The Crown-of-thorns starfish (COTS; Acanthaster planci) are mobile coral predators that are prevalent on the Great Barrier Reef (GBR) and reefs across the Indo-Pacific. They are highly fecund echinoderms, a feature that has contributed to extensive population outbreaks, causing detrimentaldamage to coral reefs. In fact, the past three decades have seen a steady decline in over half of all coral cover on the GBR, with 37% of this due to COTS. Whilst equipped with basic visual sense, COTS primarily navigate their environment using chemosensory mechanisms. To help elucidate the neural mechanism of chemosensation in COTS, we performed an ultrastructure investigation followed by multiomics analysis of the COTS radial nerve cord, a tissue that controls the numerous arms and chemosensory tentacles. Scanning electron micrographs revealed that the ventral surface of the radial nerve is completely covered in bulbous structures. Subsequent transmission electron micrographs showed that these novel formations are protrusions of the ectoneural region of the radial nerve and are populated with cilia and large granular secretory vesicles. Within the radial nerve cord, a repertoire of neurotransmitters was identified including neuropeptides and G-protein coupled receptors. Neuropeptides match to both known and novel precursors, some of which may be unique to starfish and possibly even the COTS. Our analysis provides the first exploration into the radial nerve cord of this coral predator, allowing for dentification of species-specific features that may reveal vulnerabilities to be target for pest control.
17th International Symposium on Olfaction and Taste (ISOT2016), Yokohama, Japan 5-9 June 2016