The latest style in hats

In the lower intertidal zone, most of the crabs I see are kelp crabs. A few years ago, I noticed that many of them are wearing hats. Green hats, usually.

Kelp crab, on the beach. The hat is made of sea lettuce.

Another one, with a tiny green hat.

A week or so ago, a couple of very small kelp crabs hitched a ride home in some rockweed I had collected for my aquarium critters. I discovered them when I washed the rockweed, and carefully — they were so tiny and looked so fragile! — moved them to the aquarium. Later on, I looked for them, and discovered that the larger one had collected a piece of the rose algae that grows in the tank, and attached it to his head.

I was down on the shore again after a windstorm that had tossed up mountains of seaweeds on the shore. A treat for my critters: I collected two kinds of rockweed, a piece of Turkish towel, then some Turkish washcloth, two varieties of sea lettuce, a red bladed alga, a handful of eelgrass, and a piece of kelp.

As usual, I washed them at home, and planted them in the tank. I checked back an hour later, when I had finished cleaning the pump. And there was the larger of the two small kelp crabs, in plain sight. And now, he had added a piece of green sea lettuce to his red hat.

"Kelly" wearing the latest fashion in headgear.

Central Coast Biodiversity mentions that these crabs attach bits of kelp (but mine has sea lettuce and rose alga) to little hooks just behind their rostrum. CCB says they're saving them to eat later, but Kelly here has been wearing his red cap ever since the first day here.

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En la parte baja de la zona entre mareas, los cangrejos que más encuentro son los cangrejos "kelp", Pugettia producta. Hace unos años noté que muchos de ellos llevan una especie de sombrero hecho de alga verde, Ulva sp.

Aquí hay dos fotos tomadas en la playa en 2016.

Hace unas semanas, en un ramo de alga café, llegaron a mi casa dos de estos cangrejos, muy chiquitos. Los encontré mientras lavaba el alga, y los metí en el acuario.

Más tarde, al mirar el tanque, vi que el más grande — aunque sigue siendo bastante pequeño — llevaba un pedazo del alga roja que crece abundantemente en mi acuario.

El otro dia, una tempestad aventó montones de algas y hierbas marinas en la playa, todos rotos y revueltos. Junté una bolsita llena de varias especies para unos antojitos para los residentes del acuario: dos especies de alga café Fucus sp., una hoja de toalla turca, además de otra alga roja, toallita turca, dos variedades de lechuga marina (Ulva sp.), otra alga roja, un manojo de la hierba Zostera, y un pedazo de estipe de kelp.

Todo eso, lo lavé en casa, y luego lo añadí al tanque. Una hora más tarde, vi que el cangrejo kelp ya había arreglado su sombrero, añadiendo un buen pedazo de alga verde al rojo. ¡Muy bonito!

Central Coast Biodiversity menciona que estos cangrejos pegan pedazos del alga "kelp" (pero el mío está usando algas verde y roja) en unos ganchitos que tienen atrés del rostro. CCB dice que los están guardando para comer después, pero mi cangrejito ha estado llevando el sombrero rojo desde su primer día aquí, sin comerlo.

Underwater flowers

Pink tipped green anemone.

Under red algae, Pacific rose seaweed

I'm experimenting with different lighting setups for the aquarium. This anemone was hiding in the back, where I usually can't see it.

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Anémona de mar "verde/rosa", Anthopleura elegantissima, escondida bajo algas rojas, Rhodymenia pacifica en mi acuario.

Micro beasties

I bought myself another microscope. A cheap one, for students, with low magnification, but like the even cheaper one I'd had a few years back (that didn't last long), with the ability to take photos. The one I had been using up to now was for my eyes only.

Tonight, I set it up and collected some stuff from my aquarium; a teaspoonful of sand, a fragment of seaweed, a few empty (or so I thought) shells, and one of the smaller hermit crabs. Arranged them on plastic lids, since they needed to be kept in water, shoved them under the 'scope, and tried to focus. It's a bit difficult when your target keeps running away; even the seaweed was carrying mini-critters on the move.

Pacific rose seaweed, Rhodymenia pacifica. With worm and snails.

This delicate (but oh, so durable in my tank) seaweed is a sheet with one layer of cells. Here, each cell is visible. The fragment was about 3 mm wide. The worm, that looked like a hair, but crawled about slowly, is about as wide as one seaweed cell. Even through the microscope, I didn't recognize the dark patches, but once I blew up the photo, I see that they're all snail shape. No wonder I always have a batch of new tiny snails climbing the walls!

Another snail. Shell only, abandoned in the sand.

This was in the teaspoon of sand. The snail shell is about as large as the larger sand grains. Still tiny. With everything under a film of water, the microscope LED lights produce glitter. I edited out what I could without destroying what is underneath, but the tiniest white specks are moving critters, all constantly in random motion, sort of like a swarm of midges. Some of the brighter patches of light were pulsating, squirming something-or-others. I managed to see a couple of worms and something with legs before they hid under the sand grains again. Some of the sand grains were bouncing; there was something busy underneath.

On an old cluster of empty barnacle shells, a colony of orange-striped green anemones has settled in.

One of my smaller hermit crabs.

I've been wanting to get a good look at these hermits for a while. They look like hairies (Pagurus hirsutiusculus), but never seem to grow up to the expected size. Maybe I'm not giving them enough time. This one certainly looks like a hairy; banded green antennae, blue marks on the legs. But those two rows of lumps on the pincer arm look interesting: I'll have to examine more of these little guys.

A couple of periwinkles.

And a tiny snail, half the size of the smallest periwinkle, on the move. With sand grains for size.

This is fun! Let it rain!

Chiton lips

"Woody", the green and blue chiton in my aquarium, spends most of his time plastered to a shell, a slow-moving, flattish, 2-inch-long mound blending into the background. If he has a "face", it's hidden. But for a moment, the other day, I caught him lifting the edge of his girdle, tasting the water.

Underside of the girdle, and the mouth, open. Also present: an amphipod, a mud snail, and a pink-tipped green anemone.

Woody does not have a head, as we understand the term. He has no eyes, tentacles, or brain here, just the mouth. (His shell does include light-sensitive spots, but around his mouth, there is no need, since it is usually clamped tight against the substrate.)

Like many other molluscs, chitons feed with a thin strap bearing rows of teeth known as the radula. The anterior rows are used up and discarded or swallowed and replaced by new rows moving forward like a conveyor belt. ... The chiton radula is noteworthy because one pair of cusps in each row is hardened with magnetite, which provides these teeth with a coating harder than stainless steel. They are the only molluscs that have magnetite-coated teeth. In fact, they are the only organisms known to manufacture such vast quantities of magnetite. (http://biology.fullerton.edu/deernisse/pubs/Eernisse_07_chitons_Tidepools.pdf)

Before I start to take photos through the glass, I scrub the inside walls; overnight, they develop a coating of green algae. A soft cloth removes most of it, but underneath that, there's always a more tenacious growth of yellowish-brown algae; for that, I use a green kitchen scouring pad, scrubbing and wiping with the cloth alternately. With a fingernail, I pry off harder lumps.

And even then, once I give up, the glass is still covered with these tiny pink dots, visible against the yellow flesh of the chiton. Pacific rose seaweed, trying to establish itself on every surface in the aquarium. When it grows on a shell, I can't rip or scrape it all off; it's tremendously tenacious. I tear off and discard double handfuls every time I clean the tank, but the glued-on "roots" are always left behind, ready to leap into action.

So fragile-looking, so delicate! And so strong!

Pacific rose

Delicate blades of red algae:

Pacific rose seaweed, Rhodymenia pacifica

This seaweed, common enough among the scraps tossed up on the shore by the tides, but usually out-competed in the intertidal zone by the sea lettuces and rockweed, is the only one that loves its home in my tank. Other seaweeds float around, sometimes for a couple of weeks, until the hermits and crabs have worn them to shreds. Eelgrass holds out a bit longer, but eventually turns black and disintegrates, leaving only the roots.

Rose seaweed grows and grows and grows. I rip out handfuls every time I clean the tank. But it's a popular hangout; the handfuls always come with a crowd of amphipods, a couple of hermit crabs, and maybe a snail or two. I have to wash them out carefully and return them to the tank.

So I always leave a small clump, usually attached to a rock. And a few days later, it's grown and taken over half the tank. I think it likes it here.