Editing Symbiosis (section)

== Types ==

=== Obligate versus facultative ===

Relationships can be obligate, meaning that one or both of the symbionts entirely depend on each other for survival. For example, in [[lichen]]s, which consist of fungal and [[photosynthetic]] symbionts, the fungal partners cannot live on their own.<ref name="Wilkinson-2001"/><ref>{{Harvnb|Isaac|1992|p=266}}</ref><ref>{{Harvnb|Saffo|1993}}</ref><ref name="Douglas-2010-2">{{harvnb|Douglas|2010|p=4}}</ref> The algal or cyanobacterial symbionts in lichens, such as ''[[Trentepohlia (alga)|Trentepohlia]]'', can generally live independently, and their part of the relationship is therefore described as facultative (optional), or non-obligate.<ref name="Muggia-2013">{{cite journal |last1=Muggia |first1=Lucia |last2=Vancurova |first2=Lucie |last3=Škaloud |first3=Pavel |last4=Peksa |first4=Ondrej |last5=Wedin |first5=Mats |last6=Grube |first6=Martin  |title=The symbiotic playground of lichen thalli--a highly flexible photobiont association in rock-inhabiting lichens |journal=FEMS Microbiology Ecology |volume=85 |issue=2 |pages=313–323 |date=August 2013 |pmid=23530593 |doi=10.1111/1574-6941.12120 |bibcode=2013FEMME..85..313M |doi-access=free }}</ref> When one of the participants in a symbiotic relationship is capable of photosynthesis, as with lichens, it is called photosymbiosis.<ref>{{cite web |title=photosymbiosis |website=Oxford Reference |url=https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100324758;jsessionid=FFCC5585B976D5CF87DDD905A035A006 }}</ref><ref>{{cite journal |last1=Gault |first1=Jordan A. |last2=Bentlage |first2=Bastian |last3=Huang |first3=Danwei |last4=Kerr |first4=Alexander M. |title=Lineage-specific variation in the evolutionary stability of coral photosymbiosis |journal=Science Advances |date=2021 |volume=7 |issue=39 |pages=eabh4243 |doi=10.1126/sciadv.abh4243 |pmid=34550731 |pmc=8457658 |bibcode=2021SciA....7.4243G }}</ref>

=== Ectosymbiosis versus endosymbiosis ===

[[File:An alder root nodule gall.JPG|thumb|Alder tree root nodule houses endosymbiotic [[nitrogen-fixing bacteria]].]]

{{Main|Ectosymbiosis}}{{Further|Endosymbiont}}

[[Ectosymbiosis]] is any symbiotic relationship in which the symbiont lives on the body surface of the [[Host (biology)|host]], including the inner surface of the [[digestion|digestive]] tract or the ducts of [[exocrine gland]]s.<ref name="Paracer-2000-2"/><ref>{{Harvnb|Nardon|Charles|2001}}</ref> Examples of this include [[ectoparasites]] such as [[lice]]; [[commensalism|commensal]] ectosymbionts such as the [[barnacles]], which attach themselves to the jaw of [[baleen whales]]; and mutualist ectosymbionts such as [[cleaner fish]].<!--REWRITE-->

Contrastingly, [[endosymbiosis]] is any symbiotic relationship in which one symbiont lives within the tissues of the other, either within the cells or extracellularly.<ref name="Paracer-2000-2" /><ref>{{Harvnb|Sapp|1994|p=142}}</ref> Examples include diverse [[microbiome]]s: [[rhizobia]], [[nitrogen-fixing bacteria]] that live in [[root nodules]] on [[legume]] roots; [[actinomycete]]s, nitrogen-fixing bacteria such as ''[[Frankia]]'', which live in [[alder]] root nodules; single-celled [[algae]] inside reef-building [[coral]]s; and bacterial [[endosymbiont]]s that provide essential nutrients to about 10%–15% of insects.<ref>{{Cite journal |last1=Mus |first1=Florence |last2=Crook |first2=Matthew B. |last3=Garcia |first3=Kevin |last4=Garcia Costas |first4=Amaya |last5=Geddes |first5=Barney A. |last6=Kouri |first6=Evangelia D. |last7=Paramasivan |first7=Ponraj |last8=Ryu |first8=Min-Hyung |last9=Oldroyd |first9=Giles E. D. |last10=Poole |first10=Philip S. |last11=Udvardi |first11=Michael K. |last12=Voigt |first12=Christopher A. |last13=Ané |first13=Jean-Michel |last14=Peters |first14=John W. |date=1 July 2016 |editor-last=Kelly |editor-first=R. M. |title=Symbiotic Nitrogen Fixation and the Challenges to Its Extension to Nonlegumes |journal=Applied and Environmental Microbiology |volume=82 |issue=13 |pages=3698–3710 |doi=10.1128/AEM.01055-16 |pmc=4907175 |pmid=27084023 |bibcode=2016ApEnM..82.3698M }}</ref>

In endosymbiosis, the host cell lacks some of the nutrients which the [[endosymbiont]] provides. As a result, the host favors endosymbiont's growth processes within itself by producing some specialized cells. These cells affect the genetic composition of the host in order to regulate the increasing population of the endosymbionts and ensure that these genetic changes are passed onto the offspring via [[Vertical transmission (symbiont)|vertical transmission]] ([[heredity]]).<ref>{{cite book |last1=Latorre |first1=A. |author2=Durban, A. |author3=Moya, A. |author4=Pereto, J. |title=The role of symbiosis in eukaryotic evolution. Origins and evolution of life – An astrobiological perspective |year=2011 |pages=326–339 }}</ref>

As the endosymbiont adapts to the host's lifestyle, the endosymbiont changes dramatically. There is a drastic reduction in its [[genome]] size, as many genes are lost during the process of [[metabolism]], and [[DNA]] repair and recombination, while important genes participating in the DNA-to-RNA [[Transcription (genetics)|transcription]], protein [[Translation (biology)|translation]] and DNA/RNA replication are retained. The decrease in genome size is due to loss of protein coding genes and not due to lessening of inter-genic regions or [[open reading frame]] (ORF) size. Species that are naturally evolving and contain reduced sizes of genes can be accounted for an increased number of noticeable differences between them, thereby leading to changes in their evolutionary rates. When endosymbiotic bacteria related with insects are passed on to the offspring strictly via vertical genetic transmission, intracellular bacteria go across many hurdles during the process, resulting in the decrease in effective population sizes, as compared to the free-living bacteria. The incapability of the endosymbiotic bacteria to reinstate their wild type [[phenotype]] via a recombination process is called ''[[Muller's ratchet]]'' phenomenon. Muller's ratchet phenomenon, together with less effective population sizes, leads to an accretion of deleterious [[mutation]]s in the non-essential genes of the intracellular bacteria.<ref>{{cite journal |last=Moran |first=N. A. |title=Accelerated evolution and Muller's rachet in endosymbiotic bacteria |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=93 |issue=7 |pages=2873–2878 |date=April 1996 |pmid=8610134 |pmc=39726 |doi=10.1073/pnas.93.7.2873 |doi-access=free |bibcode=1996PNAS...93.2873M }}</ref> This can be due to lack of [[Selection (biology)|selection]] mechanisms prevailing in the relatively "rich" host environment.<ref>{{cite journal |last1=Andersson |first1=Siv G.E |author2-link=Charles Kurland |last2=Kurland |first2=Charles G. |title=Reductive evolution of resident genomes |journal=Trends in Microbiology |volume=6 |issue=7 |pages=263–268 |date=July 1998 |pmid=9717214 |doi=10.1016/S0966-842X(98)01312-2 |author1-link=Siv G. E. Andersson }}</ref><ref>{{cite journal |last=Wernegreen |first=J.J. |title=Genome evolution in bacterial endosymbionts of insects |journal=Nature Reviews. Genetics |volume=3 |issue=11 |pages=850–861 |date=November 2002 |pmid=12415315 |doi=10.1038/nrg931 }}</ref>

=== Competition ===

{{main|Competition (biology)}}

Competition can be defined as an interaction between [[organism]]s or species, in which the [[fitness (biology)|fitness]] of one is lowered by the presence of another.<ref>{{Cite web |title=Species Interactions and Competition |url=https://www.nature.com/scitable/knowledge/library/species-interactions-and-competition-102131429/ |access-date=5 February 2023 |website=Nature}}</ref> Competition can also occur between cells within the same organism which is why older cells are usually eliminated from tissues. This allows the organism to stay as healthy as possible by constantly eliminating old cells and making new ones.<ref>{{Cite journal |last1=Maruyama |first1=Takeshi |last2=Fujita |first2=Yasuyuki |date=2022-02-01 |title=Cell competition in vertebrates — a key machinery for tissue homeostasis |url=https://www.sciencedirect.com/science/article/abs/pii/S0959437X21001180 |journal=Current Opinion in Genetics & Development |volume=72 |pages=15–21 |doi=10.1016/j.gde.2021.09.006 |pmid=34634592 |issn=0959-437X}}</ref> [[Limiting factor|Limited]] supply of at least one resource (such as [[food]], [[water]], and [[territory (animal)|territory]]) used by both usually facilitates this type of interaction, although the competition can also be for other resources.<ref name="Begon-1996">Begon, M.; Harper, J.L.; Townsend, C.R. 1996. ''Ecology: individuals, populations, and communities'', Third Edition. Blackwell, Cambridge, Massachusetts. Chapters 5 "Intraspecific Competition" and 8 "Interspecific Competition"</ref>

=== Amensalism ===

[[File:Black Walnut middle.JPG|right|thumb|The [[black walnut]] secretes a chemical from its roots that harms neighboring plants, an example of [[antagonism (phytopathology)|antagonism]].]]

Amensalism is a non-symbiotic, asymmetric interaction where one species is harmed or killed by the other, and one is unaffected by the other.<ref>Toepfer, G. "Amensalism". In: ''BioConcepts''. [http://www.biological-concepts.com/views/search.php?term=1440 link] {{Webarchive|url=https://web.archive.org/web/20171209043914/http://www.biological-concepts.com/views/search.php?term=1440 |date=2017-12-09 }}.</ref><ref name="Willey-2013">{{cite book |last1=Willey |first1=Joanne M. |last2=Sherwood |first2=Linda M. |last3=Woolverton |first3=Cristopher J. |year=2013 |title=Prescott's Microbiology |edition=9th |pages=713–738 |isbn=978-0-07-751066-4}}</ref> There are two types of amensalism, competition and [[antagonism (phytopathology)|antagonism]] (or antibiosis). Competition is where a larger or stronger organism deprives a smaller or weaker one of a resource. Antagonism occurs when one organism is damaged or killed by another through a chemical secretion. An example of competition is a sapling growing under the shadow of a mature tree. The mature tree can rob the [[sapling]] of necessary sunlight and, if the mature tree is very large, it can take up rainwater and deplete soil nutrients. Throughout the process, the mature tree is unaffected by the sapling. Indeed, if the sapling dies, the mature tree gains nutrients from the decaying sapling. An example of antagonism is ''[[Juglans nigra]]'' (black walnut), secreting [[juglone]], a substance which destroys many herbaceous plants within its root zone.<ref>''Encyclopædia Britannica''. "[http://www.britannica.com/EBchecked/topic/19211/amensalism Amensalism (biology)]". Retrieved September 30, 2014.</ref>

The term ''amensalism'' is often used to describe strongly asymmetrical competitive interactions, such as between the [[Spanish Ibex|Spanish ibex]] and [[weevil]]s of the genus ''[[Timarcha]]'' which feed upon the same type of shrub. Whilst the presence of the weevil has almost no influence on food availability, the presence of ibex has an enormous detrimental effect on weevil numbers, as they consume significant quantities of plant matter and incidentally ingest the weevils upon it.<ref name="Gómez-2002">{{cite journal |last1=Gómez |first1=José M. |last2=González-Megías |first2=Adela |year=2002 |title=Asymmetrical interactions between ungulates and phytophagous insects: Being different matters |journal=Ecology |volume=83 |issue=1 |pages=203–11 |doi=10.1890/0012-9658(2002)083[0203:AIBUAP]2.0.CO;2}}</ref>

=== Commensalism ===

{{main|Commensalism}}

[[File:Fly June 2008-2.jpg|right|140px|thumb|[[Commensalism|Commensal]] mites travelling ([[phoresy]]) on a fly (''[[Pseudolynchia canariensis]]'')]]

Commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped. It is derived from the English word [[wikt:commensal|commensal]], used of human [[social interaction]]. It derives from a medieval Latin word meaning sharing food, formed from ''com-'' (with) and ''mensa'' (table).<ref name="Paracer-2000"/><ref>{{Harvnb|Nair|2005}}</ref>

Commensal relationships may involve one organism using another for transportation ([[phoresy]]) or for housing ([[inquilinism]]), or it may also involve one organism using something another created, after its death ([[metabiosis]]). Examples of metabiosis are [[hermit crab]]s using [[gastropod]] shells to protect their bodies, and spiders building their webs on [[plants]].

=== Mutualism ===

{{main|Mutualism (biology)}}

[[File:Calcinus laevimanus hermit crab with Calliactis sea anemone. 2 frames in one.jpg|thumb|upright=1.25|[[Hermit crab]], ''Calcinus laevimanus'', with sea anemone]]

Mutualism or interspecies [[reciprocal altruism]] is a long-term relationship between individuals of different [[species]] where both individuals benefit.<ref name="Paracer-2000">{{Harvnb|Paracer|Ahmadjian|2000|p=6}}</ref> Mutualistic relationships may be either obligate for both species, obligate for one but facultative for the other, or facultative for both.

[[File:Bryolith (Banc d'Arguin, Mauritania).jpg|thumb|upright|[[Bryolith]]s document a mutualistic symbiosis between a [[hermit crab]] and encrusting [[bryozoans]].]]

Many [[herbivores]] have mutualistic [[gut flora]] to help them digest plant matter, which is more difficult to digest than animal prey.<ref name="Moran-2006"/> This gut flora comprises cellulose-digesting [[protozoans]] or bacteria living in the herbivores' intestines.<ref>"symbiosis." The Columbia Encyclopedia. New York: Columbia University Press, 2008. Credo Reference. Web. 17 September 2012.</ref> [[Coral]] reefs result from mutualism between coral organisms and various algae living inside them.<ref>{{Harvnb|Toller|Rowan|Knowlton|2001}}</ref> Most land plants and land ecosystems rely on mutualism between the plants, which [[carbon fixation|fix]] carbon from the air, and [[Mycorrhizal|mycorrhyzal]] fungi, which help in extracting water and minerals from the ground.<ref>{{Harvnb|Harrison|2005}}</ref>

An example of mutualism is the relationship between the [[ocellaris clownfish]] that dwell among the [[tentacle]]s of [[Heteractis magnifica|Ritteri sea anemone]]s. The territorial fish protects the anemone from anemone-eating fish, and in turn, the anemone stinging tentacles protect the clownfish from its [[predator]]s. A special [[mucus]] on the clownfish protects it from the stinging tentacles.<ref>{{Harvnb|Lee|2003}}</ref>

A further example is the [[goby]], a fish which sometimes lives together with a [[Caridea|shrimp]]. The shrimp digs and cleans up a burrow in the sand in which both the shrimp and the goby fish live. The shrimp is almost blind, leaving it vulnerable to predators when outside its burrow. In case of danger, the goby touches the shrimp with its tail to warn it, and both quickly retreat into the burrow.<ref>{{Harvnb|Facey|Helfman|Collette|1997}}</ref> Different species of gobies (''[[Elacatinus]] spp.'') also [[Cleaning symbiosis|clean up ectoparasites]] in other fish, possibly another kind of mutualism.<ref>{{cite journal |last1=Soares |first1=M. C. |last2=Côté |first2=I. M. |last3=Cardoso |first3=S. C. |last4=Bshary |first4=R. |title=The cleaning goby mutualism: a system without punishment, partner switching or tactile stimulation |journal=Journal of Zoology |date=November 2008 |volume=276 |issue=3 |pages=306–312 |doi=10.1111/j.1469-7998.2008.00489.x }}</ref>

A spectacular example of obligate mutualism is the relationship between the [[siboglinid]] [[tube worm (body plan)|tube worm]]s and symbiotic [[bacteria]] that live at [[hydrothermal vents]] and [[cold seep]]s. The worm has no digestive tract and is wholly reliant on its internal symbionts for nutrition. The bacteria oxidize either [[hydrogen sulfide]] or methane, which the host supplies to them. These worms were discovered in the late 1980s at the hydrothermal vents near the Galapagos Islands and have since been found at [[deep-sea]] hydrothermal vents and cold seeps in all of the world's oceans.<ref>{{harvnb|Cordes|Arthur|Shea|Arvidson|2005}}</ref>

Mutualism improves both organism's competitive ability and will outcompete organisms of the same species that lack the symbiont.<ref>{{cite journal |last1=Clay |first1=Keith |last2=Holah |first2=Jenny |title=Fungal Endophyte Symbiosis and Plant Diversity in Successional Fields |journal=Science |date=10 September 1999 |volume=285 |issue=5434 |pages=1742–1744 |doi=10.1126/science.285.5434.1742 |pmid=10481011 }}</ref>

A facultative symbiosis is seen in encrusting [[bryozoans]] and [[hermit crabs]]. The bryozoan colony (''Acanthodesia commensale'') develops a cirumrotatory growth and offers the crab (''Pseudopagurus granulimanus'') a helicospiral-tubular extension of its living chamber that initially was situated within a gastropod shell.<ref>{{cite journal |last1=Klicpera |first1=A. |last2=Taylor |first2=P. D. |last3=Westphal |first3=H. |title=Bryoliths constructed by bryozoans in symbiotic associations with hermit crabs in a tropical heterozoan carbonate system, Golfe d'Arguin, Mauritania |journal=Marine Biodiversity |date=December 2013 |volume=43 |issue=4 |pages=429–444 |doi=10.1007/s12526-013-0173-4 |bibcode=2013MarBd..43..429K }}</ref>

=== Parasitism ===

{{Main|Parasitism}}

[[File:Taenia solium tapeworm scolex with its four suckers and two rows of hooks 5262 lores.jpg|thumb|Head (scolex) of [[tapeworm]] ''[[Taenia solium]]'' is adapted to [[parasitism]] with hooks and suckers to attach to its [[host (biology)|host]].]]

In a parasitic relationship, the parasite benefits while the host is harmed.<ref>{{Harvnb|Paracer|Ahmadjian|2000|p=7}}</ref> Parasitism takes many forms, from [[endoparasites]] that live within the host's body to [[ectoparasites]] and [[parasitic castrator]]s that live on its surface and [[micropredator]]s like mosquitoes that visit intermittently. Parasitism is an extremely successful mode of life; about 40% of all animal species are parasites, and the average mammal species is host to 4 nematodes, 2 cestodes, and 2 trematodes.<ref>{{cite book |last1=Council (US) |first1=National Research |last2=Avise |first2=John C. |last3=Hubbell |first3=Stephen P. |last4=Ayala |first4=Francisco J. |title=In the Light of Evolution: Volume II: Biodiversity and Extinction |date=2008 |publisher=National Academies Press (US) |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK214895/ |chapter=Homage to Linnaeus: How Many Parasites? How Many Hosts? }}</ref>

=== Mimicry ===

{{main|Mimicry}}

Mimicry is a form of symbiosis in which a species adopts distinct characteristics of another species to alter its relationship dynamic with the species being mimicked, to its own advantage. Among the many types of mimicry are Batesian and Müllerian, the first involving one-sided exploitation, the second providing mutual benefit. [[Batesian mimicry]] is an exploitative three-party interaction where one species, the mimic, has evolved to mimic another, the model, to [[deception in animals|deceive]] a third, the dupe. In terms of [[signalling theory]], the mimic and model have evolved to send a signal; the dupe has evolved to receive it from the model. This is to the advantage of the mimic but to the detriment of both the model, whose protective signals are effectively weakened, and of the dupe, which is deprived of an edible prey. For example, a wasp is a strongly defended model, which signals with its conspicuous black and yellow coloration that it is an unprofitable prey to predators such as birds which hunt by sight; many hoverflies are Batesian mimics of wasps, and any bird that avoids these hoverflies is a dupe.<ref name="Vane-Wright-1976">{{cite journal |last1=Vane-Wright |first1=R. I. |year=1976 |title=A unified classification of mimetic resemblances |journal=[[Biological Journal of the Linnean Society]] |volume=8 |pages=25–56 |doi=10.1111/j.1095-8312.1976.tb00240.x}}</ref><ref name="Bates-1861">{{cite journal |last1=Bates |first1=Henry Walter |title=XXXII. Contributions to an Insect Fauna of the Amazon Valley. Lepidoptera: Heliconidae. |journal=Transactions of the Linnean Society of London |date=November 1862 |volume=23 |issue=3 |pages=495–566 |doi=10.1111/j.1096-3642.1860.tb00146.x }}; Reprint: {{cite journal |last1=Bates |first1=Henry Walter |author-link=Henry Walter Bates |year=1981 |title=Contributions to an insect fauna of the Amazon valley (Lepidoptera: Heliconidae) |journal=Biological Journal of the Linnean Society |volume=16 |issue=1 |pages=41–54 |doi=10.1111/j.1095-8312.1981.tb01842.x |doi-access=free }}</ref> In contrast, [[Müllerian mimicry]] is mutually beneficial as all participants are both models and mimics.<ref>{{cite journal |last1=Müller |first1=Fritz |author-link=Fritz Müller |year=1878 |title=Ueber die Vortheile der Mimicry bei Schmetterlingen |journal=Zoologischer Anzeiger |volume=1 |pages=54–55 }}</ref><ref>{{cite journal |last1=Müller |first1=Fritz |author-link=Fritz Müller |year=1879 |title=''Ituna'' and ''Thyridia''; a remarkable case of mimicry in butterflies. (R. Meldola translation) |journal=Proclamations of the Entomological Society of London |volume=1879 |pages=20–29 }}</ref> For example, different species of [[bumblebee]] mimic each other, with similar warning coloration in combinations of black, white, red, and yellow, and all of them benefit from the relationship.<ref name="Mallet-2001">{{cite journal |last=Mallet |first=James |author-link=James Mallet |title=Causes and consequences of a lack of coevolution in Mullerian mimicry |journal=Evolutionary Ecology |date=2001 |volume=13 |issue=7–8 |pages=777–806 |doi=10.1023/a:1011060330515 }}</ref>

=== Cleaning symbiosis ===

{{main|Cleaning symbiosis}}

[[Cleaning symbiosis]] is an association between individuals of two species, where one (the cleaner) removes and eats parasites and other materials from the surface of the other (the client).<ref>{{cite journal |last=Losey |first=G.S. |title=The Ecological Importance of Cleaning Symbiosis |journal=Copeia |volume=1972 |issue=4 |year=1972 |pages=820–833 |doi=10.2307/1442741 |jstor=1442741 }}</ref> It is putatively mutually beneficial, but biologists have long debated whether it is mutual selfishness, or simply exploitative. Cleaning symbiosis is well known among marine fish, where some small species of [[cleaner fish]] &ndash; notably [[wrasse]]s, but also species in other genera &ndash; are specialized to feed almost exclusively by cleaning larger fish and other marine animals.<ref name="Poulin-1996">{{cite journal |last1=Poulin |first1=Robert |last2=Grutter |first2=Alexandra S. |title=Cleaning Symbioses: Proximate and Adaptive Explanations |journal=BioScience |date=1996 |volume=46 |issue=7 |pages=512–517 |doi=10.2307/1312929 |jstor=1312929 }}</ref> In a supreme situation, the host species (fish or marine life) will display itself at a designated station deemed the "cleaning station".<ref>{{Cite journal |last=Losey |first=George S. |date=1972 |title=The Ecological Importance of Cleaning Symbiosis |journal=Copeia |volume=1972 |issue=4 |pages=820–833 |doi=10.2307/1442741 |jstor=1442741 }}</ref> 

Cleaner fish play an essential role in the reduction of parasitism on marine animals. Some shark species participate in cleaning symbiosis, where cleaner fish remove ectoparasites from the body of the shark.<ref name="Keyes-1982">{{Cite journal |last=Keyes |first=Raymond S. |date=1982 |title=Sharks: An Unusual Example of Cleaning Symbiosis |journal=Copeia |volume=1982 |issue=1 |pages=225–227 |doi=10.2307/1444305 |jstor=1444305 }}</ref> A study by Raymond Keyes addresses the atypical behavior of a few shark species when exposed to cleaner fish. In this experiment, cleaner wrasse ''(Labroides dimidiatus)'' and various shark species were placed in a tank together and observed. The different shark species exhibited different responses and behaviors around the wrasse. For example, Atlantic and Pacific lemon sharks consistently react to the wrasse fish in a fascinating way. During the interaction, the shark remains passive and the wrasse swims to it. It begins to scan the shark's body, sometimes stopping to inspect specific areas. Commonly, the wrasse would inspect the gills, labial regions, and skin. When the wrasse makes its way to the mouth of the shark, the shark often ceases breathing for up to two and a half minutes so that the fish is able to scan the mouth. Then, the fish passes further into the mouth to examine the gills, specifically the buccopharyngeal area, which typically holds the most parasites. When the shark begins to close its mouth, the wrasse finishes its examination and goes elsewhere. Male bull sharks exhibit slightly different behavior at cleaning stations: as the shark swims into a colony of wrasse fish, it drastically slows its speed to allow the cleaners to do their job. After approximately one minute, the shark returns to normal swimming speed.<ref name="Keyes-1982"/>