Platypus fact of the day: genes and girly parts

part one of a new daily feature

Humans, of course, have two pairs of sex chromosomes: XX or XY. The noble platypus has five pairs (ie, a male platypus is XYXYXYXYXY, while a female platypus is XXXXXXXXXX). However, being the platypus, their chromosomal system is weird, and may or may not be more similar to the ZW system, found mostly in birds, where the female has a 'Z' and 'W' chromosome and the male has two 'Z's.

We do not know how those chromosomes functionally turn your little embryonic 'pus into a male or female. Pretty much all other mammals have a gene called SRY, which codes for a certain protein that makes boys into girls: everyone starts out female, in a sense, but if you have that Y chromosome, SRY starts being produced. Unless you're a platypus, in which case you lack the SRY gene, and we haven't a clue how it works.

But if you do turn out to be a girl platypus, congratulations! You're a girl! You have...well, an ovary and a half, really. Technically, you have two, but unlike even your few fellow egg-laying mammals, only your left one ever fully develops. Why? Because you're a platypus, that's why. You also get two uteruses, though presumably, the right one is pretty much useless.

You produce milk, like all other mammals, but unlike most of them you lack teats. Instead, you have pores on your abdomen which you secrete milk from, and it pools in little grooves in your skin, so your little one can lap it up.

And if you're a very nice platypus, someday genetic research on you, you lovable weirdo, may save some human ovaries.