29 December 2011

When barnacles were mollusks

This brightly colored picture of the gooseneck barnacle (Lepas anatifera) is from Edward Donovan's The Natural History of British Shells published in 1799.

Back then, and until the 1830s, barnacles were grouped together with mollusks, simply because they had shells as do most frequently encountered mollusks. Barnacles are actually arthropods, because they have jointed appendages like insects and their relatives. This post was about a barnacle on a snail shell.

Here is the title page of Donovan's book. It is available on Google Books.


Anonymous said...

The larger shelly plates in the gooseneck barnacle, once they are separated and are clean and loose, well they do look superficially rather like the valves of a bivalve. I had a hard time persuading a friend of mine who found some in the beach drift on Nevis that they were not bivalve shells at all but part of a barnacle. I don't think he believed me.


Susan J. Hewitt

Anonymous said...

Umm random offtopic question (I lost the related blog post where I saw three Deroceras slugs sleeping together under a rock): do you happen to know why Deroceras slugs would attack each other? I know they eat their dead but the few I picked up from outside start biting each other if they get close. Smaller slugs are clearly distressed by this and escape. I'm asking because I'd like to put them all in a bigger snailery I have but I'm afraid they will kill each other! I give them protein-rich food in the form of tortoise food so that need should be satisfied. They are also not bothered by bigger snails, Helix aspersa, that I have in my snailery. Just others of the same species.