DEVELOPMENTAL DYNAMICS OF GREEN FLUORESCENT CHROMATOPHORES IN THE DAGGERBLADE GRASS SHRIMP, PALAEMONETES PUGIO HOLTHUIS, 1949 (DECAPODA, CARIDEA, PALAEMONIDAE)

Abstract

The daggerblade grass shrimp, Palaemonetes pugio Holthuis 1949 relies heavily on transparency as the primary form of camouflage yet possess several types of pigmented chromatophores located throughout the body. A distinct sub-population of yellow/white chromatophores have been discovered to exhibit brilliant green fluorescence. These cells develop in the embryo and are the primary chromatophore present in larval organisms. Post-larval grass shrimp undergo a major restructuring of the pattern and morphology of fluorescent chromatophores after metamorphosis with chromatophores found uniformly distributed throughout the body and at high concentration on the hepatopancreas and the eye stalks. In adult P. pugio the number of fluorescent chromatophores is significantly reduced and fluorescence is limited to only a subset of these chromatophores. The novel fluorescent properties of these cells, there relatively high abundance during early life stages, and pattern of development, suggest important cellular functions for these fluorescent chromatophores in grass shrimp.