Thursday, January 28, 2016

Unexpected guests

I was hunting for barnacles. My leafy hornmouth snails were hungry, and that's all they would eat. And I wasn't having any luck. I walked miles down the shore, over several days, finding nothing. Not a barnacle in sight, except on huge rocks. At the higher tide levels, they don't like small stones that can be rolled around by the waves, crushing their shells. For critters with only feet and an intestine, they're remarkably smart.

Last Saturday, I was out searching again. Nothing, nothing, nothing. I gave up and started walking at the extreme high tide line, where seaweeds and bits of driftwood tossed up by the recent stormy weather were drying. And there, far above their normal haunts, I found three large oysters, covered in barnacles.

They had to be dead by now, cast up this far above the usual water line for several days. But the barnacles would be ok, and I could open up the oysters, scrape them out, and put the clean shells with their load of snail food into the tank. I brought them home.

Except that they weren't dead. When I put them in water to wash them off, they opened up. When I touched them, they closed down. Alive and healthy; they're hardier than I imagined.

Oysters in the aquarium. With happy leafy hornmouth snails and hermits.

The snails got busy right away, eating several big barnacles each every day. And the scavengers, hermits and crabs, swarmed over the shells, picking away all the rotting seaweed, cleaning out dying barnacles. (The snails won't touch those: they like their meals very fresh.) The oysters pumped water in and out as the hermits cleaned off their lips.

Under the detritus, the hermits discovered a couple of anemones, looking miserable, shut down and fraying. The hermits took over, tearing away all the dead flesh, cleaning out the wounds. A day later, the anemones were as good as new.

Anemone # 2. Looking good. Smaller than a barnacle. Pink-tipped anemone, Anthopleura elegantissima, maybe.

Yesterday's anemone, once the minor surgery was finished, went for a walk and ended up parked on one of the snails. In the top photo, above, it's on the snail on the right.

While I was at it, I took a few more photos of the warty tunicate (the orange tubes in front of the oysters above). It has also been thoroughly cleaned by the hermits; they're busy little beasties.

Warty tunicate, Pyura haustor, showing the "warts", now that the old gunk is gone.

Zooming in on one siphon. It looks like a smaller tunicate is growing there.


  1. What a wonderful ecosystem - except for when one eats the other, they seem to help each other.

  2. Cooperation is what keeps the system running.

  3. What an interesting addition to our tank, and actions by your snails and hermits to bring the anemones back to health. - Margy

  4. Facinating post, Susannah! Once my mother wrote a children's book about a Seri indian girl lost in the desert near the ocean (unpublished book). She wanted to see how long the girl could carry clams with her and keep them alive ... wrapped up in a bundle of seaweed. They were good for 5 days. It would be interesting to know just how long your oysters were up on the beach.
    I loved hearing how the hermit crabs went to work.


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