287
6. Trout anal fi n function differs from dorsal fi n function; although dorsal and anal
fi ns appear to cooperate functionally, there are complex interactions between
other fi ns and free stream perturbations that require independent dorsal and anal
fi n motion and torque production to maintain control of body position,” (Standen
and Lauder 2007 ).
Propulsion in some fi sh species is based on function of the long anal fi ns that are
moved in an undulating manner (Snyder et al. 2007 ). For example, Amazonian
black ghost knifefi sh ( Apteronotus albifrons ) possess characteristic elongated
ribbon- like anal fi n, the structure that is used due to its primary propulsive mechanism. As described by Shirgaonkar et al. ( 2008 ), “knifefi sh continuously emit a
weak electric fi eld, which is perturbed by objects that enter the fi eld and distort the
fi eld because their electrical properties differ from the surrounding fl uid. These perturbations are detected by thousands of electroreceptors on the surface of the
body. MacIver and coworkers have shown that the knifefi sh is able to both sense
and move omnidirectionally,” (Shirgaonkar et al. 2008 ; see also Snyder et al. 2007 ).
Furthermore, “they swim forward by sending undulations along the ribbon fi n in the
anterior to posterior direction. They can easily swim backward by reversing the
direction of the traveling waves, and can move vertically by simultaneously sending
traveling waves from the head and tail toward the center of the fi n. This cancels
longitudinal forces and amplifi es the vertical force,” (Curet et al. 2011a ). These fi sh
showed different maneuvers including rapid body rolls (MacIver et al. 2001 ), and
even omnidirectional moving over short time intervals (Snyder et al. 2007 ).
The ability of this fi sh to switch movement direction rapidly (in ≈100 ms)
(MacIver et al. 2001 ), inspired numerous experiments with the goal of developing a
similar robotic device (Curet et al. 2011a , b ) (Fig. 7.4 ).
In addition to swimming, there are other roles for the anal fi n in fi sh. The anal fi n
in some fi sh like Japanese medaka ( Oryzias latipes ), is a typical sexual secondary
Fig. 7.4 The south american knifefi sh ( Apteronotus albifrons ) ( a , Image courtesy of Per Erik
Sviland) and its bioinspired robotic implementation ( b , Reprinted from Curet et al. ( 2011b ). © IOP
Publishing. Reproduced with permission. All rights reserved)
7.1 Fish Fins and Rays: Diversity, Structure and Function
6. Trout anal fi n function differs from dorsal fi n function; although dorsal and anal
fi ns appear to cooperate functionally, there are complex interactions between
other fi ns and free stream perturbations that require independent dorsal and anal
fi n motion and torque production to maintain control of body position,” (Standen
and Lauder 2007 ).
Propulsion in some fi sh species is based on function of the long anal fi ns that are
moved in an undulating manner (Snyder et al. 2007 ). For example, Amazonian
black ghost knifefi sh ( Apteronotus albifrons ) possess characteristic elongated
ribbon- like anal fi n, the structure that is used due to its primary propulsive mechanism. As described by Shirgaonkar et al. ( 2008 ), “knifefi sh continuously emit a
weak electric fi eld, which is perturbed by objects that enter the fi eld and distort the
fi eld because their electrical properties differ from the surrounding fl uid. These perturbations are detected by thousands of electroreceptors on the surface of the
body. MacIver and coworkers have shown that the knifefi sh is able to both sense
and move omnidirectionally,” (Shirgaonkar et al. 2008 ; see also Snyder et al. 2007 ).
Furthermore, “they swim forward by sending undulations along the ribbon fi n in the
anterior to posterior direction. They can easily swim backward by reversing the
direction of the traveling waves, and can move vertically by simultaneously sending
traveling waves from the head and tail toward the center of the fi n. This cancels
longitudinal forces and amplifi es the vertical force,” (Curet et al. 2011a ). These fi sh
showed different maneuvers including rapid body rolls (MacIver et al. 2001 ), and
even omnidirectional moving over short time intervals (Snyder et al. 2007 ).
The ability of this fi sh to switch movement direction rapidly (in ≈100 ms)
(MacIver et al. 2001 ), inspired numerous experiments with the goal of developing a
similar robotic device (Curet et al. 2011a , b ) (Fig. 7.4 ).
In addition to swimming, there are other roles for the anal fi n in fi sh. The anal fi n
in some fi sh like Japanese medaka ( Oryzias latipes ), is a typical sexual secondary
Fig. 7.4 The south american knifefi sh ( Apteronotus albifrons ) ( a , Image courtesy of Per Erik
Sviland) and its bioinspired robotic implementation ( b , Reprinted from Curet et al. ( 2011b ). © IOP
Publishing. Reproduced with permission. All rights reserved)
7.1 Fish Fins and Rays: Diversity, Structure and Function