78
The nurse shark, the bamboo shark as well as the cookie-cutter shark, are not only
suction specialists, they also possess stiffest ceratohyals. Nurse sharks and bamboo
sharks ( Chiloscyllium plagiosum ) can generate among the greatest recorded subambient
suction pressures when feeding (Motta et al. 2008 ; Wilga and Sanford 2008 ). The
feeding behaviour of the cookie-cutter shark ( Isistius brasiliensis ) is described as
follow: this predator “remove a plug of fl esh from the body of a cetaceans or some
large fi sh with strong suction pressure after cutting the fl esh using its razor-shaped
lower teeth,” (Tomita et al. 2011 ; see for more information Shirai and Nakaya 1992 ).
The zebra shark ( Stegostoma fasciatum ) and the nurse shark ( G. cirratum ) are known
suction capture small bony fi shes as well as suck out the soft parts of molluscs like
moon shells or trumpet shells from their hard mineralized encasements. It was
reported about large amounts of moon shell opercula that have been found in the
gastric contents of S. fasciatum (Tomita et al. 2011 ).
Giant whale sharks (for example, the Rhincodon typus ) are the biggest fi sh in the
ocean (Gudger 1941 ), and, correspondingly, possess skeletons which are many
times larger than those of the largest bony fi sh. It was reported that “shark skeletons
endure tens to hundreds of millions of loading cycles in their transoceanic migrations,” (Porter et al. 2006 ; see also Bonfi l et al. 2005 ). It was supposed (Porter et al.
2006 ) that in some sharks, “the skeleton must resist the high loads that occur during
burst swimming,” (Porter et al. 2006 ). These authors investigated both the biochemistry and the material properties of the mineralized cartilage found in the vertebrae
of selected elasmobranch species. Similarity with respect to ultimate strength and
material stiffness has been observed between mammalian trabecular bone and calcifi ed cartilage of Elasmobranchii studied. It was shown that the “collagen contents
are more similar to mammalian bone than to mammalian cartilage, and these vertebrae have mineral fractions equalling that of mammalian bone” (Porter et al. 2006 ).
Moreover, “that vertebral cartilage has bone-like stiffness and strength makes it
unlikely that decreased functional demands were a selective force in the abandonment of a bony skeleton by cartilaginous fi shes,” (Porter et al. 2006 ).
The functional stiffness of articular cartilage is |E*|, the dynamic elastic modulus, as explained in Fig. 2.4 . |E*| is a function of the rate of deformation and can be
determined from cyclic load/displacement data (Loparic et al. 2010 ). The rate
employed should refl ect the transient loading-unloading time of normal ambulation
(i.e., running or walking). In humans, this is in the range of a few hundred milliseconds. Therefore, the authors performed indentation measurements at a rate of three
complete loading/unloading cycles per second, corresponding to a tip unloading
time of ~150 ms. Even after hundreds of loading/unloading cycles, they did not
observe any progressive change in the load/displacement behavior, persistent residual indentations (which would be indicative of yield and plastic fl ow), or effects
indicative of material fatigue.
Very interesting results were recently reported by Adam Summers (Macesic and
Summers 2012 ). He and co-workers investigated a batoid (skate and ray) appendicular skeletal element, the propterygium, and its response to forces experienced
during punting (benthic pelvic fi n locomotion). The goals for their study were to
2 Cartilage of Marine Vertebrates
The nurse shark, the bamboo shark as well as the cookie-cutter shark, are not only
suction specialists, they also possess stiffest ceratohyals. Nurse sharks and bamboo
sharks ( Chiloscyllium plagiosum ) can generate among the greatest recorded subambient
suction pressures when feeding (Motta et al. 2008 ; Wilga and Sanford 2008 ). The
feeding behaviour of the cookie-cutter shark ( Isistius brasiliensis ) is described as
follow: this predator “remove a plug of fl esh from the body of a cetaceans or some
large fi sh with strong suction pressure after cutting the fl esh using its razor-shaped
lower teeth,” (Tomita et al. 2011 ; see for more information Shirai and Nakaya 1992 ).
The zebra shark ( Stegostoma fasciatum ) and the nurse shark ( G. cirratum ) are known
suction capture small bony fi shes as well as suck out the soft parts of molluscs like
moon shells or trumpet shells from their hard mineralized encasements. It was
reported about large amounts of moon shell opercula that have been found in the
gastric contents of S. fasciatum (Tomita et al. 2011 ).
Giant whale sharks (for example, the Rhincodon typus ) are the biggest fi sh in the
ocean (Gudger 1941 ), and, correspondingly, possess skeletons which are many
times larger than those of the largest bony fi sh. It was reported that “shark skeletons
endure tens to hundreds of millions of loading cycles in their transoceanic migrations,” (Porter et al. 2006 ; see also Bonfi l et al. 2005 ). It was supposed (Porter et al.
2006 ) that in some sharks, “the skeleton must resist the high loads that occur during
burst swimming,” (Porter et al. 2006 ). These authors investigated both the biochemistry and the material properties of the mineralized cartilage found in the vertebrae
of selected elasmobranch species. Similarity with respect to ultimate strength and
material stiffness has been observed between mammalian trabecular bone and calcifi ed cartilage of Elasmobranchii studied. It was shown that the “collagen contents
are more similar to mammalian bone than to mammalian cartilage, and these vertebrae have mineral fractions equalling that of mammalian bone” (Porter et al. 2006 ).
Moreover, “that vertebral cartilage has bone-like stiffness and strength makes it
unlikely that decreased functional demands were a selective force in the abandonment of a bony skeleton by cartilaginous fi shes,” (Porter et al. 2006 ).
The functional stiffness of articular cartilage is |E*|, the dynamic elastic modulus, as explained in Fig. 2.4 . |E*| is a function of the rate of deformation and can be
determined from cyclic load/displacement data (Loparic et al. 2010 ). The rate
employed should refl ect the transient loading-unloading time of normal ambulation
(i.e., running or walking). In humans, this is in the range of a few hundred milliseconds. Therefore, the authors performed indentation measurements at a rate of three
complete loading/unloading cycles per second, corresponding to a tip unloading
time of ~150 ms. Even after hundreds of loading/unloading cycles, they did not
observe any progressive change in the load/displacement behavior, persistent residual indentations (which would be indicative of yield and plastic fl ow), or effects
indicative of material fatigue.
Very interesting results were recently reported by Adam Summers (Macesic and
Summers 2012 ). He and co-workers investigated a batoid (skate and ray) appendicular skeletal element, the propterygium, and its response to forces experienced
during punting (benthic pelvic fi n locomotion). The goals for their study were to
2 Cartilage of Marine Vertebrates