In-situ Observations of Symbionts on Medusae Occurring in Japan,Thailand, Indonesia and Malaysia

Abstract

During an ecological investigation on symbionts of medusae in Eastern and Southeastern Asian waters, seven species of hydro- and scypho-medusae were found to harbor a wide variety of invertebrates and fishes: the isopod Idotea metallica and the nudibranch Fiona pinnata on the chondrophoran Vellela vellela; the actiniarian Peachia quinquecapitata on the leptomedusa Aequorea coerulescens; the butterfish Psenopsis anomala and the hyperiid amphipod Hyperia galba associated with the semaestome Chrysaora melanaster; H. galba on the semaestome Aurelia limbata; metacercariae of three species found in the mesogloea of a semaestome, Aurelia sp.; the ophiuroid Ophiocnemis marmorata, the caridean shrimp Latreutes spp., and the shrimp scad Alepes djedaba on the rhizostome Rhopilema hispidum; the swimming crab Charybdis feriata and A. djedaba on the rhizostome Versuriga anadyomene. Juveniles of benthic organisms such as crabs and ophiuroids seem to become hitchhikers for dispersal, while juvenile fi sh utilize medusae as refugia against predation. Since the previous and present studies have shown that edible rhizostomes are associated with many kinds of symbionts, fisheries for these jelly fishes possibly hinder the recruitment of symbionts such as decapods, ophiuroids and fish.