EYES OF DEEP SEA CRUSTACEANS

Abstract

1. Three species of acanthephyrids have been taken in closing nets in the region of the Sargasso Sea and in slope water near the Gulf Stream in numbers sufficient so that their vertical distribution is quite accurately known. Acanthephyra purpurea and Systellaspis debilis are found mostly within the photic zone. Hymenodora glacialis inhabits a region below that to which sunlight penetrates. 2. The eyes of A. purpurea and S. debilis are quite similar structurally to the eyes of shallow-water prawns, except that there is less screening pigment. 3. Species of Systellaspis and Oplophorus possess photophores and the eyes of these forms are larger in proportion to body size than the eyes of those acanthephyrids which lack photophores. 4. The eyes of H. glacialis are quite degenerate. The rhabdomes, and both distal and proximal pigments are lacking. The reflecting pigment layer is well developed. 5. Characteristic movements of the proximal pigment of S. debilis and A. purpurea occur as the result of light adaptation.