Observations on the specific associations found between scyphomedusae and commensal fish and invertebrates in the Philippines

Abstract

Our observations on scyphomedusae from selected Philippine embayments identified specific animals commensal with five species of rhizostome scyphomedusae, Acromitoides purpurus, Mastigias sp., Phyllorhiza punctata, Rhopilema hispidum and Versuriga anadyomene. Acromitoides purpurus medusae harbor the crab Charybdis feriata, the carangid fish Alepes djedaba and the poecilostomatoid copepod Paramacrochiron sp. The carangid A. djedaba was an associate of the blue morph of A. purpurus and Rhopilema hispidum in Panguil Bay. A black-pigmented Alepes sp. was found associated with burgundy A. purpurus medusae in Carigara Bay. Charybdis feriata juveniles are common commensals of all morphs of A. purpurus, R. hispidum and P. punctata medusae. Only the zooxanthelate Mastigias sp. lacked animal symbionts. We invoke the “meeting-point hypothesis” and the general theory of fish aggregation to floating structures to explain fish symbiosis with their medusan hosts. The invertebrate-medusa associations are attributed to feeding behaviors and predator avoidance by resident commensals. This study provides record of the poorly studied scyphozoan species and their association with animals in Philippine waters. Finally, we discuss the potential reasons why the golden spotted jellyfish, Mastigias sp., appears to lack animal commensals.