164
3.5.5 Conclusion
There are no doubts, that numerous behavioral experiments that have been carried
out during last decades (for review see Eder et al. 2012 ) give us evidence for the
existence of a magnetic sense in the animal’s world, including representatives of
marine fauna. According to Joseph Kirschvink, “all matrix-mediated biomineral
systems in higher animals could have evolved from the magnetite system during the
Cambrian explosion” (Kirschvink et al. 2001 ; see also Kirschvink and Hagadorn
2000 ). Today, only the light-dependent and magnetite-based magnetoreception
theories are accepted as those which try to explain the phenomenon to detect
Earth- strength magnetic fi elds by living organisms. Further progress requires
development of procedures that will distinguish between magnetic contaminants
and biologic precipitates in tissue. Very recently, Michael Winklhofer and co-workers
represented an effective approach how to isolate and to characterize potential
magnetite- based magnetoreceptor cells from the trout olfactory epithelium (Eder
et al. 2012 b). They used confocal refl ectance imaging, that allow to visualize a
μm-sized intracellular structures of iron-rich crystals as bright refl ective spots localized close to the cell membrane. These authors summarized that “the magnetic
inclusions are found to be fi rmly coupled to the cell membrane, enabling a direct
transduction of mechanical stress produced by magnetic torque acting on the
cellular dipole in situ. These specialized cells clearly meet the physical requirements for a magnetoreceptor capable of rapidly detecting small changes in the
external magnetic fi eld,” (Eder et al. 2012 ).
3.6 Biohalite
Abstract Cranial exocrine formations that secrete hyperosmotic electrolyte solutions
are known as salt glands. They supplement renal ion excretion in some nonmammalian vertebrates. NaCl is the main component of the secreted electrolytes in most
animals including sear birds and sea reptiles. The secretory epithelium of salt glands
contains salt secreting principal cells. In this chapter, I take the liberty to introduce the
new term “ biohalite ” for the NaCl-based biomineral originating from the salt glands.
Halite, the natural form of salt (NaCl), is a very common and well-known mineral
(Finger and King 1978 ). It is found in solid masses, and as a dissolved solution in
the oceans and salt lakes. However, marine vertebrates including fi sh, reptiles and
birds possess unique organs, the salt glands, which are responsible for production of
NaCl. Moreover, they are “able to produce a highly concentrated salt solution, making
it possible to tolerate drinking sea water,” (Schmidt-Nielsen and Fange 1958a ).
Schmidt-Nielsen and Fänge ( 1958b ) discovered this phenomenon. The physiology
of salt glands in numerous representatives of tetrapod and elasmobranch fi sh (Fänge
and Fugelli 1962 ) with respect to better understanding of the principal mechanisms by
3 Biocomposites and Mineralized Tissues
3.5.5 Conclusion
There are no doubts, that numerous behavioral experiments that have been carried
out during last decades (for review see Eder et al. 2012 ) give us evidence for the
existence of a magnetic sense in the animal’s world, including representatives of
marine fauna. According to Joseph Kirschvink, “all matrix-mediated biomineral
systems in higher animals could have evolved from the magnetite system during the
Cambrian explosion” (Kirschvink et al. 2001 ; see also Kirschvink and Hagadorn
2000 ). Today, only the light-dependent and magnetite-based magnetoreception
theories are accepted as those which try to explain the phenomenon to detect
Earth- strength magnetic fi elds by living organisms. Further progress requires
development of procedures that will distinguish between magnetic contaminants
and biologic precipitates in tissue. Very recently, Michael Winklhofer and co-workers
represented an effective approach how to isolate and to characterize potential
magnetite- based magnetoreceptor cells from the trout olfactory epithelium (Eder
et al. 2012 b). They used confocal refl ectance imaging, that allow to visualize a
μm-sized intracellular structures of iron-rich crystals as bright refl ective spots localized close to the cell membrane. These authors summarized that “the magnetic
inclusions are found to be fi rmly coupled to the cell membrane, enabling a direct
transduction of mechanical stress produced by magnetic torque acting on the
cellular dipole in situ. These specialized cells clearly meet the physical requirements for a magnetoreceptor capable of rapidly detecting small changes in the
external magnetic fi eld,” (Eder et al. 2012 ).
3.6 Biohalite
Abstract Cranial exocrine formations that secrete hyperosmotic electrolyte solutions
are known as salt glands. They supplement renal ion excretion in some nonmammalian vertebrates. NaCl is the main component of the secreted electrolytes in most
animals including sear birds and sea reptiles. The secretory epithelium of salt glands
contains salt secreting principal cells. In this chapter, I take the liberty to introduce the
new term “ biohalite ” for the NaCl-based biomineral originating from the salt glands.
Halite, the natural form of salt (NaCl), is a very common and well-known mineral
(Finger and King 1978 ). It is found in solid masses, and as a dissolved solution in
the oceans and salt lakes. However, marine vertebrates including fi sh, reptiles and
birds possess unique organs, the salt glands, which are responsible for production of
NaCl. Moreover, they are “able to produce a highly concentrated salt solution, making
it possible to tolerate drinking sea water,” (Schmidt-Nielsen and Fange 1958a ).
Schmidt-Nielsen and Fänge ( 1958b ) discovered this phenomenon. The physiology
of salt glands in numerous representatives of tetrapod and elasmobranch fi sh (Fänge
and Fugelli 1962 ) with respect to better understanding of the principal mechanisms by
3 Biocomposites and Mineralized Tissues