Friday, December 13, 2013

No end to mysteries

There's always something new . . .

I keep trying to get a decent photo of a limpet with its mouth open, scraping algae. This was better than most; the radula inside the mouth is visible, and even some of the internal organs show dimly through the meat of the foot. But what is that other tube around its "neck"?

1/4 inch long limpet, cleaning the aquarium wall.

I've spent several hours looking at limpet photos and reading anatomy pages. Nothing resembles that yellow tube that snakes out from the left side of the mantle and reaches out to the surrounding water. One source ( mentions that keyhole limpets often carry a commensal scaleworm in the mantle groove. But this isn't a keyhole limpet, and that's no scaleworm.

Could it be a ribbon worm?

Any ideas?


  1. My first thought was a parasite of some kind, but couldn't guess what it might be. - Margy

  2. Can't remember if limpets have the same anatomy as the slipper-shell snails I studied (Crepidula spp.), but they do look quite similar; if so, that may well be a penis.

  3. Olivia, I hadn't thought of that. I've spent every spare minute today searching for info about either penises or commensals in these limpets.

    The slipper snail has a penis, but the true limpets do not.
    "At the posterior ventral end is the large gonad organ which, when ripe, bursts and empties its contents into the right kidney from which they are expelled directly into the surrounding water" (Wikipedia)

    Also, "As the common limpet has no penis or uterus, it is necessary to examine the internal sex-organ (the gonad) to determine the sex." (Nature)

    But it seems that a variety of worms live in limpet shells. I didn't find any mention specifically of our shield limpet, Lottia pelta, though.


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