Foraging of scavenging deep-sea lysianassoid amphipods

Abstract

Olfaction, possibly combined with a rheotactic swimming behavior, is probably the principal means of detection and localization of bait, but alternative or complementary means have been proposed (territorial collapse, mechanoreception of bait impact on bottom or of sounds of aggregated feeders). Deep-sea, bait-attending lysianassoids seemingly divide into two functional groups. Individuals of the first group (Eurythenes, possibly Paralicella and others) have mandibles and guts modified for rapid and gluttonous feeding, process food in discrete batches, and may survivie long periods without feeding. Individuals of the second group (Orchomene complex) have mandibles which do not appear to be suited for the rapid ingestion of bait, rather small guts, process food in a more or less continuous manner, and may withstand only short periods of starvation. Although lysianassoids in the former group appear to be very well adapted for the detection, localization and consumption of carrion, it seems unlikely that any deep-sea species is an obligate necrophage. The extensive vertical range of deep-sea lysianassoids above bottom indeed suggests that species compensate for deficient bottom resources by foraging in the water column. Deep-sea lysianassoids may be able to sequester carrion from other scavengers. The quantity and quality of carrion or of carrion byproducts (scavenger feces, biomass and offspring) which are passed along to the non-scavenging fauna, as well as the time scale for dispersal of these resources, should largely depend on the kinds of scavengers aggregated to consume bait. -from Author