Turtle? Butterfly? Neither.

 If I had seen this crab on the shore (and maybe I have), I wouldn't have recognized it as a crab. Just another piece of broken clamshell, unless it was moving. But in the aquarium, I got to look at it from the underside. And it is obviously a crab, but it seems to be wearing a borrowed carapace, too big for it, as if in imitation of the hermit crabs.

No, that's the carapace he grew himself. So wide it can hide all his legs and that fat right claw.

Cryptolithodes typicus, the butterfly or turtle crab.

Sometimes he is given the name, "umbrella crab", although this properly belongs to a relative. But the carapace does look umbrella-ish. He is also called, properly, the turtle crab, because he can hide completely under the carapace like a turtle does. Or he's the butterfly crab; the reason for that name shows up in the next photo. His Latin name means "typical hidden stone".

Other characteristics, those that differentiate him from the "true" umbrella, are the ridges on the edges of his abdominal plates and the knobby, stubby claw.

And here's a leftover molted carapace:

Butterfly crab carapace

I puzzled over this for a while. Was it a crab molt, was it a broken piece of something else; if it was a crab molt, what species? And it turns out it's the same species as the one above. They come in a variety of colours, from white (especially when young), to red (especially the males), to dull greys and browns. And they may be spotty or streaky or, as here, with the central portion a distinct contrast with the wings, which is what gives them the name "butterfly crab".

iNaturalist has many photos of this crab, showing the variety of colours and patterns. Check them out here.

They're an intertidal or shallow subtidal species, so I probably have seen them without recognizing them. Perfect camouflage.

A couple more crab photos, "normal" crabs, the ones I'm used to finding: see how the body fills out the entire space under the carapace, so the legs can never be hidden. These crabs have to depend on speed and shelter to escape predation.

Rock crab?

Help! There's an anemone after me!

~~~~~~~~~~~~~

Si hubiera visto este cangrejo en la playa — y tal vez sí lo he visto — no lo hubiera reconocido como cangrejo. Más bien parece un pedazo de concha de almeja roto, si no está en movimiento. En el acuario, lo llegué a verlo desde abajo. Y se ve claro que es un cangrejo, pero parece que, al costumbre de los ermitaños, lleva un caparazón prestado, demasiado grande para el cangrejito debajo.

Pero no; ese es su propio caparazón. Un caparazón tan ancho que puede cubrir todas sus patas y ese quelípedo derecho gordo.

Foto: El cangrejo Cryptolithodes typicus, el cangrejo "mariposa" o "tortuga".

A veces recibe el nombre de "cangrejo paraguas", aunque este nombre más bien pertenece a un pariente suyo. Pero de veras, el caparazón da la impresión de un paraguas. Más aceptados son los nombres "cangrejo tortuga", por la manera en que puede esconderse completamente debajo del caparazón, o "cangrejo mariposa", lo que se explica con la siguiente foto. Su nombre científico significa "piedra típica escondida".

Otras características, que sirven para identificarlo en contraste con el cangrejo paraguas verdadero; los bordes levantados de las placas de abdomen, y los quelípodos cortos y nudosos.

Foto: un caparazón abandonado después de una muda.

Este caparazón me dejó perpleja por un tiempo. ¿Era una muda de cangrejo, o un pedazo de otra cosa? ¿Si era una muda, de que especie? Y resulta que es de la misma especie que el primero. Aparecen en una variedad de colores, desde blanco (especialmente los jóvenes), hasta rojo (especialmente los machos) y gris o café, claro o oscuro. Y pueden tener manchas o rayas o como aquí se ve, con la porción central de un color diferente en contraste con el de las "alas". De donde recibe el nombre "cangrejo mariposa".

En iNaturalist hay gran número de fotos de este cangrejo, demostrando los diferentes colores y diseños. Haz clic aquí.

Esta es una especie que habita en la zona intramareal o en las aguas de poca profundidad, así que probablemente los he visto sin saberlo. ¡Camuflage perfecto!

Y un par de fotos más, estas de cangrejos "normales", los que acostumbro encontrar; ve como el cuerpo llena todo el espacio debajo del caparazón de manera que las patas nunca se pueden esconder. Estos cangrejos dependen de velocidad y la protección de piedras o hierba marina para escapar a los depredadores.

Foto:

•  un cangrejo "roca"?
• —¡Socorro! ¡Me quiere atrapar una anémona!

Dressy crabs

 At least these are identifiable as crabs. But anything beyond that is a wild guess.

Decorator crab. I think. Maybe.

Crab with pink hat.

This guy's "hat" is probably a pale sponge. And he's wearing some spiky algae. The apparent eyes, those round spots just under the sponge, are not eyes; the eyes are on stalks close to the rostrum, that pointed structure making a roof over his mouthparts.

And what on earth is this?

All eyes.

It is very tiny. I saw only the eyes; the camera picked up other details, the rostrum and some white stuff behind. Part of the eye guy, or something else? I can't tell.

I'm going to make a pest of myself in the aquarium with my questions.

~~~~~~~~~~~

Por lo menos, puedo reconocer que estos son cangrejos. Pero más de eso, tengo puras conjeturas.

Foto #1: un cangrejo decorador. Creo. Tal vez.

#2: Cangrejo con gorro. La sustancia color de rosa pálida creo que es una esponja. Además lleva un poco de alga. Lo que parece ojos, las manchas redondas, no lo son. Los ojos se sostienen sobre pedúnculos, y están justo al lado del rostro, que es ese techito puntiagudo que da sombra a las partes de la boca.

#3: ¿Y esto, qué es? Muy pequeñito. Yo no más vi los ojos y la cámara registró los otros detalles, el rostro y algo blanco atrás, que puede ser parte del ojudo, o otra criatura. No lo puedo distinguir.

Tendré que hacerme una plaga en el acuario, haciendo preguntas.

Fighting crabs

 A few years ago, on a hot summer afternoon, I was watching the tide roll in over a rocky breakwater. As the water rose between the rocks, crabs started to come out from their hiding places. More crabs and more, where a few minutes ago there had been no sign of life, just the hot, bare rocks.

The water rose until it reached a dried kelp stipe, cast up to bake on the rocks. And this surprised me: immediately the crabs attacked it; all the crabs, jostling and scrambling over each other to get at this dried kelp. More came out from hiding, dozens and dozens more, all of them grabbing at the stipe, fighting for a spot, pushing each other out of the way, tearing off bits and eating them. As the tide covered more of the length of kelp, so did the crabs until there was no kelp to be seen, just this dancing mass of crabs.

I should have thought of this sooner. My hermit crabs like kelp, too, and I would bring them fresh kelp from the shore. But cut kelp quickly turns slimy; I could feed them only a small piece and throw away any extra. And then, last fall I remembered the happy crabs.

So now I slice a long stipe into thin circles and dry it. And every couple of days I give the hermits and crabs a couple of dried slices. The first batch lasted them all winter; now they're starting on a stipe I dried a couple of weeks ago. 

Hairy hermit and his kelp treat.

One of the tiniest hairy hermits, with his scrap of kelp.

And a watchful crab, ready to fight for her meal, if necessary.

~~~~~~~~~~~~~~~~~~

Hace unos años, en un verano caluroso, estaba en un rompeolas mirando mientras subía la marea. Cuando el agua empezó a cubrir las rocas, aparecieron los cangrejos que hasta entonces habían estado bien escondidos, fuera del alcance de los rayos del sol. Más cangrejos, muchos cangrejos, donde hacía poco no se veían señales de vida, solamente esas piedras resecas.

El agua subió hasta que alcanzó un tramo del estipe de quelpo ya bien seco, tostado por el sol allí expuesto sobre las rocas. Y esto me sorprendió; en cuanto el agua tocó el quelpo, los cangrejos lo atacaron; todos los cangrejos, con gran entusiasmo empujándose, trepándose uno encima del vecino para llegar a este pedazo de quelpo seco. Salieron más de sus escondites, docenas más, todos tratando de agarrar el quelpo, peleando con los que se pusieron en su camino, defendiendo su sitio con ánimo mientras arrancaban pedazos para comer. Mientras la marea cubría más del quelpo, también lo hicieron los cangrejos, hasta que no se veía nada del alga, solamente esa masa pululante de cangrejos.

No sé porque no pensé en esto antes. A mis cangrejos ermitaños también les gusta el quelpo, y yo les traía pedazos desde la playa. Pero el quelpo cortado pronto se hace baboso, y solamente les podría dar un pedacito y tirar todo lo demás. Hasta que el otoño pasado, me acordé de esos cangrejos felices.

Y ahora me traigo todo un estipe largo, lo corto en rebanadas delgadas, y lo pongo a secar. Y cada dos o tres dias les doy una o dos rueditas de quelpo a mis criaturas. El primer estipe nos duró todo el invierno; ahora empiezan con el segundo. Y muy felices están.

Fotos: 

1. Un ermitaño "peludo" Pagurus hirsutiusculus, con su pedazo de quelpo.
2. Uno de los más pequeñtos, también comiendo quelpo.
3. Y un cangrejo hembra, algo preocupada por pensar que yo le puedo quitar su hallazgo. Lo defenderá con esas pinzas, si llega el caso.

Empty suits and a walk on the sand

The crabs I see on our beaches and rocky shores are mostly shore crabs: green shore crabs and purples. Lower down on the beach, in the tidepools and on pilings under the wharfs, the kelp crabs take over. In deeper water, local crabbers find Dungeness crabs. On the stretch of shore I visited this last low tide, I found the molted carapaces of two other species. 

Just the carapace. Graceful crab, Cancer gracilis.

To identify these crabs without access to the pincers, count the "teeth" on the outer edge of the carapace and the bumps between the eyes. The Dungeness crab has 10 teeth on either side, with the carapace at its widest point at the 10th tooth. This one, the Graceful crab, has 10 teeth, but the widest point falls at the 9th. The adult crab grows to about 5 inches across; the Dungeness reaches 11 inches.

Helmet crab, Telmessus cheiragonus.

This is a crab molt; the crab opened his abdomen and crawled out backwards, eyes, legs and all, leaving his too-small suit behind on the stones.

And there was a kelp crab, out for a walk a good distance from any shelter. Unusual behaviour for one of these.

Afternoon stroll

And not a crab, but a hermit crab:

Totally invisible.

I thought this was an empty shell. I could see no sign of pincers or antennae. I brought it home; my hermits are always needing new shells as they grow out of the old ones. But at home, while I sorted eelgrass, a hermit poked his legs out. A grainy hand hermit, of course; these are the ones that love to hide deep inside a shell.

~~~~~~~~~~~~~~~~~~~~~~

Los cangrejos que encuentro en nuestras playas son principalmente los cangrejos de la costa, los verdes y los morados. En la zona intramareal más baja, en las pozas intramareales, y en los pilares debajo del muelle, se hallan los cangrejos kelp, y mar adentro, los grandes Dungeness. En el tramo de la costa que visité el otro dia, encontré los caparazones mudados de dos especies de cangrejo que no había visto aquí antes.

Primera foto:  el caparazón de un cangrejo "gracioso", Cancer gracilis.

Se pueden identificar estos cangrejos contando los "dientes" al borde del caparazón y las protuberancias entre los ojos. El cangrejo Dungeness tiene 10 dientes de cada lado, y el caparazón alcanza su mayor anchura al nivel del décimo diente. El cangrejo gracilis tiene los diez dientes, pero el último es muy pequeño, y el noveno marca la amplitud mayor del caparazón. El caparazón del cangrejo gracilis llega a medir 12 cm., miehtras el del Dungeness puede alcanzar 28 cm.

Segunda foto: un cangrejo "casco", Telmessus cheiragonus.

Este es la muda entera. El cangrejo abrió su abdomen y se arrastró hacia atrás, saliendo del caparazón viejo, del revestimiento de los ojos y las patas y todo, y ahí lo dejó todo en la playa, ya que no le servía pues el cangrejo había crecido.

Tercera foto: un cangrejo kelp, caminando sobre la arena, bien lejos de cualquier escondite. Generalmente, estos cangrejos se quedan bien escondidos.

Y la última foto: no es un cangrejo, sino un cangrejo ermitaño. Pensé que era una concha vacía ya que no veía ningún señal de vida adentro. La traje a casa porque mis ermitaños siempre están en busca de conchas nuevas mientras van creciendo. Pero en casa, mientras preparaba las algas para el acuario, si no sale un ermitaño de la concha dizque vacía. Un ermitaño granosimanus, por supuesto; estos son los que siempre quieren esconderse.

Of stones and crabs

When I go out without a fixed end point, I usually go north or west, away from the cities and the noise, the road crews and the traffic. This Wednesday I decided to break the pattern and head south. I didn't know where I was going; somewhere beyond Comox, 45 minutes to the south of my place; somewhere between the Comox valley and Union Bay, probably.

I'd barely gotten to Royston when I saw the sign: Royston Seaside Trail. Destination found. I drove to several spots along the trail, going down to the shore in each spot. The tide was low and going out; I walked to the water's edge in each location.

The setting. Royston is on the far side of a bay with Comox and Courtenay on the other two sides.

The shore is flat and stony; there was no sand, some mud. Very slippery mud. After three steps, it slithered away underfoot and almost threw me. I moved back to the rocks.

The stones here are hard, angular, sharp-edged, firmly glued to the underlying mud. And everywhere I looked, tiny crabs were scuttling about, sometimes stopping to threaten me.

It was low tide, and the sun was hot, so I was surprised to see so many crabs out in the heat; usually they find shelter under stones or seaweed when the water goes away. Not here; maybe because the stones are so solidly embedded, maybe because there was almost no seaweed, except for a few patches of bright green stringy algae and the occasional lonely rockweed.

In an area with rounder rocks, a green shore crab finds a bit of shade.

This poisonous-green algae formed mats here and there. Possibly Urospora pencilliformis.

I collected a stone with barnacles for my snails at home, and wrapped it in some of the green algae; the crabs and hermits would appreciate it. Before I wrapped it, though, I shook out the seaweed, scattering tiny snails and crabs. Still, a dozen miniature shore crabs somehow made it home unobserved. They're in my tank now; I'll have to return some of them (the ones I can catch) back to the shore.

There were crabs everywhere. In this patch, I can see at least 6 crabs; more will be hidden under the rockweed and hair algae.

The other residents of the shore seem to be mostly barnacles and snails, and a few oysters. I looked, but found no worms, no anemones, no tiny swimmers. And surprisingly, no hermit crabs, which are usually in abundance where there are many snails to provide shells.

This crab molt probably came from lower in the intertidal zone. A young Dungeness crab, Cancer magister.

Another Dungeness crab, this one underwater. So clear the water!

There were a few patches of sandstone like what we find around Campbell River.

The trail website suggests that many of the rocks on this beach are not original to the site.

Starting in 1911, steam locomotives hauled logs from logging camps throughout the Comox Valley to the Royston log dump. ... Where it approaches Hilton Road, the railway grade was constructed in the intertidal area. From the end of Chinook Road, a mile long wharf extended into the water.  Logs were tipped off the wharf until the early 1950s when the railway stopped running. ... The wharf was taken down and replaced by a breakwater in the 1950s. ... The rocks that can be seen within the intertidal area during low tides most likely originate from the fill material placed to construct the railway grade. (Royston Seaside Trail website)

More rocks, the breakwater, and - what's that?

About those rusting hulks, tomorrow.

When purple is green

When they're babies, purple shore crabs come in all colours from creamy yellow to green to red or even bluish. Most adults are purple or green.

Green shore crabs are mostly in shades of green, although some are dark red or purple. Otherwise, they look like purple shore crabs and live under the same rocks. It's usually easy to tell them apart, though, because the purples have polka-dotted pincers. The greens have plain pincers.

But then, there are the colour morphs. Some purple shore crabs are all over green, and they don't wear polka dots.

Green purple shore crab with a cracked carapace.

(I don't know how she got hurt, or how old the injury is. One of my students, a 9-year-old boy, brought her to me as is. He says that's how he found her. She was quite lively, in spite of the damage.)

So how do I know she's a purple? Because green shore crabs have hairy legs; purples are "nude". Their Latin name is Hemigrapsus nudus.

Side view. Clean-shaven legs.

She only stayed on my hand for a few seconds, then she scrambled off and dropped into the rocks. But before she went into hiding, she stopped to warn me off:

"Go home, huge monster!"

... thereby showing me her green, non-polka-dotted pincers.

These crabs lose pincers and legs with no noticeable disruption of their lives. The cracked carapace won't heal, but at next molt, she'll have a nice, new one; she should be ok.

Supercritters

High above the rocks and surf, a diver waits for the right moment, the right wave. Repeatedly, he tenses as if to leap, then relaxes. Finally, the wave seems right; he's off!

Free fall.

Once down, he faces the next challenge; reaching the rocks he has to climb without being pounded to a pulp against them. Again and again, he turns and dives through the incoming wall of water; it's too high, too close, too solid. In a brief moment of calm as the ocean gathers itself for a fresh onslaught, he reaches the rock face and scrambles quickly up to safety.

It seems that nothing made of flesh could survive the relentless pounding of tons of water against immovable rocks.

Below the dive platform

Spraying, rushing, boisterous water.

But there is life, even in this tumult.

Seaweeds and maybe anemones in the surf.

At the far end of the beach, behind a breakwater, I waded out at low tide one day to look at some of the growing things on the rocks. The greenery on the rock above is a variety of rockweed; some of the darker things, at least on the breakwater, seemed to be tightly compacted anemones, a dark, spiky weed, and some sort of soft encrusting growth. A brighter green hair also grows on these rocks; short strands, probably kept trimmed by the rushing water.

Back to the rocks below the dive tower:

Rocks with assorted seaweeds.

But look what showed up when I zoomed the photos to full size!

Do you see the crab on the far right?

Zooming in even more. I don't know what those little critters are; there were others scattered around the seaweed areas.

A bit of sandstone sculpted by the waves among the stones at the base of the seawall. The waves reach this area, pounding downward, then draining quickly away; the current is swift and strong.

Zooming in. Long-legged crabs and tiny snails.

In another area of the beach, I collected some of those tiny snails; a fair number of them were hermit crabs. Some of these on the sandstone seem to be hermits, too. How they hold on as the water comes and goes, I can't imagine.

One of the hermits. About the size of a grain of rice.

And the next wave rushes in. The crabs and hermits and snails hold on; it's what they're used to.

Hunger is the best spice

Another Campbell River post

On a beach at the south end of the Campbell River Rotary seawalk, there is a tidewater pool, which looks artificial; a square dredged out of the stony beach, with not much to say for itself as yet. We walked out to the far side of this at low tide. The scenery, looking out across the water to Quadra Island, was beautiful, as always. But the beach was mostly clean rocks, with nothing much living underneath, not even seaweed.

Dry rocks and tiny barnacle shells

Periwinkle snails gather just above the water line.

It was difficult walking on the loose stones, and Laurie's injured leg was bothering him by the time we got to the water's edge, so he sat on a rock and I entertained myself looking for interesting stones. At the edge of a small tide pool - grey rocks, grey stones, grey rocks - I noticed a half-dried, rotting kelp stipe, balanced on the stones. The tide was coming in, and as it reached the kelp, purple shore crabs began to crawl out from between the rocks to attack the kelp, which they began eating hungrily.

Not much else to eat on this beach.

As the water rose, more and more crabs appeared. The first arrivals fought off the newcomers, often knocking them back down into the water. Occasionally, three or more would be struggling together, legs and pincers intertwined.

I've seen crab fights before, usually over some choice bit of fish, but never over dry kelp.

I count 14 in this photo, of a small section of the kelp.

The green crab at the right is also a purple shore crab.

Green shore crabs (aka,  Oregon shore crabs) may be many colours, usually green, white, or grey. The purples are usually purple, sometimes green. I have a white one in the aquarium. They are distinguishable, sometimes, by the polka-dotted pincers (see the one near the left on the photo above) and by their hairless legs; the green shore crabs are hairy. (Here's a green and white green shore crab; notice the hairy legs.)

A sad post

I've been putting off writing this post, procrastinating in the futile hope that it will go away. It never works, does it?

November 26, three weeks ago: In the aftermath of the storm system that blew over most of BC, we went down to White Rock beach to see what had blown in. Just logs and broken plastic, it seemed. I wrote about it here.

I collected some fresh seawater for my critters in the tank at home; only about one litre, since I'd forgotten my regular 2 litre bottle. The water was dirty, with bits of eelgrass, wood chips, sand and muck, all whipped up by the crashing waves. It didn't matter; at home, as I have done before, I filtered it well, then let it sit for a few days for the fine silt to settle out.

The next week, as usual, I replaced 2 l. of the old water in the tank with new, including the latest beach collection.

All seemed well for a day or two. Then one morning, I noticed that my female crab was having difficulties. She stood on her head, with the hind legs swaying in the water, spread out. It took her a long time to right herself, but then she seemed ok. Until the next time I checked on her, when I found her caught upside-down in some seaweed. Something was wrong. (And she was in berry after their recent mating!)

The other two crabs seemed fine. But the big anemone was writhing and contracting oddly, making himself into a series of balls, then flat, then one ball with a pin-head tip, then a wide tip balanced on a pointed base, never opening tentacles to feed. A smaller anemone had disappeared entirely; so had the eelgrass isopods. I couldn't see any limpets, nor any pairs of amphipods waiting to mate. And the snails, those indestructible nasas and mud snails, were lying about, half out of their shells.

I hurried to change as much of the water as I could for freshly-prepared artificial seawater, adjusted for just-right salinity and temperature.

The next day, the anemone was worse; only a few snails were moving. Three clams were holding their siphons well out of the sand, about an inch high. I've never seen them do that before. And the big male crab was lying paralyzed, with legs stretched out and up, towards the back. The female was upside-down more often than not. The little male had disappeared.

I did what I could; removed everything to a "hospital" container with fresh water and clean stones, twice; watched and hoped. For a while, it looked as though the male would recover, but no, he relapsed. The snails died.

When the little male (that I had raised from crab babyhood) floated belly-up, too, I gave up. I drained off the water and replaced it with alcohol. They died quickly.

The baby, with anemone, in happier days.

What had happened? I have gone over and over each step of those days; the only source of whatever killed my tank would have been the water from the White Rock beach, where I have always collected water. And the only difference there would have been the after-effects of the storm. Was it contaminated rainwater from the city on the hill above the beach? Or something brought in by the wind and waves? I don't know.

(My previous die-off, not as complete, was caused by local pollution, blown in from next door. There was no sign of that this time, and the symptoms and species attacked were different.)

We have seen, on occasion, areas of the beaches we visit where large numbers of dead animals lie half-buried in the sand. (May, 2008, baby sand dollars, for example.) There are spots where dying clams lie thick on stinking mud; patches where we find no live animals at all, no matter how many rocks I flip, or how much sand I filter through. Sure, the areas recover, often, at least in part. Or become hosts to new forms of life, like the invasive mud snails that now cover much of the Boundary Bay beach on the Tsawwassen side. Sometimes they don't; years ago, Mom used to tell me of a beach on Vancouver Island where she could not find anything alive. It seemed impossible, back then; now not so much.

I have emptied and cleaned the tank and all the equipment, and hidden them away. I moved the furniture around so that the gap where they were doesn't show. I dumped everything previously alive in the garbage; I would normally bury it in the garden, as fertilizer, but I can't take the risk of poisoning the many animals that live in my soil. The sand will be spread, well washed first, in the most gravelly, polluted area of the vacant lot.

In the spring, I'll probably have the courage to start again. For now, I'm grieving.

I originally started bringing home beach invertebrates to learn something from them. More than just how to identify them, I wanted to know how they lived, how they interacted with other animals. I was even privileged to learn something about how they think, to see them show a reciprocal curiosity, watching me through the glass, responding to what I was doing. What kills them, how they suffer and die (that anemone's tortured contortions still break my heart!) is also something I have unhappily begun to learn.

It has made me very aware of what I buy, what I use and discard; it all enters the environment; it has the potential to do much damage. We can't turn back the clock; we've fouled our nest already, but at least I can keep from adding more poison to it.

Living in glass houses

...you don't get no privacy.

It was 10 PM, so I went to turn off the aquarium lights. As usual, I looked in to see how things were going; everybody happy? No disasters, no panics? All was calm.

But in the back, half-hidden beside the pump, a pair of crabs were getting ready to mate. I went for the camera.

A tangle of legs. Ma Crab's back. He's underneath her.

It's hard to mate when you're encased in a rigid shell. Crabs have to wait until the female molts; when her new outfit is still soft and pliable, there's a brief window of opportunity, not to be wasted. Her consort, finding her in the process of opening up, grabs her, belly to belly, and holds on until she backs out of the old shell. This may take several hours, or even days. He may even help her with the process; mainly, though, he's making sure he's at hand when the moment comes, and that no other male gets her. (Not a problem for him in the aquarium; there's only one other male, still too young, but he's not taking risks.)

Since his last molt, Pa Crab has been ready, swaggering about with full-size pincers, often frightening the smaller female. Not today; this morning she was hanging around near him. Now, she has allowed him to embrace her tightly. In the photo above, you can see his legs, the striped ones, (hers are spotted) hugging her. Both of them hold their pincers up and away from the body, claws open. They move about, slowly, getting comfortable. After a bit, they squirm down underneath the pump, where they are more private.

I don't know how long it will be until they mate.

Sculpted curves and "teeth" of the female's carapace. Two of her pincers, one of his.

A multi-species community

These are a few of the larger intertidal critters from the aquarium, photographed in the course of a tank census:

Three different shells; from right to left, Nassa snail, Asian mud snail, and barnacle.

Barnacles usually live attached to rocks or other solid materials. When they break off, the base gets left behind and the barnacle dies. Occasionally, one detaches from the rock without breaking. This one has most of the base intact, so it is still alive and feeding. Look closely to see the pale tentacles at the mouth.

The Nassa shell, on the right, has several round holes drilled through it, the work of a carnivorous snail, such as a whelk. Once the hole penetrates the flesh, the whelk injects paralyzing and digestive enzymes, which dissolve the snail inside. Often, once the shell is vacant, I discover the tentacles of worms waving from these holes.

Rockweed isopod, about an inch long. The flash makes the red seaweed glow in neon reds. Under normal lights, it is a bit paler than the burgundy Turkish towel that the isopod is feeding on.

The second isopod. Look closely; on the back, it is carrying a small shelled animal, probably a limpet.

Head of a polychaete worm, out looking for a meal. They rarely leave the sand completely, and retract almost instantaneously at any disturbance..

One of the round algae-eating periwinkles, with an amphipod taking a short break.

At least four species of snails live in my tank: Nassas, mud snails, periwinkles, and the tiny lacunas; these last may be so small that even with a lens, I am hard put to determine whether they are snails or sand grains until they move. Their eggs often come home with me on blades of eelgrass.

Underside, through the glass, of a very small anemone. 

This anemone sat for weeks on a stone, and then went wandering about. It has now hidden itself. I have never seen that "petal" effect on the base before.

The youngest crab, raised in the tank from babyhood. 

And my new mascot, found in a thrift store. $0.50; I couldn't resist.