![]() But this is the first time this has been seen in a mammal, so we really don't know.” Most of the time the four-tipped wonder is tucked away. They may also be able to alternate which epididymis the sperm come from each time. “In the one male echidna we have erection details for, he alternates the use of each side each time which suggests the potential for a quick turnaround. “It's possible it's to do with male-male competition for females,” explained Fenelon. Four tips in a penis that can essentially switch sides per mating event is all well and good, but how does it help these prickly bachelors? ![]() This combined with the penile artery which is split into two branches in the echidna penis explains why only two tips turn up to the party, and how this unilateral ejaculation adaptation is made possible. Before the study we predicted there was going to be some sort of valve mechanism that controlled this, but we found nothing like that.” The males can flit from one side to the next quite quickly, potentially increasing their reproductive opportunities. “Together with the split of the major blood vessel and urethra it gives the impression that the end of the echidna penis is acting like two separate glans penises, which explains how they could do the unilateral ejaculation. “In most other species these start separate but then they merge,” Fenelon told IFLScience. Lead author and research fellow Dr Jane Fenelon believes this is due to the corpora spongiosa, the mass of spongy tissue that surrounds the males’ urethras, being entirely separate from the rest of the echidnas' penis. ![]() ![]() Each of the four tips is capable of delivering sperm as well as urine, but remarkably only two of them are used per reproductive attempt. ![]()
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