What does it take for animals to survive in the wild? The most obvious factors that come to mind include being able to forage or hunt, while successfully evading predators. A critical factor we often forget to think about, perhaps due to its seemingly subtle and less exciting nature, is the ability of wild animals to stay clean. Some of the most fascinating interactions and behaviours to behold in the wild are not always the sensational hunting sequences, animals devouring their kill, or their elaborate mating rituals. It is the extent to which some animals will go to maintain good hygiene. This is especially fascinating, and easy to observe in the ocean where animals of all sizes come together in the quest to be and help others be disease-free.
Parasites latch onto fish of all sizes, getting between their scales, gills, and other soft tissue. They steadily drain their hosts’ resources and increase their chances of contracting diseases. Parasites can literally weigh their hosts down. Some of the most unlikely examples of cooperation between species in the ocean have evolved to address this threat to an animal’s fitness.
“Cleaning symbiosis” is a fascinating, mutually beneficial therapeutic exchange between animals that want parasites removed from their bodies, and animals that feed on those parasites for a living. Humans are not the only ones to understand the value of “spa treatments”; fish and aquatic invertebrates also partake in the stress-relief and hygienic benefits of being cleaned and massaged, often by unrelated species. Cleaners like cleaner wrasses and cleaner shrimps offer these fish (their clients) the service of carefully getting rid of their parasites, nipping them in the bud. A win-win situation to all parties involved in the cutthroat race for survival.