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Intracerebral ocelli in an amphipod: extraretinal photoreceptors of the sandhopper Talitrus saltator (Crustacea, Amphipoda)
Author(s) -
FrelonRaimond Maryline,
MeyerRochow V. Benno,
Ugolini Alberto,
Martin Gilbert
Publication year - 2002
Publication title -
invertebrate biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.486
H-Index - 42
eISSN - 1744-7410
pISSN - 1077-8306
DOI - 10.1111/j.1744-7410.2002.tb00131.x
Subject(s) - simple eye in invertebrates , crustacean , amphipoda , biology , anatomy , dorsum , zoology
. No morphological clues on the amphipod head indicate the existence of ocelli. However, as in several isopod species studied so far, two rudimentary photoreceptors are integrated into the medio‐dorsal part of the brain. This electron microscopical study of the photoreceptors is the first report on the presence of ocelli in amphipods. Each ocellus is made up of 3 receptor cells which contribute to the formation of a photoreceptive surface (the rhabdom) formed by tightly packed microvilli. The rhabdoms are twisted and irregular in outline. Membrane turnover is suggested by the presence of different kinds of lysosomes. Lacking dioptric lenses, these photoreceptors are not likely to be involved in image formation but may function as appraisers of ambient light intensity. Physiological and behavioral studies will, henceforth, have to take into account these unexpected ocelli, which may represent remnants of the naupliar eye.