In the Journal of Molluscan Studies, there’s an article about the penis of a species of squid, Onykia ingens. It’s, um, long. Like, as long as the entire animal. Why so long? Shallow water cephalopods have short penises but use an arm to hand the sperm over to the females, but the deep sea squids prefer to inject the sperm directly. No one had figured out exactly how this occured until a recently caught squid obliged researchers by unfurling himself. Read more about it on BBC news.