Bone structure of some marine vertebrates

Bone tissue and bone organ densities, and major components of bone (i.e., ash, organic+CO₂, water and fat) of sperm whale, fin whale, sea lion, albacore, mackerel, rattail and guitarfish were measured. Mammalian vertebrae have higher tissue densities and lower organ densities than fishes. This is because of the high ash and organic content of the bone tissue and the large interstitial volume of the bone organ of mammals. Only albacore and mackerel vertebrae, which had the highest organ densities, and fin whale rib, which had the lowest organ density, contained appreciable quantities of fats. Hydrated tissue densities of all the vertebrates studies are directly correlated with ash content and inversely correlated with water content. Bone structure as related to buoyancy and locomotion is also discussed.