281
Carcharodon carcharias , tiger shark, Galeocerdo cuvier , and spotted raggedtooth
shark, Carcharias taurus , show large numbers of dermal fi ber bundles, which
extend from the body into the fi n. The bundles are tightly grouped together in a
staggered formation (not arranged in a straight line or in rows). This arrangement of
dermal fi bers gives tensile strength without impeding fi ber movement. Tangential
sections indicate that the fi bers in all three species are strained and lie at angles in
excess of 60°. The overall results indicate that the dorsal fi n of C. carcharias functions as a dynamic stabilizer and that the dermal fi bers are crucial to this role. The
fi bers work like riggings that stabilize a ship’s mast. During fast swimming, when
the problems of yaw and roll are greatest, hydrostatic pressure within the shark
increases and the fi bers around the body, including in the dorsal fi n, become taut,
thereby stiffening the fi n. During slow swimming and feeding the hydrostatic pressure is reduced, the fi bers are slackened, and the muscles are able to exert greater
bending forces on the fi n via the radials and ceratotrichia. In C. carcharias there is
a trade-off for greater stiffness in the dorsal fi n versus that of fl exibility,” (LinghamSoliar 2005a ).
Caudal Fin The role of caudal fi n in the swimming and propulsion of some fi sh
was excellently described by Bainbridge ( 1963 ). During steady, fairly fast, straight
locomotion, forward progression is effected entirely by lateral movements of the
body and the caudal fi n. Dependent to a certain extent on the forward velocity,
the paired pectoral and pelvic fi ns and the dorsal fi n are usually closely pressed to
the body. The median anal fi n remains more or less extended during this type of
swimming, but its propulsive signifi cance cannot be very great. As the velocity
gradually diminishes, the dorsal fi n and then the paired fi ns start to rise from the
body. The lateral propulsive movements of the body are in the form of a wave which
travels, with increasing amplitude, from the front end of the body to the rear. The
amplitude is at a maximum at the most posterior edge of the caudal fi n. It was
concluded (Bainbridge 1963 ) that the fi sh has active control over the speed, and
the amount of bending and area of the caudal fi n during transverse movement. The
current though is that (Esposito et al. 2012 ) in many fi sh the caudal fi n is used not
exclusively for thrust production, but also functions to create forces and moments
that control the orientation of the fi sh. These occur via complex conformational
changes and motions. These shape changes and kinematic patterns are produced by
fi n rays within the caudal fi n. The rays are moved by intrinsic caudal musculature
that is distinct from the segmented body muscles (see Fig. 7.2 ).
The importance of caudal locomotion has been highlighted by George Lauder
( 1989 ) in his famous review paper entitled “ Caudal Fin Locomotion in Ray - fi nned
Fishes : Historical and Functional Analyses ”. It was suggested that “the perfection
of caudal locomotion has probably been the single greatest achievement of the teleostean fi shes,” (Lauder 1989 ; see also Gosline 1971 ). The morphology of form
and shape seen in caudal fi ns between different fi sh lineages is quite diverse. “The
tail of Polypterus, the most primitive living actinopterygian (Fig. 7.2 ), is specialized
compared to other lower ray-fi nned fi shes in that it has a diphycercal morphology.
Dissections of Polypterus reveal that the lateral myotomes thin in a posterior direction
7.1 Fish Fins and Rays: Diversity, Structure and Function
Carcharodon carcharias , tiger shark, Galeocerdo cuvier , and spotted raggedtooth
shark, Carcharias taurus , show large numbers of dermal fi ber bundles, which
extend from the body into the fi n. The bundles are tightly grouped together in a
staggered formation (not arranged in a straight line or in rows). This arrangement of
dermal fi bers gives tensile strength without impeding fi ber movement. Tangential
sections indicate that the fi bers in all three species are strained and lie at angles in
excess of 60°. The overall results indicate that the dorsal fi n of C. carcharias functions as a dynamic stabilizer and that the dermal fi bers are crucial to this role. The
fi bers work like riggings that stabilize a ship’s mast. During fast swimming, when
the problems of yaw and roll are greatest, hydrostatic pressure within the shark
increases and the fi bers around the body, including in the dorsal fi n, become taut,
thereby stiffening the fi n. During slow swimming and feeding the hydrostatic pressure is reduced, the fi bers are slackened, and the muscles are able to exert greater
bending forces on the fi n via the radials and ceratotrichia. In C. carcharias there is
a trade-off for greater stiffness in the dorsal fi n versus that of fl exibility,” (LinghamSoliar 2005a ).
Caudal Fin The role of caudal fi n in the swimming and propulsion of some fi sh
was excellently described by Bainbridge ( 1963 ). During steady, fairly fast, straight
locomotion, forward progression is effected entirely by lateral movements of the
body and the caudal fi n. Dependent to a certain extent on the forward velocity,
the paired pectoral and pelvic fi ns and the dorsal fi n are usually closely pressed to
the body. The median anal fi n remains more or less extended during this type of
swimming, but its propulsive signifi cance cannot be very great. As the velocity
gradually diminishes, the dorsal fi n and then the paired fi ns start to rise from the
body. The lateral propulsive movements of the body are in the form of a wave which
travels, with increasing amplitude, from the front end of the body to the rear. The
amplitude is at a maximum at the most posterior edge of the caudal fi n. It was
concluded (Bainbridge 1963 ) that the fi sh has active control over the speed, and
the amount of bending and area of the caudal fi n during transverse movement. The
current though is that (Esposito et al. 2012 ) in many fi sh the caudal fi n is used not
exclusively for thrust production, but also functions to create forces and moments
that control the orientation of the fi sh. These occur via complex conformational
changes and motions. These shape changes and kinematic patterns are produced by
fi n rays within the caudal fi n. The rays are moved by intrinsic caudal musculature
that is distinct from the segmented body muscles (see Fig. 7.2 ).
The importance of caudal locomotion has been highlighted by George Lauder
( 1989 ) in his famous review paper entitled “ Caudal Fin Locomotion in Ray - fi nned
Fishes : Historical and Functional Analyses ”. It was suggested that “the perfection
of caudal locomotion has probably been the single greatest achievement of the teleostean fi shes,” (Lauder 1989 ; see also Gosline 1971 ). The morphology of form
and shape seen in caudal fi ns between different fi sh lineages is quite diverse. “The
tail of Polypterus, the most primitive living actinopterygian (Fig. 7.2 ), is specialized
compared to other lower ray-fi nned fi shes in that it has a diphycercal morphology.
Dissections of Polypterus reveal that the lateral myotomes thin in a posterior direction
7.1 Fish Fins and Rays: Diversity, Structure and Function