A tasty orange

Last week's storms had tossed up many sponges with the torn seaweeds. Some were shredded, dead, sun-bleached, white, as I usually find them after a windstorm. But this week, most were still bright orange.

Orange finger sponge, Isodictya rigida, as found. On a bed of shredded rockweed, sea lettuce, turkish towel, and eelgrass.

I brought home a couple of pieces, one white, one still orange, and put them in the aquarium to see what my critters thought of them.

Orange (and white) finger sponge. With crab hiding underneath, hermit climbing in back.

The hermits climbed the white specimen, taking a few nibbles, then went back to eating the kelp stipe I'd brought them.

The larger crab (seen beneath the orange sponge) ripped big chunks off the orange sponge and ate them; an orange powder floated off into the water as he ate. That was in the first hour; after that, he and the other crabs went back to eating kelp. They've ignored both pieces of sponge ever since, and the orange piece is retaining its colour. I wonder if it's still alive; how can you tell, with sponges?

Central Coast Biodiversity says that dorid nudibranchs and blood stars eat this sponge. It looks like crabs are not so inclined. My little sea urchin has not made a move in its direction, either.

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Las olas y el viento habían aventado muchas esponjas, despegadas de su sitio en el fondo, hacia la playa, donde, arrastradas por el viento, terminaron en la parte superior de la playa, entre montones de hierbas y algas marinas hechas trozos. Algunas de las esponjas eran como las encuentro comunmente, rotas, blancas, blandas, muertas. Pero muchas eran nuevas, con su color fuerte anaranjado sin disminuir.

Me traje dos pedazos, uno anaranjado, el otro blanco, a casa para ver que hacían mis animales con ellos, y los coloqué en el acuario.

Allí, los ermitaños se treparon al pedazo blanco, tomando una u otra mordida, después regresando al kelp que también les había traído; allí se han quedado, comiendo kelp.

El cangrejo grande (que en la foto se ve escondido debajo de la esponja) arrancó grandes pedazos de la esponja grande, y se los comió; la esponja emitió un polvo amarillo mientras el cangrejo comía. Esto al principio, pero pronto perdió interés y se fue con los otros cangrejos a comer kelp. Desde entonces, los dos pedazos de esponja se mantienen sin cambio. (¿Estará viva la esponja amarilla? ¿Cómo se puede saber, con las esponjas, que son enteramente pasivas?

Central Coast Biodiversity dice que los nudibranquios y algunas estrellas de mar, (las estrellas sangrientas) comen estas esponjas. Parece que los cangrejos y ermitaños no cuentan entre sus predadores. Y mi pequeño erizo de mar no se ha acercado, tampoco.

Orange sponge

If I could dive, I would. Beyond my reach, even at the lowest of low tides, the sea floor is a treasure house of amazing animals and plants. But I'm limited to shallow waters and tide pools.

And then again, there are those high, really high tides. And winter storms. And the waves bring me what I could never reach on my own.

I found another large sponge on the shore at Oyster Bay. This one is the largest I've seen yet, around 9 or 10 inches across, measured by my 7-inch finger span. And it was as yet partially unbleached by sun and sand.

One specimen, white where the light had hit it, orange where it was protected by seaweeds. On the red inner bark of an alder.

I have posted photos of these before, here and here. The larger was 7 inches across, and had been tossed in the sand until it was completely filled. I have it at home now, and after drying and shaking and shaking and banging about, it is still grey with sand. And the bit of orange colour on the underside has completely disappeared.

As far as I can see, it looks like the Orange Finger sponge, Neoesperiopsis rigida. These, according to my guide and a couple of websites, grow to 25 cm. (10 inches) tall. This one is a bit smaller, bottom to top.

I left this one on the shore near where I found it. My hands were already full of plastic pieces I was removing; I'd forgotten to bring a bag. I did bring home a large kelp holdfast, still fresh, for my hermit crabs. They've been working on it ever since, night and day.

Sand trap

Another find on the same flat beach:

Unidentified sponge, as found at the top of the intertidal zone.

At home, dried and cleaned up. Sand still fills many of the pores. 7 inches diameter.

The sponge had evidently been ripped out of its home and tossed up by the waves. It was still damp, and on the underside, where the sunshine didn't reach, it was orange. The green spots seem to be the green algae that grows on everything. Once the sponge was dry, the orange colour disappeared.

Sponges are difficult to identify, especially out of context. (The Encyclopedia lists 26 undetermined sponges after their photos of named species.) I think this may possibly be an Orange Finger sponge, Neoesperiopsis rigida, a sponge I remember seeing on the underside of a local dock. They may be quite varied in shape and colour: INaturalist has a series of photos demonstrating this: pale orange, pink, brownish, but not green; long and skinny, or in rounded clumps.

A sponge is an animal that is basically a filtration device. The "fingers" are hollow; water flows in through the porous walls and is pumped out through the larger upper opening. Food particles, tiny plankton, shreds of organic material, get filtered out along the way.

A closer look at some of the "fingers".