A study by Simon Oliver at the School of Ocean Sciences, Bangor University describes the first observations of thresher sharks venturing into shallow coastal waters to interact with cleaner wrasse, a type of small fish that groom other fish species.

Thresher sharks live in the open oceans and much of the knowledge of them to date is based on fisheries bycatch. This study just published in published in PLoS ONE, (14 March 2011) examined the behaviour of these elusive sharks as they invite cleaners to remove parasites and dead tissue.

The sharks and cleaning stations are vulnerable to dynamite fishing on the shallow reefs, and the cooperative interaction between the species is disturbed by human activities.

Adapted behaviour

The researchers demonstrated that sharks regularly visit ‘stations’ where they adapt their behaviour to facilitate cleaning services by ‘posing’ and making themselves more attractive for cleaner fishes. Cleaners then choose to feed on specific parasites from specific areas of the shark’s body.

The study highlights key ecological links between the effects of parasite infection on sharks and the necessity for their control through services provided by ‘cleaners’ who remove them.