The responses of marine invertebrates to changes in hydrostatic pressure within the + 1000 mbar range are reviewed and some response parameters are considered in an attempt to set the phenomenon of barosensitivity in the more general context of animal irritability. Possible mechanisms of transduction are discussed and, in the absence of any identifiable baroreceptor, a comparative psychophysical approach is advocated as a possible means of elucidating further the fundamental properties of such pressure‐sensitive system