Acanthaster species, better known as the Crown-of-Thorns Starfish (COTS), have gained major attention during the past century due to its corallivorus and fecund nature often leading to localised population outbreaks with the ability to decimate entire coral reef ecosystems. These effects ultimately lead to significant impacts to biodiversity and coral cover loss that also effects the economy. Although multiple population control strategies have been implemented on impacted reefs, attempts are often very laborious, expensive, and associated with dangers for diver personnel performing the various procedures (e.g., manual injection of toxin). Novel methods are therefore required to facilitate approaches that simplify current strategies without negatively impacting the reef environment. Elucidation of COTS semiochemical signalling leading to the formation of aggregations (that ultimately enhance fertilization success), are seen as key factors to understand the complexity of COTS reproductive biology. Successfully mimicking these semiochemicals associated with attraction responses could be utilised in the development of strategies where individuals could be pulled towards the source of attractant, and thus alleviate processes that currently require spatially broad efforts. In turn, a COTS attractant could also be used to disperse large aggregations during spawning events, thereby reducing percentual fertilization of gametes and thereby reduce future population numbers. This PhD Thesis aimed to elucidate key semiochemical attractants, as well as investigate a recognised endogenous peptide that stimulates spawning.