Photoresponses of the Compound Eye of the Sandhopper Talitrus saltator (Crustacea, Amphipoda) in the Ultraviolet-Blue Range

Abstract

The semi-terrestrial sandhopper Talitrus saltator uses celestial visual cues to orient along the sea-land axis of the beach. Previous spectral-filtering experiments suggested that it perceives directional information from wavelengths in the ultraviolet (UV)-blue range. Binary choice experiments between dark and UV (380-nm) light carried out on dark-adapted individuals of T. saltator showed photopositive movement to UV. Morphologically, each ommatidium in the eye consists of five retinula cells, four large and one small. In electroretinogram experiments, sensitivity of the dark-adapted eye is dominated by a receptor maximally sensitive at about 390-450 nm and secondarily sensitive at about 500-550 nm. Selective light-adaptation experiments at 580 nm showed the apparent sensitivity decreasing at around the secondary sensitive range, thus disclosing the existence of UV-blue photoreceptor cells. Here the existence of UV-blue detection is confirmed, and evidence is provided that green and UV-blue visual pigments are located in the large and small retinula cells, respectively.

The visual system of the genetically tractable crustaceanParhyale hawaiensis: diversification of eyes and visual circuits associated with low-resolution vision

“…Although the specific spectral properties of each opsin can only be determined by direct measurements of the wavelength of maximal absorbance, the finding that PhOpsin1 and PhOpsin2 are most closely related to opsins with long- and mid-wavelength sensitivities, respectively, suggests their most likely absorbance spectra. This is consistent with previous work on talitrid amphipods which revealed two peaks of sensitivity, at 520 and 430 nm [32, 33].…”

“…Amphipods are widely distributed aquatic and semi-terrestrial crustaceans, belonging to one of the major evolutionary branches of crustaceans, the malacostracans. The visual system of amphipods remains relatively unexplored [29-33], though some species exhibit extreme adaptations (e.g. [34]).…”

The skylight gradient of luminance helps sandhoppers in sun and moon identification

“…Moreover, it is 7 orders of magnitude higher than the night sky luminance, and this could explain why the gradient of the open night sky, with a shape similar to the day one, is not perceived, as the luminance values could be too low. This hypothesis is supported by previous electroretinogram (ERG) findings [see fig.3 of Ugolini et al (Ugolini et al, 2010) ), the signals of each response were 'at the limit for detection above noise level'. Moreover, tests on orientation capacity carried out at sunset confirmed the good agreement with the ERG results [see fig.4 of Ugolini et al (Ugolini et al, 2004)].…”

Experimental Change of the Orientation of Two Populations of Talitrus saltator (Crustacea Amphipoda Talitridae) from Cap Bon (North‐Eastern Tunisia)

“…Mezzetti & Scapini () and Ugolini et al. () in Talitrus saltator and Cohen et al. () in Talorchestia longicornis s showed the importance of visual pigments in the perception of different specific wavelengths.…”