pubmed.ncbi.nlm.nih.gov

Doors to the Homes: Signal Potential of Red Coloration of Claws in Social Hermit Crabs - PubMed

  • ️Sun Jan 01 2023

Doors to the Homes: Signal Potential of Red Coloration of Claws in Social Hermit Crabs

C T M Doherty et al. Integr Org Biol. 2023.

Abstract

Red coloration on a signaler's body may be an informative signal in many animals. For species that inhabit architecture (e.g., burrows, nests, or other structures), certain parts of the body are more exposed than others, potentially serving as superior platforms for signaling via coloration. Yet whether animals differentially advertise red coloration on body parts that are more versus less exposed from their architecture remains to be tested. Here, we systematically quantified red coloration in social hermit crabs (Coenobita compressus). These crabs inhabit architecturally remodeled shells and have claws that visibly block the shell entrance, like doors to their homes. We hypothesized that red coloration of claws may be a signal of resource-holding potential (RHP). Consistent with this RHP signaling hypothesis, we found that within the same individuals' bodies, exposed claws showed significantly greater red coloration than unexposed carapaces. Furthermore, larger body size predicted greater red coloration of claws. Competing hypotheses (e.g., interspecific signaling, camouflage, and UV protection), while not explicitly tested, nevertheless appear unlikely based on natural history. Red claw coloration may therefore function as a signal to conspecifics, and experiments are now needed to test recipient responses. Broadly, relative to surrounding architecture, exposed body surfaces offer rich potential as signaling platforms for coloration.

© The Author(s) 2023. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.

PubMed Disclaimer

Conflict of interest statement

None declared.

Figures

Fig. 1
Fig. 1

Measurements of body color, in relation to shell architecture, within the social hermit crab (Coenobita compressus). (A) Photograph of color variation across individuals (arrayed from largest to smallest from left to right). Note that only part of each individual's body, particularly its enlarged left claw, is exposed out of the shell architecture, being visible as a “door to the home.” (B) Reflectance was measured using a Jaz spectrometer. (C) Color measurements focused on two areas of crabs’ bodies: exposed claws (arrow on left) and unexposed carapaces (arrow on right). Individual pictured has been removed from its shell to show both areas. (D) Example of a reflectance curve for the claw of a male, including the formula used to calculate red coloration. (Photos for A and C: Mark Laidre; photo for B: Elliott Steele).

Fig. 2
Fig. 2

Red coloration (mean ± SE) of exposed claws versus unexposed carapaces for N = 72 individuals.

Fig. 3
Fig. 3

Interaction plot of red coloration of body parts against overall body size (shield length in mm) for N = 72 individuals. Exposed claws are shown with black dots and black trendline, and unexposed carapaces are shown with gray dots and gray trendline.

Fig. 4
Fig. 4

(A) Linear regression of exposed claw area (mm2) against overall body size (shield length in mm) for N = 72 individuals. Red arrows show residuals (most positive and most negative) for differences from the predicted line. (B) Linear regression of red coloration of exposed claws against residuals of exposed claw area. Related data points highlighted in (A) and (B) for reference.

Similar articles

References

    1. Abrams P. 1978. Shell selection and utilization in a terrestrial hermit crab, Coenobita compressus (H. Milne Edwards). Oecologia 34: 239–53. - PubMed
    1. Ahmadkelayeh S, Hawboldt K. 2020. Extraction of lipids and astaxanthin from crustacean by-products: a review on supercritical CO2 extraction. Trends Food Sci Technol 103: 94–10.
    1. Alcaraz G, García-Cabello KN. 2017. Feeding and metabolic compensations in response to different foraging costs. Hydrobiologia 787: 217–27.
    1. Alcaraz G, Toledo B, Burciaga LM. 2020. The energetic costs of living in the surf and impacts on zonation of shells occupied by hermit crabs. J Exp Biol 223: jeb222703. - PubMed
    1. Alonso-Alvarez C, Bertrand S, Devevey G, Gaillard M, Prost J, Faivre B, Sorci G. 2004. An experimental test of the dose-dependent effect of carotenoids and immune activation on sexual signals and antioxidant activity. Am Nat 164: 651–9. - PubMed

LinkOut - more resources