Preliminary report of specific behaviours of juvenile greater blue-ringed octopus Hapalochlaena lunulata (Quoy and Gaimard, 1832)

Abstract

ABSTRACTThe greater blue-ringed octopus (Hapalochlaena lunulata) is one of three venomous octopuses well-known for the iridescent blue rings on the skin and dangerous toxin. However, the understanding of this octopus at the juvenile phase is limited compared to the adult phase. The other two venomous octopuses (Hapalochlaena fasciata and Hapalochlaena maculosa) have also not been thoroughly examined at the juvenile stage. We collected a juvenile greater blue-ringed octopus from the coastal waters of the Ryukyu Archipelago, Japan, and maintained it in captivity for observation. Five days after beginning rearing, iridescent blue rings, similar to those in the adult, appeared on the entire skin of the octopus and continued to be expressed with varying intensity. When the octopus was behaving aggressively it flashed the blue rings. Episodic antagonistic behaviour against the experimenters was also observed.