Regionalization in the eye of the grapsid crab Neohelice granulata (=Chasmagnathus granulatus): variation of resolution and facet diameters.

BERÓN DE ASTRADA, MARTÍN; BENGOCHEA, MERCEDES; MEDAN, VIOLETA; TOMSIC, DANIEL

JOURNAL OF COMPARATIVE PHYSIOLOGY A-SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY

SPRINGER

Lugar: Berlin; Año: 2012 vol. 198 p. 173 - 180

0340-7594

Crabs have panoramic compound eyes, whichcan show marked regional specializations of visual acuity.These specializations are thought to be related to the particularfeatures of the animal’s ecological environment. Modernknowledge on the neuroanatomy and neurophysiologyof the crabs’ visual system mainly derives from studiesperformed in the grapsid crab Neohelice granulata(=Chasmagnathus granulatus). However, the organizationof the visual sampling elements across the eye surface ofthis animal had not yet been addressed. We analyzed thesampling resolution across the eye of Neohelice by measuringthe pseudopupil displacement with a goniometer. Inaddition, we measured the facet sizes in the diVerentregions of the eye. We found that Neohelice possesses anacute band of high vertical resolution around the eye equatorand an increase in horizontal sampling resolution andlenses diameter towards the lateral side of the eye. Therefore,the analysis of the optical apparatus indicates that thiscrab possesses greater visual acuity around the equator andat the lateral side of the eye. These specializations are comparedwith those found in diVerent species of crabs and arediscussed in connection to the particular ecological featuresof Neohelice’s habitat.