![Australian researchers discover why only two of echidna's four penis heads become erect at one time | Australia news | The Guardian Australian researchers discover why only two of echidna's four penis heads become erect at one time | Australia news | The Guardian](https://i.guim.co.uk/img/media/3559d0d68afaf94e75bf51143509274fefffafc5/0_138_4372_2622/master/4372.jpg?width=465&quality=85&dpr=1&s=none)
Australian researchers discover why only two of echidna's four penis heads become erect at one time | Australia news | The Guardian
![Lindsey Wakefield on Twitter: "@arvalis This makes perfect sense. It reminds me of what one of my friends said regarding cats. In order to draw a sitting cat, just draw a penis Lindsey Wakefield on Twitter: "@arvalis This makes perfect sense. It reminds me of what one of my friends said regarding cats. In order to draw a sitting cat, just draw a penis](https://pbs.twimg.com/media/FUQfR31WYAA9HXB.jpg)
Lindsey Wakefield on Twitter: "@arvalis This makes perfect sense. It reminds me of what one of my friends said regarding cats. In order to draw a sitting cat, just draw a penis
![Australian researchers discover why only two of echidna's four penis heads become erect at one time | Australia news | The Guardian Australian researchers discover why only two of echidna's four penis heads become erect at one time | Australia news | The Guardian](https://i.guim.co.uk/img/media/d3fadd01edc9b19f597c1f7d3638581ac85ee822/0_108_1440_864/master/1440.jpg?width=445&quality=85&dpr=1&s=none)