A laboratory study of the behavior of two species of grass shrimp (Palaemonetes pugio Holthuis and Palaemonetes vulgaris Holthuis) and the killifish (Fundulus heteroclitus Linneaus)

In this laboratory study, the frequency of locomotor behaviors for two grass shrimp species, Palaemonetes pugio and Palaemonetes vulgaris, and the killifish Fundulus heteroclitus were determined. Additional behaviors, such as grouping of grass shrimp, and pursuit by killifish, the grass shrimp's common predator, were also analyzed. The results show that mean behavioral frequencies for the two shrimp species were rarely significantly different statistically. Each shrimp species altered its behavior differently in the presence of the other shrimp species, but responded similarly to the presence of the predator. The results indicate that the response of each shrimp species to the predator was dependent upon the predator's size and health. In situations involving the large health predator, both grass shrimp species significantly reduced swimming, but did not show a significant difference in walking. Behavioral frequencies of large and small healthy killifish were not significantly different from each other when alone, but were significantly different in the presence of prey, while the large unhealthy killifish's behavior was significantly decreased in all situations compared to both the large and small health killifish.