Hung Like a Barnacle

By Chris Doyle on May 17, 2012 in Other

Birds do it. Bees do it. Even barnacles do it.

Yes, even barnacles have sex. If you thought living your life with your head glued to a rock would limit your sexual prowess, think again.

Barnacles can be found on coastal rock platforms and on floating objects such as buoys, driftwood, boats and even whales. Looking like little volcanoes, barnacles are crustaceans, just like prawns and crabs, but with their body encased by a series of hard, interlocking plates. At low tide, barnacles appear lifeless. However, when submerged by the tide, they extend their limbs out into the current and trap particles of food.

Barnacles begin life floating around in the ocean as larvae until they settle onto an object or rock, cement themselves to it head first and then undergo metamorphosis to end up looking the way we usually see them.

But if you are going to have sex, you need a mate, right? And just how do you go about finding a mate when you have cemented yourself to a rock? By having the longest penis in the world is how, relative to body size of course.

The barnacle penis can reach up to eight times the length of its own body, making barnacles the most well endowed animal we know. During mating, the barnacle unfurls its long penis and casts it out into the ocean in search of a female that is willing to mate. The penis is covered in sensory bristles that allow the barnacle to detect willing females. When it finds one, the barnacle will insert its penis into the female’s casing and fertilise her eggs. But don’t think he will be the only one doing so – barnacles can be quite promiscuous and up to six males have been observed simultaneously copulating with a single female.

Length is not the only thing going for the barnacle penis. The thickness of the penis is very important and varies depending on where a particular barnacles lives. Barnacles living in areas exposed to waves grow thicker penises than those that live in sheltered areas. This provides them with more support so that they are less likely to flail about in the surf and also reduces the chance of them breaking off in the rougher conditions.

Before you go telling your mates that you are hung like a barnacle, bear in mind that barnacles are actually hermaphrodites – they have both male and female reproductive parts. So a barnacle that is throwing its penis around now may in fact enjoy being on the receiving end of one a few hours later. Also, being so well endowed uses up a lot of unnecessary energy when the penis is not being used, so barnacles can discard their penises at the end of the mating season and not regrow another one until the next mating season comes around. So unless you like spending a good part of the year without your penis, being hung like a barnacle may not necessarily be considered a very attractive feature.

Several species of barnacle can be found on rock platforms right across the Eastern Beaches, but unless you are an extremely patient snorkeller or diver, you are not likely to catch a glimpse of barnacle sex in the wild. There are, however, numerous videos of barnacles doing their thing on the Internet, so check them out there. And the next time you see a cluster of barnacles on a rock platform, take a closer look at the distance between them to appreciate yet another natural wonder that is sharing this beautiful part of the world with you.