by Padre Art

Created on: December 13, 2008   Last Updated: February 01, 2009

" The barnacle is a shrimp-like animal standing on its head in a limestone house and kicking food into its mouth with its feet.", according to Louis Agassiz, the Swiss-American naturalist, succinctly summing up a few of the interesting facts about barnacles.

Barnacles were thought to be mollusks until 1830 when their larval stage was discovered. This fact landed them squarely into Arthropoda, crustacea, cirripedia. Most of the actual scientific research on barnacles was done by none other than Charles Darwin. Spending the better part of the decade after returning from his voyage on the Beagle in the meticulous study and classification of both living and fossil specimen, the process required him to restructure the entire classification field which had been in considerable disarray until that time, and then publishing this exhaustive treatise in the mid 1800's.

There are, in general, two types of this sessile hermaphrodite. The first is the gooseneck barnacle, having a calcareous shell attached to a base such as a rock, a piece of wood, metal, or even some other marine creature by a stalk that is leathery on the outside but very edible on the inside. The gooseneck barnacle may be steamed (over wine and herbs), boiled, grilled, or served in broth, soup, or chowder. Do be careful when peeling the stalk, the liquid may stain.

The second type of barnacle is the acorn barnacle, which is a rounded hexagon of six plates attached at the wider base to a rock, dock, or other object and that narrows to the apex in a volcanic sort of way having another two plates to close up the top, when necessary, or open to allow the six pairs of legs to extend out with the elegant, feathery plumes that are characteristic of their "feet".

There are some barnacles that are mobile even though they are permanently attached to a base. That base just happens to be a porpoise, turtle, or even a gooseneck barnacle that grows on an acorn barnacle that grows on a whale. Another mobile member of the family is the parasitic Sacculina barnacle that attaches to a crab through a seam or joint in the crabs shell. At this point it sends out tendrils throughout the crabs body, not killing it but making it infertile and changing its behavior. When another Sacculina joins the first after being alerted by secretions from the established parasite the two mate and lay millions of eggs in the host crab which lives and is manipulated to tend the larva of the barnacles. The alterations are made at such a basic

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