Can squid really hear? Behavior, directional responses and hearing diversity in cephalopods

Aran T. Mooney, WHOI, Biology
R. I. Ruiz-Cooley, Protected Resources Division, Southwest Fisheries Science Center, National Marine Fisheries, NOAA
Pedro Afonso, Department of Fisheries and Oceans, University of the Azores


Project Summary

Hearing is a key sense for many marine animals and is fundamental to many critical
vertebrate and invertebrate behaviors. Yet, there has been little investigation of hearing or sound responses in most marine invertebrates. It is particularly surprising that there are few studies of hearing for cephalopods (octopus, squid, cuttlefish, nautilus) since they have sophisticated behaviors, are a significant component of the ocean’s biomass, and play a critical role in food webs from diverse ecosystems. My recent work demonstrated that sounds stimulate physiological ‘auditory’ responses in one squid species, Loligo pealeii, providing the first strong evidence that squid can hear. This is a previously unsupported sensory modality which may influence squid population dynamics, evolution and fisheries interactions. Despite physiological responses, it is unclear how squid may use sound, if they behaviorally respond, and whether this sensory modality occurs in other species. Addressing these questions is necessary to understand the function and importance of hearing in this crucial marine invertebrate.

This work proposes to test the functional use of sound and its broader relevance as a sensory cue. A simple behavioral assay will examine whether squid actually respond to sound and physiological measurements will address the directionality of squid hearing. Additionally, comparative field recordings of physiological responses in two new species will test whether this sensory modality is found in additional taxa. Hearing tests in new species will involve two species of commercial interest, important trophic constituents and inhabitants of dark pelagic waters where sound may be an especially important cue: Dosidicus gigas (jumbo Humboldt squid, the largest and most aggressive species of the Ommastrephidae family) and L. forbesi (the largest species of the Loliginidae family). This work seeks to understand the functional importance of an overlooked sensory modality in a key invertebrate group, thus exploring sensory diversity, our understanding of ecological relationships and potential measures for fisheries and conservation of harvested squid. In doing so, we directly address OLI’s themes of Ocean biodiversity and Ocean megafuana. These experiments will be an exceptional opportunity to build upon recent achievements, enhance capabilities to acquire future support, advance the career of a new Assistant Scientist, build new collaborations, and broaden WHOI’s novel research base toward investigating the sensory systems of another class of marine animals (invertebrates), of which squid represent a keystone and model species.