Résumé
The behavioural aspects discussed in this Chapter are not unique to marine parasites. Parasites do change the behaviour of their hosts in all environments, and cleaning symbiosis is widespread on land and in fresh water. The ability of some parasites to drastically change a host's behaviour, often leading to behaviour patterns favouring the parasite and ensuring its transmission to other hosts, has been known for some time. It is a fascinating area of research that deserves much greater attention in future work. As pointed out by the authors of this section, numerous examples of host manipulation by parasites remain to be discovered, but the examples already known show that manipulation has the potential to interfere with ecological and evolutionary processes. Research in this area may resolve important issues relating to ecosystem functioning and biodiversity.
With regard to cleaning symbiosis, various birds pick off parasites from terrestrial mammals, and there are many freshwater cleaning fish. However, cleaning symbiosis has been best studied in the sea. Reasons are that diversity of cleaning associations that can easily be observed is greatest in the ocean and particularly in tropical seas; and that scuba diving, the method most widely used for studying cleaning behaviour, is best suited to clear subtropical and tropical marine waters. Numerous postgraduate students have, therefore, become involved in these studies, leading to a vast literature on cleaning symbiosis, which is very competently reviewed in this Chapter. This section not only discusses current knowledge but also points the way to future studies.