Differentially expressed venoms in functionally specialized polyps of the colonial hydrozoan Hydractinia symbiolongicarpus

Abstract

Cnidaria (jellyfish, hydra, sea anemones, etc.) represent the earliest diverging venomous animal lineage. Venom is deployed in cnidarians for predation, defense, competition, and digestion. Recent evidence suggests venom composition can be influenced by age, diet, geography, and the presence of predators or prey. Although venom production and maintenance are central to the life history of cnidarians, little is known about their venom composition with respect to biological or ecological function. Hydractiniid hydrozoans are an ideal system for studying venom function and evolution due to their functionally specialized tissue types and complex life cycles. The hydractiniid Hydractinia symbiolongicarpus displays a division of labor among its polyps that comprise the colony: dactylozooids (defense and predation), gastrozooids (feeding and digestion), and gonozooids (reproduction). Using an existing transcriptome of the different functional polyp types of H. symbiolongicarpus, we characterized the putative venom components and venom expression between these tissues. By using functionally specific polyps of H. symbiolongicarpus, we can determine how the venom arsenal varies for specific tasks. Understanding how venom composition is influenced by various developmental and ecological factors will lead to a better understanding of venom diversity and function in cnidarians.