Dim light vision of Squilla mantis L

Abstract

The anatomy of the eye of Squilla mantis and the geometrical optics derived from it are briefly described. The shape and size of the electroretinogram (ERG) are dependent on a) position where it is picked up, b) the light intensity, and c) the change of intensity. Single-fiber analysis confirms the results obtained by the anatomy and the ERG of the eye. Frequency of response of a single secondary fiber to intensity changes of light is proportional to the derivate dI/dt ( I = intensity; t = time). The Squilla sees a moving object as the sum of the intensity changes caused by that object, varied in time and space. The eyes have a maximum of sensitivity for light of 535–555 mµ wavelength, and a second maximum in the near ultraviolet light, the latter partly seen as green fluorescence due to an eye pigment. Anatomy, physiology, and the environmental conditions have been combined to explain the vision of this animal, adapted to his life in the blue-violet twilight of the deeper Mediterranean sea.

Evolutionary variation in the expression of phenotypically plastic color vision in Caribbean mantis shrimps, genus Neogonodactylus

“…Many species in the superfamilies Gonodactyloidea and Lysiosquilloidea have an intricate color vision system with up to ten photoreceptor classes in the "visible" spectrum (Manning et al 1984;Cronin and Marshall 1989b;Cronin et al 1994c;Cronin et al 1994d;Marshall and Oberwinkler 1999;Harling 2000) as well as four or more classes of ultraviolet-sensitive receptors (Schiff 1963;Cronin et al 1994d;Marshall and Oberwinkler 1999). Some retinal classes of ommatidia contain colored intrarhabdomal filters that narrowly tune the sensitivities of underlying photoreceptors (Marshall et al 1991;Cronin et al 1994a).…”

A mantis shrimp wearing sun‐glasses

“…In fact it can only change due to the muscles between the cones and attached to the cornea. Bundles of muscles have been observed also in S. mantis (Schiff, 1963), in which the retina is pulled towards the cornea during dark adaptation, widening the cones and lengthening the rhabdoms (Schiff, 1974) and thus increasing the acceptance angle. In Squilla these muscles have been observed to contract, while in Lysiosquillina the muscle bundles are heavier and presumably subserve the same purpose, i.e., adapting the eye to the dark or to the light.…”

Photomechanical adaptation in the eyes ofSquilla mantis(Crustacea, Stomatopoda)

“…Photomechanical light-, dark-adaptation in compound eyes has been described for the eyes of Limulus (Chamberlain & Barlow, 1987;Ankrom & Chamberlain, 2002) and Squilla mantis (Schiff, 1963(Schiff, , 1974Schönenberger, 1977). It is difficult to obtain absolute values of the changes in light-, dark-adaptation because ommatidia have different sizes in different regions of the eye, sizes depend on the size of the animal and sections are usually not exactly along the optical axes.…”

“…During dark adaptation the cones become shorter and the retina longer (Schiff, 1963(Schiff, , 1974Schönenberger, 1977), while in light adaptation the opposite occurs. The angular sensitivity function of an ommatidium is a gaussian curve which depends upon the angle of the incident light rays and was given by Snyder et al (1977):…”