as I mentioned earlier I think it is a male only display organ. Many organisms develop structures that would be wasteful because they display how effective a male is at surviving. look at deer. the largest species grew antlers so large it couldn't even enter dense woodlands or else it would get tangled, look at the vibrant colours a variaty of male birds, reptiles, and fish develop that make them stand out like a sore thumb to predators. heck wild guppies will even play chicken with each other in front of predators to attract mates. These structures and behaviours make males seem ridiculous and suicidal to us but make females want to mate with that particular male.