Behavioral responses to sound stimuli in cuttlefish (Sepia officinalis)

Sound is an important sensory cue for many marine animals that use acoustics for mate attraction, habitat identification and predator avoidance. Cephalopod sound detection abilities were suggested over a century ago and have been a subject of debate since. Yet there are few data addressing potential behavioral responses of cephalopods to sound, their sensitivity range, or whether sound plays a functional ecological role. This study examined the behavioral responses of 12 cuttlefish (Sepia officinalis) to tone pips ranging from 80 1000 Hz and intensities of 110 165 dB re 1 ¼Pa. The most dramatic responses (jetting and inking) were observed for sounds between 100 and 200 Hz and at 300 Hz (juveniles only), all at intensities above 140 dB re 1 ¼Pa. Subtle skin patterning changes and fin movements were observed at all frequencies and intensities. Similarly to vertebrates, cephalopods showed a decrease in reaction latency when the sound intensity increased, suggesting an energy-based detector. Potential habituation to sound stimuli was examined using repeated (n=45) presentations at 200 Hz and two sound intensities. A decrease in response intensity was observed, especially in younger animals, supporting behavioral adaptation and some habituation. However, response extinction was not reached. The gradation in behavioral responses, habituation and reaction times to acoustic stimuli have not yet been described for marine invertebrates and strongly suggest a functional use to sound detection in cuttlefish and other cephalopods.