Sunday, April 08, 2018

Barnacle spirit

You never know what to expect in a tank full of critters. I was watching barnacles catching dinner, when one, or rather its ghost, came out into the open.

Thatched acorn barnacle. In life, the cirri are black.

It swayed in the current for a few minutes, then the rest of the body bubbled out.

The long, thick appendage is the barnacle's penis. When the barnacle is searching for a mate, it extends to 8 times the body length. An obvious solution to the problem of being glued in place.

Soon, the entire body floated free. Before a hermit or crab caught it, I fished it out and photographed it on a wet black background.

The long cirri (feathery tentacles) are the legs the barnacle fishes with. I'm not sure of the function of those shorter feathers. Near the base of the penis, the ridging is visible. Muscle tissue, maybe?

Another view, showing the entire body. The head end is on the left; in life, it stays cemented to the floor of the barnacle casing.


  1. Amazing photograph of something that in the ocean would last mere seconds before disappearing into the flotsam.

  2. I was lucky to be sitting with my nose to the aquarium at the right moment.


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