In every way that matters for this book, jacanas are backward. Females are more aggressive than males, they are larger than males, they fight more viciously and frequently than males, and they have larger weapons. Usually it's the other way around. In flies, beetles, mastodons, crabs, and elk, males are armed, not females. Jacanas excepted, in every species with weapons confined to a single sex, males have those weapons. Why should just one sex have weapons? And why is it (almost) always the males?

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 149