Spectral sensitivity of four species of fiddler crabs (Uca pugnax, Uca pugilator, Uca vomeris and Uca tangeri) measured by in situ microspectrophotometry
Loading...
Links to Files
Author/Creator
Author/Creator ORCID
Date
2007-01-17
Type of Work
Department
Program
Citation of Original Publication
Joana M. Jordão, Thomas W. Cronin, Rui F. Oliveira, Spectral sensitivity of four species of fiddler crabs (Uca pugnax, Uca pugilator, Uca vomeris and Uca tangeri) measured by in situ microspectrophotometry, Journal of Experimental Biology 2007 210: 447-453; doi: 10.1242/jeb.02658
Rights
This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
non-commercial use only
non-commercial use only
Abstract
Fiddler crabs have compound eyes that are structurally
fairly well understood. However, there has been much
debate regarding their spectral sensitivity and capacity to
enable colour discrimination. We examined the visual
pigments of two North-American species (Uca pugnax and
U. pugilator), one species from the Indo-West Pacific (U.
vomeris) and the only Eastern-Atlantic species (U. tangeri)
of fiddler crabs using in situ microspectrophotometry of
frozen sections of dark-adapted eyes. Only one spectral
class of visual receptor was found in the larger (R1–7)
retinular cells of each species, with maximum absorption
peaking between 508·nm and 530·nm (depending upon
species). The R8 retinular cell, that might contain a shortwavelength
sensitive photopigment and provide a basis for
colour vision, was too small to analyze by these methods.
Rhabdoms were lined with screening pigment which
strongly influenced each species’ spectral sensitivity,
sharpening the peak and shifting the maximum towards
longer wavelengths, on occasion to as far as the 600·nm
region. We hypothesize that sensitivity to longer
wavelengths enhances contrast between background (blue
sky or tall vegetation) and the male major claw during the
waving display.