Soc for experimental Biol Annual Meeting - Salzburg 2012

Paolo Domenici (CNR IAMC, Italy), Tommy Norin (Arhus University,
Denmark), Peter G. Bushnell (I ndiana University South Bend, Indiana,
USA), Jacob Johansen (James Cook University, Australia), Peter
Skov (DTU Aqua, Technical University of Denmark, Denmark), John F.
Steffensen (University of Copenhagen, Denmark), Morten Svendsen
(Technical University of Denmark, Denmark) and Augusto Abe
(Unlversidade Estadual Paulista, Brazil)

Fast starts are brief accelerations commonly observed in fish within the
context of predator-prey interactions. In typical C-start escape responses.
fish react to a threatening stimulus by bending their body into a C-shape.
Recently, similar C-starts have been recorded in archerfish stimulated by
the fall of a prey item on the water surface, and in tapping motions of
goldfish, a behaviour that was interpreted to be food-related.
Little is known about C-starts being used outside the context of
escaping or feeding. Here, we test the hypothesis that air-breathing
fish may use C-starts when gulping air at the surface. Air breathing is
a common behaviour in many fish species when exposed to hypoxia,
although certain species perform air-breathing in normoxia to fill their
swim bladders for buoyancy control and/or sound transduction.
Hoplos/emum littorale is an air-breathing freshwater catfish found in
South America. Field video observations reveal that their air-breathing
behaviour consists of a fast air-gulping motion at the surface, followed by
swimming towards the bottom. Using high-speed video in the laboratory,
we compared the kinematics of spontaneous air-gulping performed by
H. littorale in normoxia. with those of mechanically-triggered C-start
escape responses. Our results show that these two behaviours overlap
considerably in their kinematics (turning rates and distance covered),
suggesting that air breathing in this species is performed using escapelike
C-start motions. This demonstrates that C-starts in fish do not need
external stimulation and can be spontaneous behaviours used outside the
context of predator-prey interactions.
Email addressforcorrespondence:paolo.domenici@cnr.it