Chemical and visual sensory systems in feeding behaviour of the Antarctic fish Ophthalmolycus amberensis (Zoarcidae)

Abstract

The Antarctic eelpout Ophthalmolycus amberensis occurs in Admiralty Bay (King George Island, South Shetlands), at 140-200m depth, where light intensity is low. To assess behavioural and sensory adaptations for feeding under these conditions, laboratory tests were undertaken. Dead krill, fish fillet, and live amphipods were the preferred food items. Feeding responses were mainly induced by chemical stimuli. Visual stimuli were weak elicitors, leading to a long delay in the initiation of feeding behaviour. These fishes present a large olfactory epithelium, a high density of taste buds on the snout and close to the nostrils, and a retina that contained long rods, but no cones. Food selection was observed. Varied types of taste buds were present on the lips and in the oro-pharyngeal cavity. The capacity to use a chemo-sensory system as first elicitor for food detection, either in the absence or presence of light, allows O. amberensis to efficiently exploit different habitats at the sea bottom, in all Antarctic seasons.