Relation between red muscle volume and buoyancy of several deep-water sharks
(2018) 3th Sharks International Conference — Location: Joao Pesoa, Bresil (3.June.2018)
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- In opposite with fishes, sharks do not possess swimbladder. Their buoyancy is provided by two features: (i) their liver which is large and rich in low density oil (hydrostatic lift) (ii) the shape of their body and fins which provide a resistive force of water drag (hydrodynamic lift). Despite these, Shallow-water sharks have a negative buoyancy pulling away energy consumption to stay in a same depth. Recent studies suggest that deep-water sharks could be neutral and even positively buoyant. Indeed, results show a larger liver than shallow-water counterparts, richer in oil content with higher level of low density lipids (squalene and DAGE) and low level of high density lipid (TAG). Bone suggested that the red fibers volume in sharks can be correlated to their buoyancy. Several authors have suggested that if the shark is close to neutral buoyancy, we would observe less red fibers as these would take action only in the hydrodynamic lift and not in the hydrostatic lift. Several deep-water sharks perform circadian vertical migration and a neutral buoyancy could allow them to conserve energy in their oligotrophic environment. Here we investigated the buoyancy of three deep-sea species (Etmopterus molleri, Etmopterus spinax, Isitius brasiliensis) and one shallow water counterpart (Galeus melastomus). We used Raman and MIR spectrophotometry to quantify the lipid composition of their liver. We also collected lipid composition data of several other deep-water sharks from the literature and red muscles distribution and volume of ten species were measured to bring in the light the possible correlation between buoyancy and red muscles volume.
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Pinte, N., Godefroid, M., Baeten, V., Ouissam Abbas, Duchatelet, L., & Mallefet, J. (2018). Relation between red muscle volume and buoyancy of several deep-water sharks. 3th Sharks International Conference, Joao Pesoa, Bresil. https://hdl.handle.net/2078.5/56690