The secret life of the giant Australian cuttlefish Sepia apama (Cephalopoda): Behaviour and energetics in nature revealed through radio acoustic positioning and telemetry (RAPT)

Abstract

Sepia apama were tagged with acoustic transmitters and monitored on their native House Reef, Boston Bay, South Australia, with a radio acoustic positioning telemetry (RAPT) system. Cuttlefish were tagged with position-only and intra-mantle jet pressure transmitters. New data analyses were developed to handle problem data that arise with an uneven reef environment. Maximum range for the cuttlefish varied from 90 m to 550 m. Cuttlefish home range was between 5300 m 2 and 23,700 m 2. S. apama were found to be diurnal as average distance travelled was higher in the day than at night, and cuttlefish were active for 32 days, but only 18 nights. After the cuttlefish settled into reef crevices, activity spectrum and positioning analysis showed foraging behaviour at only 3.7% per day and 2.1% per night. Cuttlefish were found to spend more than 95% of the day resting, which suggests that their bioenergetics are more akin to those of octopus than of squid. The cuttlefish combination of predator avoidance, efficient foraging and quiescent lifestyle allows energy to be channelled into growth and fulfillment of the live-fast-die-young cephalopod philosophy.