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Journal of Experimental Biology partnership with Dryad

Sound production in red-bellied piranhas (Pygocentrus nattereri, Kner): an acoustical, behavioural and morphofunctional study
Sandie Millot, Pierre Vandewalle, Eric Parmentier
  1. Fig. 1.

    Velocity of swimbladder wall displacement (twitch): A corresponds to the start of the movement, B to the maximal velocity and the half of swimbladder displacement, C to maximal velocity through the return of the swimbladder to its resting position, and D to the end of the movement. The A–B segment represents the velocity increase that corresponds to the main peak sound energy, and the C–D segment represents the recovery phase.

  2. Fig. 2.

    Oscillograms and sonograms of recorded sounds in Pygocentrus nattereri. (A) Sound type 1, or bark (1, initial; 2, main; 3, terminative sequence of sound); (B) sound type 2 (black arrow indicates the first part of the sound); (C) sound type 3. The dotted lines indicate the beginning and the end of each sound.

  3. Fig. 3.

    Maximum displacement (A–B; see Fig. 1) amplitude of cranial (black) and caudal (white) swimbladder sac at different sonic muscle stimulation rates. NS, not significant difference; *, significant differences (P<0.05) between swimbladder sacs (factorial ANOVA, Newman and Keuls test).

  4. Fig. 4.

    Oscillograms of cranial swimbladder movement for a sonic muscle stimulation at 20 Hz (A), 100 Hz (B) and 150 Hz (C).

  5. Fig. 5.

    Oscillogram of cranial swimbladder movement at 100 Hz. The arrow corresponds to the end of sonic muscle stimulation.

  6. Fig. 6.

    Amplitude of cranial swimbladder displacement (squares), peak amplitude variability (triangles) and recovery time (circles) for each sonic muscle stimulation rate.