This is a quickie to share something randomly fascinating, courtesy of Schnakenberg et al. (2011). Their study looked at the effect of killing a certain cell type in the sperm storage organs of female fruit flies. They mainly looked at the effect of this on things like, well, sperm storage, sperm behaviour, number of eggs the females laid.
Experimental flies weren’t as good at laying eggs as normal females, and the reason for this is the really interesting bit. The eggs were fully formed and by all accounts, normal – they just got stuck inside the mother. And kept developing, to the point where the researchers could coax nearly-hatched eggs with wriggling maggots inside from the females.
I can’t go all “ha! this is how live birth evolves!” at creationists, since none of these maggots were actually born without the experimenters messing with their mothers. Still, that’s the sort of surprise I would like to see when I do creepy things to innocent little animals!
Schnakenberg SL, Matias WR, Siegal ML (2011) Sperm-storage defects and live birth in Drosophila females lacking spermathecal secretory cells. PLoS Biol 9:e1001192.