the beak-like rostrum*, and the forked tail. *This is just barely visible on the middle baby.

(Yay! The little Sony accepts the homemade lens I used to use on my first camera; with it, I can get a photo almost as clear as what I saw under the 'scope. What fun!)

Drawing from MESA.

I was surprised by this; I didn't expect babies in the chill of mid-winter. Silly of me; a human notion that babies need warmth. I'm continually having to discard these un-examined "rules" for Ma Nature.

But that wasn't all to be found in my bit of sediment! There were a handful of egg-bearing copepods, of the kind that trails the eggs along in one clump at the rear. Most of the ones I see with eggs carry two egg bundles, off to the sides.

Image from here, by Carol E. Lee.

Then there was a baby shrimp, like the three I already have, but so small that under the lens, I could see only the eyes and a hint of transparent body. I didn't try to catch it for a macro; it looked far too fragile to be tampered with.

And this:

Unidentified. About 1 mm. long. Forked tail, two-tone carapace.

I couldn't determine what it is. Another copepod? An infant Nebalia? Maybe; the Nebalia pugettensis are common on this side of the bay.  I found a photo of a Cumella from Bellingham Bay, which seems to match, but I understood that these are more likely to be found in freshwater. Do you recognize it?

The shrimp, the mystery critter, and the copepods went into the tank; the shrimp may survive, but the copepods will soon be lunch. The crab zoea are being raised, at least for now, separately, out of reach of hungry anemone mouths.

Copepods in love

I've been chasing copepods in a few drops of sludge from my aquarium filter, trying to get a decent photo; they are so cute! So tiny! And so busy!

Busy, mostly, it seems, with starting families.

Mate guarding.

I found several couples like this one. One follows the other, nose to tail, never giving up. I assume the female is the one in front. Mostly, single copepods wander about almost randomly, now slow, now stopping, now dashing off in another direction. These pairs zip around at top speed, always connected.

Courtship and breeding is a long affair for such "simple" critters. First, the male must get a good grip on the female. He may (according to the species) need to convince her first, which might take up to two weeks. Persistence counts.

Once she has submitted, he produces a spermatophore, a container filled with sperm.  This he glues to her genital field. Then he may guard her, keeping off other males, until her eggs are fertilized.

After a few hours or days, she produces an eggsack or two (depending on the species, again). Now, she is obviously a female, even to us non-copepod observers; the eggsacks are almost as big as she is.

Tiny female. 0.5 mm, not counting the almost invisible part of the tail beyond the eggsack.

I couldn't tell if this one had one or two eggsacks. They were carried beneath the body, with the transparent, pinkish tail swishing back and forth over it.

These larger females (twice the size of the little ones, at 1 mm. long), carry the two eggsacks off to the side. They are not as strongly coloured, so often all that is visible in the muck are the two blue-green bags.

A few days later, those eggs will hatch and she will jettison the empty sacks. The spermatophore may still be attached, and will fertilize the next batch of eggs, too.

I trapped one last December: there's a photo here; it's an adult, either male or non-breeding female. The rest of the life cycle is described in this post.

The University of Oldenburg has more info, and some good close-ups. (Click on the labels at the bottom for more.)