As my Senior Thesis at Amherst College, I studied the mating system of the gulf pipefish Syngnathus scovelli. The abstract of my thesis is below. If you are interested in reading more, you can download the entire thesis from the link.
The relationship between sex roles, sex ratios, and sexual dimorphisms in the mating system of the gulf pipefish, Syngnathus scovelli.
This study was the first to use the gulf pipefish, Syngnathus scovelli, as an experimental animal in a laboratory setting. As such, it establishes guidelines for the husbandry of the species. I found the gulf pipefish to be a sex role reversed species, where females competed more intensely than did males for access to mates because males limited female reproductive success. As a result, females were more aggressive than males and possessed extensive secondary sexual characteristics (ornaments), which were used in intrasexual competition and during courtship. The ornaments were found to be reliable indicators of fitness because starved or sick individuals could not express them. This study also provides supporting evidence that the extent of sex role reversal and mating system of the gulf pipefish is highly dependant on the operational sex ratio, the ratio of sexually mature females to sexually mature males. I observed significant differences between the levels of aggression displayed by both males and females in male- and female-biased tanks, showing the importance of environmental factors on the behaviors of a species. In addition, both females and males were able to mate with multiple partners under certain conditions. Therefore, I classified the gulf pipefish as polygynandrous, contrary to previous studies.