Behavioural aspects of the spotty bobtail squid Euprymna parva (Cephalopoda: Sepiolidae)

Bobtail squids (Sepiolidae, Cephalopoda) have recently been growing in popularity in scientific studies due to their symbiotic relationship with light producing bacteria and their corresponding light emitting organs. However, the overall knowledge on the behaviour of sepiolids is based on observations on just a few of the roughly 70 extant species and must still be considered as sparsely. Understanding their behavioural ecology is not only beneficial to further grasp the complex behavioural patterns of cephalopods, it is also vital for establishing a good welfare practice when holding sepiolids in captivity. Hence, the present study characterised several behavioural aspects of the spotty bobtail squid Euprymna parva. Although the burying, hunting and mating behaviour as well as most escape responses of this less investigated sepiolid species greatly resembled those of other observed bobtail squids, differences to sepiolids from other genera or even from the same genus could be identified in the present study. Additionally, the first observation of an up to now undescribed inking behaviour of sepiolids is reported. E. parva was observed to eject a stretch of ink (‘ink rope’), approximately 4–5 times the length of the animal, and hold on to it motionless, potentially as a masquerade to resemble a floating seagrass leave. The present study further provides detailed information on daily time and activity budgets as well as the tentacular strike speed during hunting, two up to now barely investigated behavioural aspects of the sepiolid ecology