21
The swim bladder is the next important organ seen in ray-fi nned fi sh (also
occurring in Sarcopterygii) but not in cartilaginous fi sh. The swim bladder is a sac
containing gas that originally develops as a pouch budding off the embryonic
digestive tract. Because of the presence of this organ, the fi sh is able to adjust its
buoyancy and thus its position in the water column by adjusting the amount of gas
in the swim bladder. It retains an open connection to the esophagus in such fi sh
as sturgeons, gars and eels. However, in most bony fi sh, the swim bladder is completely closed off. This organ is homologous to the lungs of tetrapods because both
develop in the same way. In some fi sh species, especially those with an open swim
bladder, it may be used as a breathing organ too (see for details Harder 1976 ).
The prehistoric looking fi sh “bichir”, or Polypterus, is the most primitive
representative of Actinopterygians of living today (Allis 1922 ). It resembles early
actinopterygians from the Devonian as it has a covering of thick ganoin-based
rhomboidal scales, which are non-overlapping and instead are connected by fi bres.
The skeleton of bichirs is mostly cartilagenous. Eleven species of bichirs habituate
shallow fl oodwater areas in tropical African rivers. Usually, they feed on worms, as
well as on larvae, and imagoes of insects.
Intriguingly, the paired lung-like swim bladders of Polypterus are connected
to the esophagus and correspondingly are used for respiration. The animal is able to
survive for hours out of water.
Order Beloniformes
Some representatives of the order Beloniformes demonstrate how marine bioinspiration
can fi nd applications in aerodynamics and engineering. The fl ying fi sh is a unique
marine fl ying vertebrate. These animals are utilizing the advantages of moving in
two different media, i.e. fl ying in air, as well as swimming in water. The hypertrophied
fi ns and cylindrical body with a ventrally fl attened surface both are good examples
of aerodynamic designs and ideally useful for profi cient gliding fl ight ( Park and
Choi 2010 ). The abrupt transition from predominantly swimming locomotion directly
to fl ight has evolved, for example, in representatives of Exocoetidae. Because of
the exceptional wing design and scaling with regard to fl ight performance, fl ying
fi sh were the objectives of numerous scientifi c studies, which started on the end of
nineteenth century (Ahlborn 1897 ) and were continued at the beginning of twentieth
century (Gill 1905 ; Adams 1906 ; Durnford 1906 ; Shadbolt 1908 ; Crossland 1911 ;
Hubbs 1918 ) and continue to this day (Fish 1990 ; Davenport 1994 , 2003 ; Kutschera
2005 ; Park and Choi 2010 ). The structural specialization of fl ying fi sh from an
aerodynamics standpoint, as well as the source of propulsive power used by these
animals have been of particular interest in previous works (Shoulejkin 1929 ; Breder
1930 ; Forbes 1936 ; Loeb 1936 ; Mills 1936a , b ).
Interestingly, the aerodynamic performance of various forms of bird wings is
comparable to those of fl ying fi sh. Moreover, some morphological characteristics
observed in fl ying fi sh are similar with aerodynamically designed modern aircrafts
(Park and Choi 2010 ). Crucial role play abnormally large pectoral fi ns of the fi sh
that act as airfoils and provide lift when the animal launches itself out of the water
1.2 Part I: Biomaterials of Vertebrate Origin. An Overview
The swim bladder is the next important organ seen in ray-fi nned fi sh (also
occurring in Sarcopterygii) but not in cartilaginous fi sh. The swim bladder is a sac
containing gas that originally develops as a pouch budding off the embryonic
digestive tract. Because of the presence of this organ, the fi sh is able to adjust its
buoyancy and thus its position in the water column by adjusting the amount of gas
in the swim bladder. It retains an open connection to the esophagus in such fi sh
as sturgeons, gars and eels. However, in most bony fi sh, the swim bladder is completely closed off. This organ is homologous to the lungs of tetrapods because both
develop in the same way. In some fi sh species, especially those with an open swim
bladder, it may be used as a breathing organ too (see for details Harder 1976 ).
The prehistoric looking fi sh “bichir”, or Polypterus, is the most primitive
representative of Actinopterygians of living today (Allis 1922 ). It resembles early
actinopterygians from the Devonian as it has a covering of thick ganoin-based
rhomboidal scales, which are non-overlapping and instead are connected by fi bres.
The skeleton of bichirs is mostly cartilagenous. Eleven species of bichirs habituate
shallow fl oodwater areas in tropical African rivers. Usually, they feed on worms, as
well as on larvae, and imagoes of insects.
Intriguingly, the paired lung-like swim bladders of Polypterus are connected
to the esophagus and correspondingly are used for respiration. The animal is able to
survive for hours out of water.
Order Beloniformes
Some representatives of the order Beloniformes demonstrate how marine bioinspiration
can fi nd applications in aerodynamics and engineering. The fl ying fi sh is a unique
marine fl ying vertebrate. These animals are utilizing the advantages of moving in
two different media, i.e. fl ying in air, as well as swimming in water. The hypertrophied
fi ns and cylindrical body with a ventrally fl attened surface both are good examples
of aerodynamic designs and ideally useful for profi cient gliding fl ight ( Park and
Choi 2010 ). The abrupt transition from predominantly swimming locomotion directly
to fl ight has evolved, for example, in representatives of Exocoetidae. Because of
the exceptional wing design and scaling with regard to fl ight performance, fl ying
fi sh were the objectives of numerous scientifi c studies, which started on the end of
nineteenth century (Ahlborn 1897 ) and were continued at the beginning of twentieth
century (Gill 1905 ; Adams 1906 ; Durnford 1906 ; Shadbolt 1908 ; Crossland 1911 ;
Hubbs 1918 ) and continue to this day (Fish 1990 ; Davenport 1994 , 2003 ; Kutschera
2005 ; Park and Choi 2010 ). The structural specialization of fl ying fi sh from an
aerodynamics standpoint, as well as the source of propulsive power used by these
animals have been of particular interest in previous works (Shoulejkin 1929 ; Breder
1930 ; Forbes 1936 ; Loeb 1936 ; Mills 1936a , b ).
Interestingly, the aerodynamic performance of various forms of bird wings is
comparable to those of fl ying fi sh. Moreover, some morphological characteristics
observed in fl ying fi sh are similar with aerodynamically designed modern aircrafts
(Park and Choi 2010 ). Crucial role play abnormally large pectoral fi ns of the fi sh
that act as airfoils and provide lift when the animal launches itself out of the water
1.2 Part I: Biomaterials of Vertebrate Origin. An Overview