Slacker Wrap-Up Part I: Eau de Toilette (Literally)
I will try to redeem myself—slowly. I have a whole slew (like five) of completely researched and partially written posts. After careful deliberation, I’ve decided that three of them are keepers. I’ve also decided that if I haven’t gotten around to writing full posts on any of these enthralling topics, I never will. Instead, I hope to lure you back to our blog with three post-ettes.
Eau de Toilette (Literally)
Peeing on mates isn’t all that unique (porcupines do it), but it’s certainly noteworthy—especially in an aquatic environment (a.k.a. a giant toilet).
In two no-longer-recent studies, scientists examined the uri-sexual behaviors of two aquatic organisms. In the first species, the sheepshead swordtail (Xiphophorus birchmanni), the male does the noteworthy peeing. In something known as the “audience effect,” these males pee more in the presence of female sheepshead swordtails than when they are alone.
The authors explain the noteworthiness of this behavior here:
“In order to minimize fluid loss, terrestrial animals must concentrate urine and release it in specific times and places. This basic physiological constraint has facilitated the evolution of spatiotemporal control of chemical signaling in terrestrial taxa. Relatively free of this constraint, however, freshwater organisms urinate more or less continuously. Thus, the remarkable degree of control over the release of chemical signals by male swordtails is likely the result of intense selective pressures on males to transfer important information directly to potential mates.”
Translation: Bladder control is essential for terrestrial animals, but freshwater animals essentially live in their toilet, giving them the luxury of being able to pee non-stop, whenever and wherever they want. The male sheepshead swordtail is therefore a remarkable creature simply because it is potty-trained (with the area surrounding female sheepshead swordtails functioning as the potty).
The second noteworthy pee-er is the female signal crayfish (Pacifastacus leniusculus). Male and female signal crayfish play very different roles in child-rearing (males are deadbeats while females provide sole parental care for six months) and approach mating accordingly (males are sluts, females are selective).
When signal crayfish pee, they release aggressive signals that other signal crayfish interpret as something like ‘I’m gonna f**k you up, biotch’. The female crayfish means it, but when a male gets her message he stops peeing because, well, he thinks her challenge is pretty hot. The two fight and while they fight, the female assesses her challenger. If he’s tough enough to thwart her resistance, they mate.
Berry, F., & Breithaupt, T. (2010). To signal or not to signal? Chemical communication by urine-borne signals mirrors sexual conflict in crayfish BMC Biology, 8 (1) DOI: 10.1186/1741-7007-8-25
Rosenthal, G., Fitzsimmons, J., Woods, K., Gerlach, G., & Fisher, H. (2011). Tactical Release of a Sexually-Selected Pheromone in a Swordtail Fish PLoS ONE, 6 (2) DOI: 10.1371/journal.pone.0016994