Like platypus, echidnas lay eggs and produce milk. Now, new research published in the journal Sexual Development sheds light on another spectacular adaptation of this unusual animal: Short-beaked echidnas, Tachyglossus aculeatus , possess a four-prong penis.
Each rosette-shaped glans contains a urethra; that is , each of the four tips is capable of releasing sperm and urine, but surprisingly only two of them are used to reproduce.
Lead researcher Jane Fenelon believes this is because the mass of spongy tissue that surrounds the male urethra is completely separated from the rest of the echidna penis. In the same way, the penile artery divides into two branches in the echidna penis, which would explain why only two glans manage to ejaculate and how this adaptation of unilateral ejaculation is made possible.
Monotremes, the order of mammals that include echidnas (and platypus), diverged about 184 million years ago, which could explain why they share some of their traits with unrelated animals.
Perhaps the role that this four-pointed penis plays indicates that there is a possibility of showing that males also have a reptilian remnant in their evolutionary development. At the moment, the researchers plan to continue delving into how this unusual structure develops and what its role is in the evolutionary puzzle of these animals.
Referencia: The Unique Penile Morphology of the Short-Beaked Echidna, Tachyglossus aculeatus Fenelon J.C.a · McElrea C.a · Shaw G.a · Evans A.R.b · Pyne M.c · Johnston S.D.d · Renfree M.B.a Sexual Development DOI : https://doi.org/10.1159/000515145
