Extended Maternal Care Observed in Parallorchestes Ochotensis (Amphipoda, Gammaridea, Talitroidea, Hyalidae)

Abstract

Several peracarid crustaceans have been shown to engage in extended maternal care for their growing offspring after the juveniles hatch from the brood pouch of the female. In this study, we describe the maternal care of the epibenthic gammaridan Parallorchestes ochotensis Brandt and examine its ecological implications. The juveniles stayed in the female’s expanded brood pouch for at least seven weeks after hatching. The duration of extended maternal care of P. ochotensis was comparatively longer and the growth of P. ochotensis juveniles slower than reported for other epibenthic peracarids. The juveniles molted at least twice whilst in maternal care. This species probably has an annual life span, and they reproduce only once a year. In P. ochotensis, maternal care was shown to constrain juvenile growth in the experimental predator-free conditions, contrary to other epibenthic peracarids. Most epibenthic peracarid species with extended maternal care are suspension feeders, but P. ochotensis is an herbivore so probably maternal care of this species limits juvenile feeding opportunities and results in a decrease of juvenile growth. However, where normal predation exists, maternal protection contributes significantly to juvenile survival. In P. ochotensis, to enhance relatively low fecundity in conditions where predation pressure is high, extended maternal care for relatively long periods is necessary to protect offspring even if it constrains juvenile growth.