The diversity of evolution: it's downright amazing, and we're not just talkin' wings and eyeballs- we're talkin' animal penises! Trace takes us on a tour of the animal kingdom's boxer shorts.I already wrote about barnacles in Barnacles show that "nature finds a way", but I just happen to have an article about another example from Matt Kaplan in Nature who wrote Sea slug loses penis after sex but grows another the next day.
Invertebrate may discard organ like a dirty needle to avoid carrying competitors' sperm.What do you expect from someone who wrote his Ph.D. dissertation about self-fertilization in snails?
The astounding warning colours of the nudibranchs, a diverse group of sea slugs, are certainly enough to attract attention — but even they pale in comparison to the gripping news that one species of the soft-bodied molluscs has a habit of discarding its penis.
Nudibranchs are hermaphrodites, meaning that they carry both male and female reproductive organs. Moreover, when they mate, they can perform the male role of donating sperm and the female role of receiving sperm at the same time. This process involves two penises and two vagina-like organs, and sperm transmission effectively happens simultaneously during the encounter.
This is a relatively standard arrangement among nudibranchs, so the creatures' sexual organs might all be expected to look roughly the same. But the animals show incredible sex-organ diversity, and it was during an exploration of this diversity in the species Chromodoris reticulata that researchers made their jaw-dropping discovery.