Starter cities in pink and cream

On a blade of old eelgrass, the hermits and snails and the sea urchin were busy. Watching them, I noticed specks on the eelgrass, pink and cream.

Two bryozoan colonies, and social tunicate starter homes.

The bryozoans were mostly eaten by the time I found them. Now, a couple of days later, there's not a trace of them. The hermits tear down their walls and eat the animals inside.

They won't eat the social ascidians, but the sea urchin will, so today most of the pink spots were gone.

10 years ago (how time flies!) I wrote about the social tunicates in my tank, probably the same species as this crop. They are a colonial animal; one settles in and buds off new individuals (zooids), arranged in a double row around an open centre, with a circle of blood vessels around the outside of the colony.

Zooming in on the lower group. Just a baby colony.

I looked at a few of these under my microscope.

Here you can see the central siphons of some of the zooids.

10 years ago, there was no sea urchin in my tank. The hermits left the tunicates, on sea lettuce, strictly alone, and the colonies grew. And grew.

Photo from 2010; two colonies, yellow and pink.

There's more information about the structure and lifestyle of these animals in that post. And if these survive the onslaught of a hungry, growing urchin, I'll try to get clearer photos.

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En una hoja de hierba Zostera en mi acuario, mientras observaba a los ermitaños y caracoles y el erizo de mar que allí buscaban su cena, vi unas manchas de color crema, y otras color de rosa. Las de color crema eran briozoos, ya casi todos muertos. Los ermitaños les rompen las paredes y comen los zooides que viven adentro. Ahora, unos dias más tarde, no queda ni un vestigio de las colonias.

Las manchitas de color de rosa son ascidios coloniales. Estos, se los come el erizo de mar, así que ahora solo hay unos puntitos de colonias nuevas.

 Hace diez años, crecieron unas colonias de urocordados, en mi tanque. No había quien las comiera, y llegaron a cubrir una gran cantidad de lechuga de mar. Escribí sobre ellos, describiendo su estructura y manera de vida, en aquel entonces. Aquí está el post.

Son animalitos que viven en colonia, aunque pueden sobrevivir y empezar nuevas colonias si quedan aislados. Uno se fija en su sitio, y empieza a brotar clones, arreglados en una fila doble con un espacio en el centro, y un círculo de venitas alrededor. En la foto que saqué con el microscopio se pueden ver, apenas, las bocas centrales de cada zooide.

La última foto es una que saqué de las colonias grandes hace diez años. Aquí se ven claramente los sifones de cada animal.

Si es que el erizo no se las come todas, trataré de sacar fotos más claras.

Lifer! Probably for both of us.

Under the logs and lumber of any floating construction, down where the sun rarely reaches, the water level is constant, the currents weakened, myriads of animals and plants live their sheltered lives, away from the prying eyes of the humans who clomp along overhead. Unless there is a gap between the floats, the surface is mometarily still, the light turns down at the perfect angle, and a human just chances to look down that gap at that moment. And then, if the human happens to be of a curious bent, she flops down on her knees or belly, and peers down that gap. And sees eyes, staring back at her.

Spiny pink scallop, Chlamys hastata. She has dozens of eyes, lined up along her lips. She can't see as well as I do; all she saw of me (I think) was my shadow.

Another angle, showing a bit of her shell, and two anemones sheltering underneath. The blue "pillar" is a mussel shell.

I'll back off a bit, to show the mini underwater garden along the base of the float I was lying on.

Tunicates, purple stuff, more tunicates, mystery critters, worms, and hydroids. Yesterday's anemones were just to the left of this patch.

Moving to the right; more tunicates, and the scallop.

I cropped these photos down, to show the individual critters a bit better:

Tunicates, unidentified. (With intake, outflow siphons circled.)

As far as I can tell, the pale cyan blobs have siphons, as well, and would be another species of tunicate (aka sea squirt). The red line in the centre points to another animal that is so transparent that its internal organs, and its food are visible through the wall. I think the other red line points to a half-way shut down anemone. On the far left, there is a hydroid stalk, and on the left of the base of the big tunicates, the flowery shape is the feeding tentacles of a worm.

Tunicates, tunicates, worms, etc. And what are those two potato-like blobs?

And there's still that pink thingie:

I think it may be a compound ascidian. like the red ascidian, or maybe the mushroom compound tunicate. Or something else? What do you think?

Worms tomorrow.