Establishing Symbiosis in the Bobtail Squid

Beneficial symbiosis enables organisms to form relationships essential for survival, providing a range of benefits, from environmental regulation and defence to meeting nutritional needs. An important example of this relationship is between the bobtail squid, Euprymna scolopes (ES), and the bacterium Vibrio fischeri (VF). By allowing the bioluminescent bacteria to colonise the squid’s specialised light organ, ES gains the ability to camouflage itself through counter-illumination. In doing so, it facilitates its nocturnal hunting behaviours. Several models and studies have been conducted on the establishment of this symbiosis. But several aspects of the physical colonisation process remain poorly understood. In particular, during early colonisation, fluid flows are crucial for directing bacteria to the light organ. To study these flows, we applied the Method of Regularized Stokeslets, developing a computational fluid dynamics model to explore the fluid dynamics within the ES during the colonisation process. The model aims to approximate the breathing dynamics of the squid using a moving boundary, thereby capturing the resulting time-dependent flows within the space. By doing so, we can study the impacts on internal flows resulting from variations in the squid’s breathing pattern.