280
while others oscillate these fi ns ( balistiform ) (Mattheijssens et al. 2012 ). Additionally,
some marine fi sh species are observed that show swimming behaviour that can be
defi ned as “ hydrodynamic parasitism ”, or hitchhiking (Fish 2010 ).
Thus, “hitchhiking is a mechanism to reduce locomotor costs by direct physical
attachment to another animal in motion. As the hitchhiker is passively towed along,
it saves considerable amounts of energy that it would have to expend by muscular
contraction to swim. For this behavior to be of benefi t to the hitchhiker without
being a detriment to the other animal, the hitchhiker must be much smaller in body
size compared to the host animal,” (Fish 2010 ; see also O’Toole 2002 ).
Typical examples are eight species of remoras or sharksuckers ( Echeneididae )
that rely upon hitchhiking. As reviewed by Frank Fish ( 2010 ), “these fi shes attach
onto much larger fi sh, turtles, and whales. Attachment onto large mobile hosts
minimizes the remona’s energy expenditure from locomotion. When attached to a
moving object or in a current, remoras use the water fl ow for respiration, switching
from active branchial ventilation of the gills to passive ram gill ventilation,” (Fish
2010 ; see also Fertl and Landry 1999 ; Guerrero-Ruiz and Urbán 2000 ; Sazima and
Grossman 2006 ; Steffensen and Lomholt 1983 ).
The term BCF imply under body and/or caudal fi n locomotion that is characteristic
for most fi sh species generating thrust by bending their bodies into a backwardmoving propulsive wave that extends to the caudal fi n. There are four undulatory
BCF locomotion modes proposed by their amplitude envelope of the propulsive
wave: anguilliform , subcarangiform , carangiform and thunniform .
They different types are specialized as follows:
Dorsal Fins As described by Suzuki et al. ( 2003 ), “in teleosts, the embryonic fi n
fold consists of a peridermis, an underlying epidermis and a small number of mesenchymal cells. Beginning from such a simple structure, the fi n skeletons, including the
proximal and distal radials and fi nrays, develop in the dorsal fi n fold at the larval
stage. In early larvae the mesenchymal cells grow between the epidermis and spinal
cord to form a line of periodical condensations, which are proximal radial primordia,
to produce chondrocytes. The prescleroblasts, which ossify the proximal radial cartilages, differentiate within the mesenchymal cells remaining between the cartilages.
Then, mesenchymal condensations occur between the distal ends of the proximal
radials, forming distal radial primordia, to produce chondrocytes. Simultaneously,
condensations occur between the distal radial primordia and peridermis, which are
fi nrays primordia, to produce prescleroblasts,” (Suzuki et al. 2003 ).
In adult fi sh, dorsal fi n possesses a unique structure and plays an important role
in their swimming behaviour. According Standen and Lauder ( 2007 ), “recent kinematic and hydrodynamic studies on fi sh median fi ns have shown that dorsal fi ns
actively produce jets with large lateral forces. As the location of dorsal fi ns above
the fi sh’s rolling axis, these lateral forces, if unchecked, would cause fi sh to roll,”
(Standen and Lauder 2007 ).
In some sharks the dorsal fi n shows very specifi c structural properties. As
reported in the paper by Lingham-Soliar ( 2005a ) on examples of several shark
species, “the transverse sections of the skin in the dorsal fi n of the white shark,
7 Fish Fins and Rays as Inspiration for Materials Engineering and Robotics
while others oscillate these fi ns ( balistiform ) (Mattheijssens et al. 2012 ). Additionally,
some marine fi sh species are observed that show swimming behaviour that can be
defi ned as “ hydrodynamic parasitism ”, or hitchhiking (Fish 2010 ).
Thus, “hitchhiking is a mechanism to reduce locomotor costs by direct physical
attachment to another animal in motion. As the hitchhiker is passively towed along,
it saves considerable amounts of energy that it would have to expend by muscular
contraction to swim. For this behavior to be of benefi t to the hitchhiker without
being a detriment to the other animal, the hitchhiker must be much smaller in body
size compared to the host animal,” (Fish 2010 ; see also O’Toole 2002 ).
Typical examples are eight species of remoras or sharksuckers ( Echeneididae )
that rely upon hitchhiking. As reviewed by Frank Fish ( 2010 ), “these fi shes attach
onto much larger fi sh, turtles, and whales. Attachment onto large mobile hosts
minimizes the remona’s energy expenditure from locomotion. When attached to a
moving object or in a current, remoras use the water fl ow for respiration, switching
from active branchial ventilation of the gills to passive ram gill ventilation,” (Fish
2010 ; see also Fertl and Landry 1999 ; Guerrero-Ruiz and Urbán 2000 ; Sazima and
Grossman 2006 ; Steffensen and Lomholt 1983 ).
The term BCF imply under body and/or caudal fi n locomotion that is characteristic
for most fi sh species generating thrust by bending their bodies into a backwardmoving propulsive wave that extends to the caudal fi n. There are four undulatory
BCF locomotion modes proposed by their amplitude envelope of the propulsive
wave: anguilliform , subcarangiform , carangiform and thunniform .
They different types are specialized as follows:
Dorsal Fins As described by Suzuki et al. ( 2003 ), “in teleosts, the embryonic fi n
fold consists of a peridermis, an underlying epidermis and a small number of mesenchymal cells. Beginning from such a simple structure, the fi n skeletons, including the
proximal and distal radials and fi nrays, develop in the dorsal fi n fold at the larval
stage. In early larvae the mesenchymal cells grow between the epidermis and spinal
cord to form a line of periodical condensations, which are proximal radial primordia,
to produce chondrocytes. The prescleroblasts, which ossify the proximal radial cartilages, differentiate within the mesenchymal cells remaining between the cartilages.
Then, mesenchymal condensations occur between the distal ends of the proximal
radials, forming distal radial primordia, to produce chondrocytes. Simultaneously,
condensations occur between the distal radial primordia and peridermis, which are
fi nrays primordia, to produce prescleroblasts,” (Suzuki et al. 2003 ).
In adult fi sh, dorsal fi n possesses a unique structure and plays an important role
in their swimming behaviour. According Standen and Lauder ( 2007 ), “recent kinematic and hydrodynamic studies on fi sh median fi ns have shown that dorsal fi ns
actively produce jets with large lateral forces. As the location of dorsal fi ns above
the fi sh’s rolling axis, these lateral forces, if unchecked, would cause fi sh to roll,”
(Standen and Lauder 2007 ).
In some sharks the dorsal fi n shows very specifi c structural properties. As
reported in the paper by Lingham-Soliar ( 2005a ) on examples of several shark
species, “the transverse sections of the skin in the dorsal fi n of the white shark,
7 Fish Fins and Rays as Inspiration for Materials Engineering and Robotics