Beachside banquet: Ants' appetite for shipwrecked siphonophores

Abstract

As the importance of both the high seas and gelatinous zooplankton is continuously revealed, it is important to document basic interactions. Physalia are venomous siphonophores, commonly called ‘Man of War’ or ‘Bluebottles’, that use a gas filled float to sail the high seas. Despite being the most conspicuous member of the neustonic ecosystem (the ecosystem at the open ocean's surface), little is known about its life history nor its ecosystem contributions. Herein, two ant species, Solenopsis cf. geminata and Iridomyrmex cf. anceps, were observed foraging on beached colonies of Physalia cf. utriculus in Guam, Micronesia. Ants explored fresh colonies with untriggered stinging cells, yet only disassembled and transported partially dry or degraded colonies. Observations like this improve the understanding of cross-ecosystem dynamics between the coastal and neustonic ecosystem, island trophic structures, and the contribution of gelatinous zooplankton.