Subterranean Fishes of the World

3249

2017

AIM 2017

Bilaterians organisms are, in fact, not completely bilateral. There are morphological asymmetries in many animals, with some notorious examples in fishes; like Perissodus microlepis with scaleeating morphs with a jaw bended to the left (or to the right) that eats scales of other fishes’ right flank (or left flank) or like flounder fishes with both eyes located at the same side of the head. It has been described that Astyanax mexicanus cavefishes possess different craniofacial arrangements at the right side of the head, such as extensive fragmentation or fusion in suborbital bones, compared with the left side. Asymmetry of behavior or preference for the left or right side, reflects partitioning of information processing in either hemisphere of the brain and is a common feature in land and aquatic animals including fishes. Visual stimuli and response play an important role in “Handedness”, therefore it will be interesting to explore if lateral dominance (either right or left) exist in blind Cavefish Astyanax morphs adapted to perpetual darkness. In behavioral experiments, we explored the lateral preference of Astyanax mexicanus cavefishes (CF) or surface fishes (SF) to navigate a maze in search for food. In experiments, carried out in complete darkness (recorded with infrared cameras) using wild caught fish, we found that SF prefer to solve the maze using the right side, while CF do not seem to show a clear preference for either side. SF trained to use the right door keep using the right door when presented with both choices, however when SF trained to use the left door were presented with both options, the majority will switch to use the right door. Further studies will be performed to understand the environmental influence on lateral preference and the importance of the visual function for handedness.

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