[Forrest Travirca]

Forrest Travirca asked the Naked Scientists:
   
How long does it take a submerged object before it becomes a suitebale host for barnacles?

What do you think?

[Oceans Helen]

It probably depends on a range of factors including whether there happens to be a cloud of barnacle larvae wafting past and if the surface has any anti fouling chemicals on it to keep larvae away - and a big factor is whether or not barnacles are already present...

The weirdest fact about barnacles is that they have the longest penis (relative to body size) of any animal - yup - a vital tool since adults stick themselves firmly in place and need to reach across to other individuals to mate successfully.

So... having a long penis is all very well, but it means that barnacle larvae still need to settle down fairly close to other barnacles (no point being a lone barnacle all on your own - there's only so far your penis can stretch). And a few years ago, researchers at the Universities of Plymouth and Newcastle figured that barnacle larvae detect a specific chemical in the exoskeleton of adult barnacles that guides them to settle close where there are other barnacles.

But, the question is, how does the first barnacle decide to colonise a new surface when there aren't already adults there?