Friends with benefits - Cleaning symbiosis

Have you ever wondered why so many animals live in perfect harmony with each other?

Sometimes it is because they can rely on each other for resources. Although the majority of symbiotic interactions occur at the microscopic level (Gilbert et al. 2015), there are symbiotic relationships that we can appreciate without the microscope. Some of the best known examples of these relationships are cleaning symbiosis where one species will pick the parasites off another for food. This is particularly common in birds and fish for example, the cattle and egret commensalism.

Cattle egrets Bubulcus ibis with a cow (Dupont 2016)

The cattle egret Bubulcus ibis is known to live among various animals such as deer and cattle to pick off and eat parasites such as ticks that may live on them (Palmer et al. 2019; Chaskda et al. 2018). Although Egrets are not obligatory symbionts, Chaskda et al. 2018 found that egrets that feed of flock parasites do spend less time looking for food than egrets that do not feed off cattle even when there is an abundance of insects. These types of commensalisms have been documented between various birds, mammals and reptiles (Chaskda et al. 2019).

Fish are friends, not food.

  

Cleaning symbiosis is also common in fish such as Wrasse & Gobies that feed off parasites from other often predatory fish. Many fish species in the family Labridae have a evolved dark dorsal stripe indicative of their cleaning status. Scientists believe that this may help cleaning fish advertise their cleaning status to other fish (Arnal et al. 2006). Another study found that the cleaning fish with a bright blue band were more successful in attracting fish to be cleaned (Cheney et al. 2009). Some species also oscillate to advertise their services to fish (Gingins et al.2017). However, there are some fish that have cheated the system.

A White Spotted Pufferfish Arothron hispidus being cleaned by a Hawiian Wrasse Labroides phthirophagus (Inaglory 2010)

Too much of a good thing?

Cleaning mutualisms can sometimes turn into parasitism in the right circumstances.  Some cleaning fish will try to eat some of their hosts instead of the parasites. As a result the client fish will chase the cleaners to threaten them or swap partners (Gingins et al.2017). 

A new discovery 

A recent study found a possible mutualism for the first time between white tailed deer Odocoileus virginianus, insectivorous bats & parasitic horse flies Tabanidae where bats were seen eating the flies (Palmer et al. 2019). This is one the first documented symbiotic relationships with detached parasites an opens the door for the possibility of exploring cleaning symbiosis between bats and other animals.

For more animal examples go here: https://galapagosconservation.org.uk/symbiotic-relationships-galapagos/

Thanks for reading J

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