The behavioural role of pit organs in the epaulette shark
Epaulette sharks Hemiscyllium ocellatum in three treatments, pit organs (free neuromasts) ablated, sham-operated and normal (n = 8 for each treatment), showed a significant preference for facing upstream in a flume (P < 0·05). There were no significant differences in the mean angles or angular variances among treatments. Individuals with ablated pit organs, however, spent significantly less time moving around than controls (P < 0·05), suggesting that pit organs contributed to motivation for activity. Pit organs do not appear to make an important contribution to rheotaxis in H. ocellatum. It is suggested that this may be due to structural differences in the pit organs of H. ocellatum compared with other species.