Mechanoreception for food fall detection in deep sea scavengers

Abstract

Although knowledge about functional principles of deep-sea ecosystems is rather scarce, it is assumed that the energy supply for scavengers is restricted to large food falls of dead vertebrates. It is generally accepted that chemoreception is one of the major tools for marine organisms to detect food sources. However, another major source of information may come from hydroacoustical feeding noises produced by scavengers appearing on a cadaver reached the seafloor. The aim of the present study was to investigate whether scavenging crustaceans—pandalid shrimps Pandalus borealis—are able to detect such rare food fall events via mechanoreception or not. These results are based on 228 single experiments indicating that these animals possess the sensitivity to the particle displacement of 0.1–10 mkm in frequency range 30–250 Hz. Therefore, acoustic feeding noises offer a possibility for animals to detect such rare events but only at distances of a few meters. At such small distances chemoreception is presumably more important. However, based on theoretical calculations on the relevance of various types of waves, originating on the water-sediment interface from any object falling on the seafloor, it is proposed that such ‘‘micro seismic events’’ may allow resting scavengers even some hundred meters away the detection of this event, most likely followed by chemoreceptive tracking.