The Functional Morphology of the Tentacle Musculature of Nautilus pompilius

Abstract

The morphology of the musculature of cephalopods, and indeed that of many mollusks, is characterized by a tightly packed three-dimensional arrangement of muscle fibers that lack extensive fluid-filled cavities or hardened skeletal elements. Previous research on the arms and tentacles of squids (Kier, 1982) and the arms of octopuses (Kier, 1987) suggests that the skeletal support of these appendages is provided by a type of hydrostatic skeleton that differs from the classic conception of a hydrostatic skeleton (e.g., Chapman, 1958, 1975; Clark, 1964, 1981; Clark and Cowey, 1958; Wainwright, 1970, 1982) in that the musculature both creates movement and provides skeletal support. These appendages, termed muscular-hydrostats, are capable of diverse, complex, and highly controlled movements (Kier and Smith, 1985). This study of the functional morphology of Nautilus tentacles was undertaken to explore further the diversity of muscular arrangement and function in cephalopods.