Shape, colour plasticity, and habitat use indicate morph-specific camouflage strategies in a marine shrimp

Abstract

BackgroundColour and shape polymorphisms are important features of many species and may allow individuals to exploit a wider array of habitats, including through behavioural differences among morphs. In addition, differences among individuals in behaviour and morphology may reflect different strategies, for example utilising different approaches to camouflage. Hippolyte obliquimanus is a small shrimp species inhabiting different shallow-water vegetated habitats. Populations comprise two main morphs: homogeneous shrimp of variable colour (H) and transparent individuals with coloured stripes (ST). These morphs follow different distribution patterns between their main algal habitats; the brown weed Sargassum furcatum and the pink-red weed Galaxaura marginata. In this study, we first investigated morph-specific colour change and habitat selection, as mechanisms underlying camouflage and spatial distribution patterns in nature. Then, we examined habitat fidelity, mobility, and morphological traits, further indicating patterns of habitat use.ResultsH shrimp are capable of changing colour in just a few days towards their algal background, achieving better concealment in the more marginal, and less preferred, red weed habitat. Furthermore, laboratory trials showed that habitat fidelity is higher for H shrimp, whereas swimming activity is higher for the ST morph, aligned to morphological evidence indicating these two morphs comprise a more benthic (H) and a more pelagic (ST) life-style, respectively.ConclusionsResults suggest that H shrimp utilise a camouflage strategy specialised to a limited number of backgrounds at any one time, whereas ST individuals comprise a phenotype with more generalist camouflage (transparency) linked to a more generalist background utilisation. The coexistence within a population of distinct morphotypes with apparently alternative strategies of habitat use and camouflage may reflect differential responses to substantial seasonal changes in macroalgal cover. Our findings also demonstrate how colour change, behaviour, morphology, and background use all interact in achieving camouflage.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0796-8) contains supplementary material, which is available to authorized users.

Camouflage through colour change: mechanisms, adaptive value and ecological significance

“…For example, diet is known to influence coloration in some spiders [27]. In Hippolyte prawns (figures 1 and 2), effective colour change from one morph to another seems to require the presence of real seaweed, rather than colour matched artificial backgrounds [28], although this does not discount a role of vision. In caterpillars, studies (some stemming back to Poulton, e.g.…”

Color patterns of the hermit crab Calcinus tibicen (Herbst, 1791) fail to indicate high genetic variation within COI gene

“…It means that individuals with orange or green chelae inhabit the same region, nevertheless, they can occupy different habitats with distinct background coloration, what might represent camouflage aspects, as already reported for other decapods (e.g. Bauer, 1981;Duarte et al, 2016). Morphology, coloration, and behavior can be linked to different ecological and evolutionary predation pressure under the same habitat (Hacker and Madin, 1991), related to predator color vision and predator color acuity (Endler, 1978).…”

“…The tons of the animals, in general, tend to be similar to their backgrounds (e.g. Poulton, 1890;Duarte et al, 2016), and in this case, some of the animals were collected in association and/or close to the red or green algae banks (FLM, pers. obs.).…”

The Color of Marine Shrimps and Its Role in the Aquaculture

“…They are capable of changing color in just a few days towards to the type of background in which they are and the affi nity of habitats higher for H shrimp, whereas swimming activity is higher for the ST morph, which indicates that strategy H shrimp tend to have a more benign life-style [18]. It is known that shrimps are able to change body color in relation to environmental conditions [19].…”