Noise generated by the jaw actions of feeding fin whales

Abstract

The fin whale (Balaenoptera physalus) is representative of baleen whales, which feed by engulfing up to 70 t of seawater in an elastic throat pouch, prior to filtering. This represents (i) the greatest biomechanical action in the animal kingdom, and (ii) a deviation from the flowthrough design of fishing trawls, most filter-feeders, and sampling devices. Based upon observations of fresh carcasses, it is proposed that during the brief period at full gape agile prey may be startled and retained within the pouch by noise: a synovial joint-crack generated during realignment of the tips of the mandibles. It is argued that the previous detection of nonvocal sounds, attributed to the body movements of feeding fin whales, may also include noise resulting from this action.