Sunday, February 3, 2013
Whoa—put that thing away! What you’re looking at is a gooseneck barnacle (Pollicipes polymerus), a crustacean that grows on rocks and boat hulls. And its penis is sticking out of the top, marked off by an arrow.
For barnacles, this is actually a fairly unimpressive penis. Some species can stretch their penises up to 8-times their body length! (Which, admittedly, is usually pretty small.) They use these long members to physically deposit sperm into the shells of nearby barnacles to reproduce.
But, with such a short penis, how does the gooseneck barnacle reproduce? It is able to spermcast: send its sperm out into the water, which is then collected by other barnacles as it passes over them. It sounds a bit riskier than the long penis method—what if no other barnacles capture your sperm?—but it seems to work pretty well for them.
Read more about the study at Smithsonian Magazine
Image via Barazandeh, et al. Proc. R. Soc. B.