The nauplius eye and frontal organs in decapoda (crustacea)

Abstract

The present investigation concerns the nauplius eye and frontal organs in decapod Crustaceans. Representatives from all groups of the Decapoda are included. Some of the more important results are abstracted. The nauplius eye in several families within the Eucyphidea is more complicated than generally believed. It consists of a nauplius eye s. s. with three cups and three sensory cells in each and the incorporated dorsal frontal organ, which functions as an eye. The sensory cells are everse. The dorsal frontal organ is thus intimately connected with the nauplius eye s. s. and must not be mixed up with the eye papilla and the sensory pore X organ. The dorsal frontal organ is subjected to a considerable degree of variation. As part of a nauplius eye s, 1. as mentioned above it is an eye. In many species all over the Decapoda the frontal organ is reduced. A line of transformation can be shown from eye appearance through intermediate stages to “globuli” cells situated in the ganglion layer of the brain. The ventral frontal organ is more common than formerly believed and its paired nature is stressed. The author acceds to Hanström's hypothesis (1926) concerning the phytogeny of the frontal organs.