Differences in running velocity and boldness between male and female Atlantic sand fiddler crab (Leptuca pugilator)

Abstract

Atlantic sand fiddler crabs (Leptuca pugilator) exhibit an extreme case of sexual dimorphism with the male crabs wielding an enlarged dominate claw that can account up to 40% of an individual’s total body mass. The salt pans found in marine marshes are commonly colonized by fiddler crabs and have limited coverage from avian predators, making the ability to quickly run back their burrows, an important part of life. After threats have passed, making the decision of when to exit is important for securing resources and finding a mate, but if done too early could mean falling victim to a predator. This study pairs experiments and observations to determine if crab anatomy or personality is more important influence on running velocity and boldness. Crabs (21 males & 21 females) were ran and timed on a sand racetrack for 1m, behavior assays were conducted to determine each individuals boldness, and measurements of various anatomical measurements were taken. Female crabs were found to have faster run velocities than male crabs. However, male crabs displayed bolder behavior than female crabs. Overall, personality was found to be the most important factor on a crab’s running velocity and boldness.