Life on Australian Seashores, Marine Education Society of Australiasia (MESA)
"Barnacles are most unusual animals. They are arthropods, in the same major group as insects and spiders, and are most closely related to decapod crabs, prawns, lobsters and yabbies.
"Unlike most of their relations, barnacles are usually fixed to a rocky surface. The larvae go through several distinct swimming stages as plankton, before settling into place onto a rock. The juveniles pick their place to settle because they can detect their adults by chemical means...."
The page is a pretty good introduction to barnacles, with links to related pages on the website and a list of books 'for further reading.' This is definitely a page created as an educational tool, by dedicated academicians. Kudos, for keeping a fairly easy-to-read style - and useful illustrations.
One thing you won't find in the diagram of an adult barnacle's anatomy is a nervous system. There's a reason for that: Although barnacles have a central nervous system, it degenerates a bit when they settle down as adults.
I think most of us have known people like that: folks who dropped into a familiar routine after their teens, and don't seem to have done much with their brains after that.
Never could see the appeal in that sort of life, myself: but then, one of my favorite quotes is "There is no such thing on earth as an uninteresting subject; the only thing that can exist is an uninterested person." (G. K. Chesterton, The Quotations Page - quoted May 31, 2009 in this blog)
More, decidedly not light reading, about barnacle brains:
- "Neurophylogeny: Architecture of the nervous system and a fresh view on arthropod phyologeny"
Integrative and Comparative Biology, Life Sciences, Oxford Journals (Volume 46, Number 2)