The Blue Groper fish have a unique way to control their population: they can change their sex!
Bob Harcourt, Associate Professor Macquarie University: "The blue groper is a large fish, but the really sexy thing about Blue Groper is they start off as females. We've got lots of blue groper that are small green groper and as an old male dies then the largest most dominant females turns blue and becomes male.
And so one of the really cool things about these fish, is the sex ratio doesn't really vary, but it is a function of how well protected they are. If you take a lot of males out, then the females have to spend a lot of their time turning into males, which means they can't breed and they can't lay eggs."
Now, the blue groper may be in danger. Their population has crashed and scientists are trying to figure out why. National Geographic has the video clip: Link - Thanks Marilyn!
But for the benefit of the others who be less informed, isn't the fish really called a GROUPER and not a GROPER? I've seen a couple on several dives already but never have I been cupped for a feel on the family jewels...
I wish I could remember which fish (I want to say chichlid)only has one fertile male in a group that's a more vivid color than the rest. When the fertile male goes missing, a sterile male (not sure how it knows it's the next up) starts to change color after a few days and becomes fertile after a few more.
And those monstery looking anglerfish that live so deep that they never see any light? In some of the species, it's so hard to find a mate that when a male (tiny in comparison to the female) finds a female, he latches on with his teeth until becoming partially absorbed--an appendage--like a little sperm factory that she can seemingly control along with her reproductive cycle to release sperm when needed. Researchers didn't know there WAS a male at all for years, he was unrecognizable as a separate fish.
Reproduction is pretty complex for a lot of species, like bees and wasps. We get used to thinking of gender and reproduction in mammalian terms. It gets tough to imagine things like this (and stranger) exist in nature. I find it all fascinating. I wish more people knew about all the variety out there, it seems like it might make people more open minded.