Ectoparasite Load Research Articles

No experimental evidence that sibling competition induces young to switch nests in the colonial Alpine swift, Apus melba

Adoption is frequent in colonial animals where opportunities for dependent young to receive care from nonbiological parents are high. The departure of dependent young from their original family to seek adoption in neighbouring families is thought to be induced by sibling competition for access to limited resources provided by poor-quality parents. We tested this hypothesis in the colonial Alpine swift by manipulating the number of young reared per brood, with the prediction that offspring from enlarged broods switch nests more frequently than those from reduced broods. Although nestling swifts hatch with little locomotor activity, from 20 days until their first flight at 50–70 days they frequently move out of their nests to seek adoption in neighbouring families. Although nestlings reared in experimentally enlarged broods were lighter and their body mass at day 20 after hatching was more variable than in nestlings reared in reduced broods, there was no difference between the two treatments in the frequency of nests switching and in the age when nestlings switched nests for the first time. However, consistent with other evidence that nest switching by nestling swifts evolved as a strategy to reduce ectoparasite load, young from broods with naturally high numbers of the ectoparasitic louse fly Crataerina melbae were more prone to switch nests. This shows that ectoparasitism rather than sibling competition is a key proximate factor promoting the evolution of nest switching in the colonial Alpine swift.

Why do males and females of Python regius differ in ectoparasite load?

AbstractA recent study of Python regius from Togo (Aubret et al., 2005) has demonstrated that male pythons suffered for a much higher ectoparasite load than the females. The authors hypothesized that these intersexual differences may depend on increased male movements in the mating season relative to females, thus increasing their chances of meeting with ectoparasites. On the other hand, they suggested that differences in habitat use are unlikely to explain this pattern because males and females are found within the same type of burrows. Based on previously published data on food habits of P. regius in Nigeria, as well as on radiotracking data, I showed that males were more arboreal-dwelling than females. I suggest that ectoparasite load differences between sexes depend on a different use of the space, with males being more arboreal than females, and hence collecting ticks from low tree-branches as well as from the ground levels, whereas the same is less true for the females which are infested mainly by the terrestrial ticks.

Effects of sex and body size on ectoparasite loads in the northern flying squirrel (Glaucomys sabrinus)

Ectoparasites can have profoundly negative fitness consequences for host organisms. Sex differences in parasite load have been documented in many mammals, and have been attributed either to the allocation of energy to growth rather than the immune system in mammals exhibiting male-biased sexual size dimorphism or to the immunosuppressive qualities of testosterone. In addition, ectoparasites can have negative effects on body size and condition, as energy is allocated to the immune system rather than to growth and maintenance. Here, we used the northern flying squirrel (Glaucomys sabrinus (Shaw, 1801)) and its ectoparasites to test two predictions: (1) males are more heavily parasitized than females and (2) individuals with high ectoparasite loads will be in poorer condition and be smaller than individuals with low ectoparasite loads. Males were significantly more parasitized than females, and there was a nonsignificant trend for small males to be more parasitized than large males. Because the northern flying squirrel is not sexually dimorphic, the immunosuppressive qualities of testosterone may explain the sex differences in ectoparasite load. Ectoparasites may also influence skeletal growth rates, and males that are more susceptible to ectoparasites may simply be unable to allocate as much energy to growth and are thus structurally smaller.

Client fish ectoparasite loads and cleaner shrimp Urocaridella sp. c hunger levels affect cleaning behaviour

Cleaning is a classic example of mutualism and determining the factors that maintain the balance between the costs and benefits for mutualist partners can assist our understanding of how cleaning relationships are maintained. Optimal foraging theory suggests two factors that might help to maintain the relationship between cleaners and their clients: client ectoparasite load and cleaner hunger levels. The ecological relevance and importance of foraging by cleaner fish in marine systems has been demonstrated repeatedly, yet there is little information available on this behaviour in cleaner shrimp. To determine whether cleaner shrimp base their choice of client fish on food patch quality (i.e. client fish ectoparasite load) we offered the yellow-beaked cleaner shrimp Urocaridella sp. c a choice of parasitized and unparasitized rock cods, Cephalopholis cyanostigma. To determine whether cleaner shrimp hunger levels influence cleaning time, we manipulated hunger levels in Urocaridella sp. c and examined their behaviour towards parasitized client fish. Cleaner shrimp preferred parasitized to unparasitized client fish and food-deprived cleaner shrimp cleaned parasitized rock cods more frequently than satiated cleaner shrimp did. Therefore, variations in client fish ectoparasite load and cleaner shrimp hunger level are two factors that affect the balance in this mutualism. Finally, our results meet some of the assumptions of biological market theory, a framework used to understand cooperative interactions, and thus this framework is suggested for future studies on this cleaning system.

Female‐biased mortality in experimentally parasitized Alpine SwiftApus melbanestlings

SummarySex‐biased mortality in adult vertebrates is often attributed to lower immunocompetence and higher parasite susceptibility of males. Although sex‐specific mortality has also been reported during growth, the importance of sex‐specific immunocompetence and parasite susceptibility in explaining male‐biased mortality remains ambiguous in growing individuals because of potentially confounding sources of mortality such as sexual dimorphism.Here, we investigated sex‐specific susceptibility to the blood‐sucking louse flyCrataerina melbaeand sex differences in cell‐mediated immunity in a bird species that is sexually monomorphic both in size and plumage coloration at the nestling stage, the Alpine Swift,Apus melba.For this purpose, we manipulated ectoparasite loads by adding or removing flies to randomly chosen nests in two years, and injected nestlings with mitogenic phytohaemagglutinin (PHA) in another year.There were no significant differences between male and female offspring in immune response towards PHA, parasite load, and parasite‐induced decrease in growth rate. Secondary sex ratios were however biased toward males in parasitized broods, and this was explained by a greater mortality of females in parasitized than deparasitized broods.Our findings are in contrast to the widely accepted hypothesis that males suffer a greater cost of parasitism. We discuss alternative hypotheses accounting for female‐specific mortality.

Mutualism or parasitism? The variable outcome of cleaning symbioses

The exact nature of many interspecific interactions remains unclear, with some evidence suggesting mutualism and other evidence pointing to parasitism for the same pair of interacting species. Here, we show spatial variation in the outcome of the cleaning relationship between Caribbean cleaning gobies (Elacatinus evelynae) and longfin damselfish (Stegastes diencaeus) over the distribution range of these species, and link this variation to the availability of ectoparasites. Cleaning interactions at sites with more ectoparasites were characterized by greater reductions in ectoparasite loads on damselfish clients and lower rates of removal of scales and mucus (i.e. cheating) by cleaning gobies, whereas the opposite was observed at sites where ectoparasite abundance was lower. For damselfish clients, cleaning was therefore clearly mutualistic in some locations, but sometimes neutral or even parasitic in others. Seasonal variability in ectoparasite abundance may ensure that locally low parasite availability, which promotes cleanerfish cheating, may be a transient condition at any given site. Conflicting conclusions about the nature of cleaning symbioses may, therefore, be explained by variation in ectoparasite abundance.

Testosterone Inhibits Growth in Juvenile Male Eastern Fence Lizards (Sceloporus undulatus): Implications for Energy Allocation and Sexual Size Dimorphism

In the eastern fence lizard, Sceloporus undulatus, female-larger sexual size dimorphism develops because yearling females grow faster than males before first reproduction. This sexual growth divergence coincides with maturational increases in male aggression, movement, and ventral coloration, all of which are influenced by the sex steroid testosterone (T). These observations suggest that male growth may be constrained by energetic costs of activity and implicate T as a physiological regulator of this potential trade-off. To test this hypothesis, we used surgical castration and subsequent administration of exogenous T to alter the physiological and behavioral phenotypes of field-active males during the period of sexual growth divergence. As predicted, T inhibited male growth, while castration promoted long-term growth. Males treated with T also exhibited increased daily activity period, movement, and home range area. Food consumption did not differ among male treatments or sexes, suggesting that the inhibitory effects of T on growth are mediated by patterns of energy allocation rather than acquisition. On the basis of estimates derived from published data, we conclude that the energetic cost of increased daily activity period following T manipulation is sufficient to explain most (79%) of the associated reduction in growth. Further, growth may have been constrained by additional energetic costs of increased ectoparasite load following T manipulation. Similar studies of the proximate behavioral, ecological, and physiological mechanisms involved in growth regulation should greatly improve our understanding of sexual size dimorphism.

Is the citrus-like plumage odorant of crested auklets (Aethia cristatella) a defense against lice?

Plumage odors may function as chemical defenses against ectoparasites in birds. We tested this hypothesis for crested auklets (Aethia cristatella), a species of colonial seabird that emits a very strong citrus-like odor from its plumage. This odorant contains known chemical repellents. We evaluated evidence for chemical defense in this species using two approaches. First, we exposed pigeon lice to the volatiles emitted by freshly plucked plumage and by whole specimens. Louse survivorship was compared between these treatments and two controls. Second, we compared louse abundance on crested auklets versus a closely related congener that nests in close association. Louse survivorship did not differ between crested auklet treatments and controls. Comparison of ectoparasite loads showed that crested auklets had significantly higher louse abundance than least auklets (A. pusilla), even after controlling for body size. Our results failed to support two expectations for chemical defense. Presence of the crested auklet plumage odorant in our experiments did not reduce louse life span. Presence of the aldehyde odorant in nature did not reduce louse abundance on crested auklets. Hence we conclude that the aldehyde odorant is not immediately lethal to lice at natural concentrations in plumage.

Prevalence and Colonization of Placobdella on Two Species of Freshwater Turtles (Graptemys geographica and Sternotherus odoratus)

It is generally accepted that bottom-dwelling turtles have a higher ectoparasite load than turtles that bask aerially because of effects of desiccation on ectoparasites, especially with regard to leeches. We compared number of leeches (primarily Placobdella parasitica) on field-caught Common Musk Turtles (Sternotherus odoratus) and Common Map Turtles (Graptemys geographica). The bottom-dwelling species S. odoratus had more than 20 times the number of leeches than the aerial-basking species G. geographica. We then exposed cleaned (leech-free) turtles to leeches in mesocosms (cattle tanks) to measure the rate of colonization. In this experiment, S. odoratus had more than four times the number of leeches as G. geographica after 24 h of exposure, even though G. geographica were unable to bask under these experimental conditions. We suggest that desiccation threat alone does not explain the species-specific differences in leech loads on aquatic turtles.

Additive effects of ectoparasites over reproductive attempts in the long‐lived alpine swift

Summary 1 Parasitism is a non-negligible cost of reproduction in wild organisms, and hosts are selected to partition resources optimally between current and future reproduction. While parents can compensate for the cost of parasitism by increasing their current reproductive investment, such change in resource allocation is expected to carry-over costs on future reproduction. 2 Life history theory predicts that because long-lived organisms have a high residual reproductive value, they should be more reluctant to increase parental effort in response to parasites. Also, when rearing successive infested broods, the cost of parasitism can cumulate over the years and hence be exacerbated by past infestations. 3 We tested these two predictions in the alpine swift Apus melba, a long-lived colonial bird that is infested intensely by the nest-based blood sucking louse-fly Crataerina melbae. For this purpose, we manipulated ectoparasite load over 3 consecutive years and measured reproductive parameters in successive breeding attempts of adults assigned randomly to ‘parasitized’ and ‘deparasitized’ treatments. 4 In current reproduction, fathers of experimentally parasitized broods produced a similar number of offspring as fathers from the deparasitized treatment, but the rearing period was prolonged by 4 days. Fathers that were assigned to the parasitized treatment in year x produced significantly fewer fledglings the following year x + 1 than those of the deparasitized treatment. The number of young produced by fathers in year x + 1 was correlated negatively with the number of days they cared for their brood in the previous year x. We also found a significant interaction between treatments performed over 2 successive years, with fathers of parasitized broods suffering a larger fitness loss if in the past they had already cared for a parasitized brood rather than for a deparasitized one. Similar effects of parasitism, although partly non-significant (0·05 0·10), were found in mothers. 5 Altogether, our results show that parasites can modify resource allocation between current and future reproduction in long-lived hosts, and that the cost of parasitism can cumulate over the years. It emphasizes the fact that effects of parasites can depend on past infestations and become apparent in future reproduction only.

Great frigatebirds, Fregata minor, choose mates that are genetically similar

Inbreeding occurs infrequently in most natural populations, with the level of relatedness between mates potentially being influenced by behavioural mechanisms of mate choice and spatial genetic structure of the population. We studied mate relatedness in a Hawaiian population of great frigatebirds with the expectation, based on frigatebird ecology, that mated pairs were unlikely to be more genetically similar than a random draw of adults from the breeding population. We used a paired analysis to compare the DNA fingerprint similarity of a female and her mate versus the same female and a random male that was breeding elsewhere on the same island. Overall, band-sharing scores between mates were higher than band-sharing scores between nonmates, and the mean coefficient of relatedness between mates was 0.082. Relatedness between mates was not a consequence of strong natal philopatry coupled with random mate choice: historical data revealed several recent between-island shifts in the location of the breeding colony, and the degree of genetic similarity between nonmates was not well predicted by the physical distance between their nest sites on Tern Island. Instead, females may deliberately choose related individuals as mates. Tests for a relationship between the genetic similarity of mates and the size and ectoparasite load of their 1-week-old chick were equivocal. The question of how and why females may be choosing genetically similar mates is unresolved, but it appears to be a consequence of active choice rather than spatial genetic structure or limited availability of unrelated mates.

Individual differences in microhabitat use in a Caribbean cleaning goby: a buffer effect in a marine species?

Summary Buffer effects occur when changes in population size result in the disproportionate use of poor‐quality habitats. Thus, at low population sizes high‐quality habitats are used preferentially. As population size increases an increasing proportion of the population uses poorer‐quality habitats. Assessment of the temporal and spatial variation in patterns of habitat occupancy can therefore shed light on the differences in quality between habitats and the individual fitness consequences of habitat choice. We provide the first evidence of the potential operation of a buffer effect for a site‐attached marine species. Caribbean cleaning gobies Elacatinus prochilos (Böhlke & Robins) occupy coral and sponge on fringing reefs in Barbados. For adult gobies, resource selection indices suggested a preference for sponge. However, as cleaning goby population size increased, the number of adult cleaning gobies occupying sponge increased more rapidly than the number occupying coral. In contrast, adults preferentially re‐colonized coral following experimental removals and at these low population densities the rate of population increase was greater on coral. Our results suggest that coral may be the preferred habitat, but in Barbados this habitat becomes saturated at very low population densities as a consequence of low client densities and ectoparasite loads. Thus, a larger proportion of the population occupies sponge at most observed population densities. Patterns of habitat occupancy with population size for recruits and juveniles suggest only a small difference in habitat quality between sponge and coral. Indeed, recruits and juveniles do not discriminate between sponge and coral. The population shift towards sponge rather than coral occupancy between recruitment and maturity may arise as a combination of differing survival of recruits and juveniles on coral and sponge and active movement of individuals towards sponge. Our results demonstrate that interactions among individuals are an integral part of population distribution and dynamics and are therefore important in future studies of habitat choice and its associated fitness consequences.

Efficacy of diatomaceous earth at reducing populations of nest-dwelling ectoparasites in Tree Swallows

Abstract Nest-dwelling parasites are known to have detrimental consequences for many birds, and thus it may be desirable for management practices to remove these parasites. In addition, manipulation of parasite loads is often necessary for studying host-parasite evolution. While there are various methods that are effective at reducing parasite loads in nests, many of them have shortcomings because they require specialized equipment, are time consuming, or involve toxic substances that may be dangerous to both birds and researchers. I evaluated the efficacy of simple-to-use, non-toxic diatomaceous earth (DE) at reducing ectoparasite loads in nests of Tree Swallows (Tachycineta bicolor) over two field seasons. Diatomaceous earth significantly reduced population sizes of bird fleas (Ceratophyllus idius) and various species of blow flies (Protocalliphora spp.) in both years. Diatomaceous earth appeared to be more effective at reducing the numbers of fleas, possibly because fleas have smaller body size and so ...

In situ evidence for ectoparasites as a proximate cause of cleaning interactions in reef fish

Although cleaning interactions are deemed a textbook example of mutualism, there is limited evidence that clients benefit from cleaning in terms of reduced ectoparasite loads. The proximate causes of cleaning behaviour are also contentious. We examined the effect of ectoparasite load (i.e. the number of larval gnathiid isopods) on client behaviour under natural conditions. Diel variation in gnathiid loads of longfin damselfish, Stegastes diencaeus, a common coral reef fish client of cleaning gobies ( Elacatinus spp.), was correlated with variation in gnathiid emergence from the substratum at sites in both Puerto Rico and St John, northeastern Caribbean. Both benthic emergence of gnathiids and their infestation on damselfish peaked in the morning. Concomitantly, clients spent significantly more time posing for and being inspected by cleaners in the morning than at other times of day. Our results corroborate recent experimental results on captive clients and are consistent with the mutualistic interpretation of cleaning symbioses.

Blood chemistry in relation to nutrition and ectoparasite load in Wilson?s storm-petrels Oceanites oceanicus

Haematology and plasma biochemistry values are useful tools for ecological research, providing information on the physiological state and adaptation of individuals to their habitat, changes in nutritional state of birds, body condition, the level of parasite infestation, etc. We studied the effect of stress factors on haematological and plasma biochemistry values in adult and nestling Wilson’s storm petrels Oceanites oceanicus (Aves, Procellariiformes). We measured packed cell volume, triglyceride levels, plasma protein levels, plasma hue and plasma corticosterone of nestlings and breeding adults at King George Island, South Shetland Islands. We used a snow storm as a natural experiment to test what effect starvation has on the stress response of nestlings. In particular, we predicted that: (1) plasma protein concentrations and plasma hue reflect ectoparasite load, (2) triglycerides and hue reflect the nutritional state, and (3) corticosterone levels increase with ectoparasite load and starvation. In line with our predictions, plasma triglycerides were higher in nestlings than adults, indicating a resorptive nutritional state in nestlings, during which dietary fat is deposited in adipose tissues. In adults, plasma triglycerides were positively correlated with body mass. Corticosterone levels increased in response to handling in adults, while we did not find a stress response in nestlings in good condition. However, nestlings sampled after their nests had been blocked by a snow storm showed a stress response in excess of that of adults. In nestlings sampled after the snow storm, corticosterone peak levels were positively correlated with the infestation intensity of the ectoparasite Philoceanus robertsi (Phthiraptera: Ischnocera), suggesting that the stress response is increased when more stressors act at the same time. In adults, plasma hue and proteins decreased with increasing ectoparasite load.

Ideal flea constraints on group living: unwanted public goods and the emergence of cooperation

Long ago, Hamilton (1971) proposed that the ‘‘selfish herd’’ effect, while primarily thought to reduce predation risk, might also apply to avoiding parasites. Solitary individuals suffer higher ectoparasite burdens if they lack conspecifics either to absorb collateral damage from the local ectoparasite population or to remove ectoparasites by allogrooming. By grouping, therefore, animals may reduce their individual risk of exposure to parasites (Mooring and Hart, 1992). This is important because there are significant fitness costs associated with ectoparasite loads. More ectoparasites take more blood, cause more irritation, increase the probability of infection, and decrease the time available for other activities, because grooming becomes a higher priority. These costs vary with group size because a greater number of hosts and shared den sites means ectoparasites are more likely to survive stochastic variation. The dynamics of parasite control might therefore present crucial constraints on group size and a novel origin for sociality itself. We present a model suggesting that these constraints may lead to an egalitarian system among social host species, who need to cooperate to get rid of their ectoparasites. Mobile ectoparasites are moderated by two mechanisms: (1) the dilution of ectoparasites toward an ideal free distribution (IFD) among hosts, and (2) the removal of ectoparasites by cooperative host allogrooming. Host interactions represent a ‘‘biological market,’’ in which the benefit of cooperation varies with the relative amount of the tradable commodity (the ectoparasites) each individual has. This is not, however, a normal market as the goods are unwanted. Nevertheless, the dilution effect means that all individuals in a group have a common stake in reducing the mean parasite burden, which may preclude or reduce any advantage of cheating. Predictions of the model were tested with empirical data from a longterm study of badgers, Meles meles, and their flea burdens in Wytham Woods, Oxford. A basic tenet in models of population dynamics (Hanski, 1999; Sutherland, 1996) is IFD, a general explanation for fluctuating distributions of animals as they move to find sites where the rewards are highest and individuals optimize their fitness (Fretwell, 1972; Fretwell and Lucas, 1970). Assuming individuals really are free (i.e., no resource defense and perfect information), this represents a process whereby consumers become diluted among all available sites. In short, the ratio between the numbers of individuals in sites A and B should be proportional to the relative availability of resources Behavioral Ecology Vol. 15 No. 1: 181–186 DOI: 10.1093/beheco/arg093

Ectoparasites: are they the proximate cause of cleaning interactions?

We tested the importance of ectoparasites in cleaning symbioses by comparing the activity of Caribbean cleaning gobies (Elacatinus evelynae) and of their clients during three daily periods (early morning, midday and late afternoon) in which ectoparasite availability varied naturally. Emergence from the benthos of gnathiid isopod larvae, the main target of cleaning goby predation, was higher at night, when cleaners are inactive, than during the day. Overall ectoparasite loads also tended to be higher on clients in the morning. This coincided with higher rates of visits to cleaning stations by client fish in the morning than at midday, but high rates of client visits were also recorded in the late afternoon. Clients were more likely to adopt stereotypical incitation poses, which increase the likelihood of being cleaned, in the morning than later in the day. Inspection bouts by cleaning gobies were longest in the morning. Cleaner and client behaviours therefore change predictably in response to natural diurnal variation in ectoparasite availability. These results add to a growing number of studies supporting the idea that cleaning symbioses are mutualisms dependent on ectoparasite removal.

Individual differences in microhabitat use in a caribbean cleaning goby: a buffer effect in a marine species?

Buffer effects occur when changes in population size result in the disproportionate use of poor‐quality sites or habitats. For species for which direct measurements of fitness differences between individuals are not possible, assessment of the temporal and spatial variations in patterns of habitat occupancy can therefore, shed light on the differences in quality between habitats and the individual fitness consequences of habitat choice. We provide the first evidence of the potential operation of a buffer effect for a site‐attached marine species. Caribbean cleaning gobies Elacatinus prochilos occupy coral and sponge substrata on fringing reefs in Barbados. Cleaning gobies at coral cleaning stations are frequently solitary or found in small groups, and spend 25 times longer cleaning than those on sponge. In contrast, sponge‐dwelling gobies exhibit highly stable, size‐structured dominance hierarchies in which, larger individuals are able to monopolize areas inside the sponge lumen with the highest abundance of the polychaete Haplosyllis spp, a favoured prey item. For adults, resource selection indices suggested a preference for sponge occupancy. As cleaning goby population size increased, however, the number of adult cleaning gobies occupying sponge substrata increased more rapidly than the number occupying coral habitat. Our results suggest that coral may be the preferred habitat, but in Barbados this habitat becomes saturated at very low population densities as a consequence of low client densities and ectoparasite loads. A larger proportion of the population, therefore, occupies sponge at most observed population densities. A population shift towards sponge rather than coral occupancy occurs between recruitment and maturity and may arise as a combination of differing survival of recruits and juveniles on coral and sponge and active movement of individuals towards sponge. Our results demonstrate that behavioural interactions are an integral part of population distribution and dynamics and are therefore, important in future studies of habitat choice and its associated fitness consequences.

Costs and benefits of a cleaning mutualism

Mutualisms can be thought of as ‘biological markets’ in which species trade resources, which can be manipulated by one or both participants. However, temporal and geographical variation in the outcome of mutualisms generates dynamic mosaics of co‐evolved interactions, therefore, outcomes of mutualistic interactions may be difficult to interpret with a ‘snapshot’ quantification of costs and benefits. Cleaning interactions are often used as classic examples of mutualism but assessing benefits to clients has been difficult. In this study we examined the outcome of the interaction between Caribbean cleaning gobies (Elacatinus evelynae) and longfin damselfish (Stegastes diencaeus), by comparing interactions at a number of locations. Previously we have shown that longfin damselfish benefit from cleaning interactions by a significant but small reduction in ectoparasite loads and we suggested that the costs of travelling and seeking cleaners by territorial damselfish may limit the net benefit of cleaning to the client (Cheney & Côté, 2001). Here, we investigate how the relationship alters between geographical locations and in one site, over 3 consecutive years, under varying environmental conditions to elucidate key components affecting cleaning symbioses.

Up or down? Explaining the variability of communication signals in cleaning symbioses

In this study, we used cleaning symbioses among coral reef fishes as a model system to investigate the form and function of signalling in interspecific mutualisms. More specifically, we examined the causes and significance of inter‐specific and inter‐individual variation in the design of client solicitation poses in cleaning interactions with Caribbean cleaning gobies (Elacatinus spp). Using empirical data collected during field observations at cleaning stations, we tested three hypotheses: (1) The form of client incitation poses depends on species‐specific features; (2) Intraspecific variability in the form of client poses reflects the strength of each cleaner‐client relationship; and (3) Client individuals that deviate from a clear species‐specific form of pose will receive a different cleaning service. As predicted by (1), we found that the type of incitation pose was related to client body size, with small species performing mainly head‐down displays which may facilitate retreat into coral cavities upon predator approach. There was nevertheless some intraspecific variation in the type of display performed by clients, which was negatively related to client ectoparasite load, as predicted by (2). Hence, species with higher ectoparasite loads, and thus with a greater need to be cleaned, were less variable in display form than clients with fewer ectoparasites. Finally, cleaning gobies inspected for longer those individual clients that performed the species‐specific solicitation poses (3). We conclude that solicitation poses function to minimize uncertainty about a client's need to be cleaned and that their design has been partly determined by the risk of predation on posing clients.