Published online by Cambridge University Press: 01 June 2000
Specimens of Opisthoteuthis grimaldii were video recorded in a shipboard aquarium and their behavioural traits, such as bottom resting, flat-spreading, web-inversion and ballooning response, were described. Ballooning, as defence response, has been recorded only for cirrate octopod families with an intermediate web (Cirroteuthidae: Stauroteuthidae), and this structure has been supposed to be essential for developing this behaviour. Members of the Opisthoteuthidae family lack an intermediate web, indicating that this is a common defence response in cirrates, expressed in a basic form in the Opisthoteuthidae, offering an illustration of how this behaviour can evolve.