Barnacles...what exactly are they...

…do they only grow on whales and ships?

And how can they form on something that would seem to spend most of its time moving? Why don’t they ‘wash off’ when they swim.
I have a feeling that there is an extreamly easy answer to this…(But I’ll kick myself in the butt later. =)

Thanks guys and gals!

They’re crustaceans. As larva, they resemble shrimp. When they mature, they glue themselves onto a surface and catch food with their feet. Their glue is extremely strong, which is why they don’t come off easy.

http://www.umassd.edu/public/people/kamaral/thesis/Barnacles.html

is a good basic site.

Barnacles evolved to survive in turbulent waters; that’s how they catch food. When food-laden water moves past the barnacle, it reaches out of its little shell-like home and grabs it. They actually are able to reach more food by attaching themselves to moving objects, like whales or ships. As andygirl noted, they attach themselves to said surface with a natural adhesive that’s about the stregth of Krazy Glue. I’m sure Chief Scott or some other sea-going doper could tell you how hard it is to remove the little bastards once they’ve become attached to a ship’s hull.

Hooray! Barnacles! Interesting critters.

How can one not admire these things? Armored hermaphrodites with penises longer than they are tall, and yet they only love the girl next door.

They also attach themselves to rocks, bulkheads, bridges and just about anything they darn well please. There can be some very strong and regular current at these structures due to tides, making it an ideal breading ground for the little buggers