Meeting Abstract

P1.161  Saturday, Jan. 4 15:30  Developmental changes in the escape response of California halibut JIMENEZ, Y/E*; MACDONALD, I/A; DICKSON, K; GIBB, A/C; Northern Arizona University; Northern Arizona University; California State University Fullerton; Northern Arizona University yej2@nau.edu

Flatfishes (Pleuronectiformes) are symmetrical as larvae and become asymmetrical when they settle out of the water column and become benthic adults. These life history changes in morphology and orientation relative to the environment may necessitate changes in locomotor behaviors. We examined videos of California halibut escape responses for pre-metamorphic, metamorphic, and juvenile individuals and identified four escape response behaviors. These were designated as C-starts, S-starts, O-starts, or J-starts, according to the shape of the body during the first phase of the escape behavior. Pre-metamorphic larvae frequently performed S-starts and produced more C-starts as they grew older. J- and O-starts were only observed in older individuals and occurred infrequently. Relative escape velocities (TL/s) generated by S, C, and J-starts were similar, but O-starts were approximately two times slower. Pre-metamorphic larvae tended to escape towards left-hand side of the body, while metamorphic and juvenile halibut always escaped towards the eyed side. Despite having a 1:1 ratio of right-handed to left-handed individuals as adults, larval halibut may be “hardwired” evolutionarily to escape toward the left-hand side, which may be an evolutionary “artifact” because the family (Paralichthyidae) is predominantly left-handed. Additional work will be necessary to determine how the different movement patterns exhibited by California halibut across development allow the animals to interact with the specific features of their environment (the sounding fluid, substrate, etc.) to produce an effective movement to evade predators.