Anatomy and ultrastructural organisation of the eye of the Mediterranean slipper lobster,Scyllarides latus:preliminary results

Abstract

Gross anatomical organisation and ultrastructure of day-and nighttime light-and dark-adapted eyes of the Mediterranean slipper lobster, Scyllarides latus, revealed that the retina of this crustacean reacts to different ambient light intensities with photomechanical changes, involving principally screening and reflecting pigments and that a circadian component controls full darkadaptation. Although similarities to the earlier investigated eyes of spiny and rock lobsters exist, one significant difference concerns the spindle shape of the adult slipper lobster rhabdom and the banded structure of the latter, caused by orthogonallyaligned layers of microvilli. The rhabdom structure M07115; Online publication date 24 February 2009 Received 30 November 2007; accepted 21 February 2008of adult slipper lobsters thus resembles that of larval rock lobsters and suggests sensitivity to polarised light. The extensive clear-zone between dioptric and light-perceiving elements in the eye of the slipper lobster, the relatively large number of ommatidia and facet diameters of 90 µm, moreover, suggest that the slipper lobster eye is particularly suited for vision in a dimly lit environment and operates on the principle of "reflecting superposition optics". The position of the eyes on the head and the thick cornea are indicative of a need to protect the eyes against physical damage.

Slipper lobster (Crustacea, Decapoda, Scyllaridae) fisheries off the southeastern coast of Brazil: I. Exploitation patterns between 23°00′ and 29°65′S

“…These factors appear to explain the increased abundance of slipper lobsters in "Farol do Boi" relative to open areas where the soft substrate supplies no shelter. Previous studies have reported that similar rocky outcrops are preferred by S. latus in the Azores and Mediterranean Sea (Spanier et al, 1988;Martins, 1985;Spanier and e Almog-Shtayer, 1992;Barshaw and Spanier, 1994;Spanier and Lavalli, 1998;Lavalli and Spanier, 2001;Lau et al, 2009), S. astori in the Galapagos islands (Hearn, 2006), S. aequinoctialis and S. nodifer in Florida (Sharp et al, 2007) and S. squammosus and S. haanii in Hawaii (Dinardo and Moffitt, 2007). …”

Treatise on Zoology - Anatomy, Taxonomy, Biology. The Crustacea, Volume 9 Part A

“…While both Panulirus and Jasus species have been investigated in palinurids, thus far only one study has been undertaken on the eye structure of scyllarids (Scyllarides sp.). Like the palinurid eye, the scyllarid eye consists of numerous ommatidia separated from the retinular cells by a clear zone that is composed of cytoplasmic extensions from the proximal end of the cone cells as well as shielding pigment cells (Lau et al, 2009). There are eight retinula cells per ommatidium, seven of which contribute to a central rhabdom that is spindle-shaped.…”

“…The eighth cell contributes only in a minor way to the rhabdom. Axons emerging from the retinular cells are bundled into clusters (Lau et al, 2009). Compared with Jasus spp., Scyllarides spp.…”

“…Compared with Jasus spp., Scyllarides spp. have larger facets, which suggests that visual acuity, while important, is less important in the deeper water of the scyllarids than in the shallower water that species of palinurids inhabit (Lau et al, 2009). Given that the eye structure is typical of a nocturnally active marine animal (Land & Nilsson, 2002) and that even during the day it is likely that many Scyllarides spp.…”

“…Given that the eye structure is typical of a nocturnally active marine animal (Land & Nilsson, 2002) and that even during the day it is likely that many Scyllarides spp. are in dimly-lit waters, the structure of the rhabdom (spindle-shaped), while conducive to polarization sensitivity, may be a neotenous feature left from the larval form in which polarized vision would have been useful (Lau et al, 2009).…”