179
life threatening conditions such as calculi formation, development of gout or
arteriosclerosis, tissue calcifi cation associated with cancer, etc.,” (Königsberger
and Königsberger 2006 ). In contrast to well investigated pathological biomineralization in humans (see for review Jahnen-Dechent 2004 ; Giachelli 2005 ; Wesson
and Ward 2007 ; Golub 2011 ), the state of the art on pathological biomineralization
in marine vertebrates is on the embryonic stage. Today, we can only suggest that
several cellular components are involved in their pathological mineralization, and
that there is some evidence suggesting pathological mineralization is a regulated
process.
3.8 Silica-Based Minerals in Marine Vertebrates
Abstract Silicon, in the form of silicic acid, is a fundamental nutrient for marine
invertebrates like diatoms, silicofl agellates, radiolaria, and sponges, all of which
polymerize it to build skeletons of biogenic silica. Occurrence of silica-based
minerals in mammals and human is usually determined by pathological processes
like silica urolithiasis. The only example of the presence of silica in the form of
chalcedony that is known is in marine elasmobranch fi sh. Chalcedony is a microfi -
brous (microcrystaline with a fi brous structure) variety of quartz, and was identifi ed
within electric organ of the marine skate Psammobatis extenta.
Silicon dioxide (silica) of biological origin is known as biosilica. It is widely
distributed biomineral in plants and animals and possesses broad variety of morphological forms on nano-, micro- and macroscales. Our interest on silica is based
on the following reasons (Ehrlich et al. 2010 ):
(a) “it is defi nitely the fi rst and the oldest natural bio-skeleton;
(b) it has unique mechanical properties;
(c) it has extremely high specifi c surface area, and, therefore, adsorption properties
for dissolved components in external milieu,” (Ehrlich et al. 2010 ).
Numerous examples of biosilica-based structures observed in both lower and higher
plants, bacteria, yeast, fungi, protists, sponges, molluscs, ascidians, crustaceans,
brachiopods, terrestrial mammals and human are recently discussed (see for review
Ehrlich 2010 , 2011 ).
Reports on silica-containing minerals in marine vertebrates are not common.
Here, I take the liberty to analyse several publications concerning fi ndings of
silica in representatives of Elasmobranchii. I mean the Rajidae family, known
usually as skates (Parago 2001 ). One of the species, the Psammobatis extenta , is
“endemic to the continental shelf of the western South Atlantic, ranging from
Cabo Frio, Rio de Janeiro, Brazil (22°56′S) to Patagonia, Argentina (~45°S),”
(Rocha et al. 2010 ). Surprisingly, the electric organs of this fi sh, which produce
3.8 Silica-Based Minerals in Marine Vertebrates
life threatening conditions such as calculi formation, development of gout or
arteriosclerosis, tissue calcifi cation associated with cancer, etc.,” (Königsberger
and Königsberger 2006 ). In contrast to well investigated pathological biomineralization in humans (see for review Jahnen-Dechent 2004 ; Giachelli 2005 ; Wesson
and Ward 2007 ; Golub 2011 ), the state of the art on pathological biomineralization
in marine vertebrates is on the embryonic stage. Today, we can only suggest that
several cellular components are involved in their pathological mineralization, and
that there is some evidence suggesting pathological mineralization is a regulated
process.
3.8 Silica-Based Minerals in Marine Vertebrates
Abstract Silicon, in the form of silicic acid, is a fundamental nutrient for marine
invertebrates like diatoms, silicofl agellates, radiolaria, and sponges, all of which
polymerize it to build skeletons of biogenic silica. Occurrence of silica-based
minerals in mammals and human is usually determined by pathological processes
like silica urolithiasis. The only example of the presence of silica in the form of
chalcedony that is known is in marine elasmobranch fi sh. Chalcedony is a microfi -
brous (microcrystaline with a fi brous structure) variety of quartz, and was identifi ed
within electric organ of the marine skate Psammobatis extenta.
Silicon dioxide (silica) of biological origin is known as biosilica. It is widely
distributed biomineral in plants and animals and possesses broad variety of morphological forms on nano-, micro- and macroscales. Our interest on silica is based
on the following reasons (Ehrlich et al. 2010 ):
(a) “it is defi nitely the fi rst and the oldest natural bio-skeleton;
(b) it has unique mechanical properties;
(c) it has extremely high specifi c surface area, and, therefore, adsorption properties
for dissolved components in external milieu,” (Ehrlich et al. 2010 ).
Numerous examples of biosilica-based structures observed in both lower and higher
plants, bacteria, yeast, fungi, protists, sponges, molluscs, ascidians, crustaceans,
brachiopods, terrestrial mammals and human are recently discussed (see for review
Ehrlich 2010 , 2011 ).
Reports on silica-containing minerals in marine vertebrates are not common.
Here, I take the liberty to analyse several publications concerning fi ndings of
silica in representatives of Elasmobranchii. I mean the Rajidae family, known
usually as skates (Parago 2001 ). One of the species, the Psammobatis extenta , is
“endemic to the continental shelf of the western South Atlantic, ranging from
Cabo Frio, Rio de Janeiro, Brazil (22°56′S) to Patagonia, Argentina (~45°S),”
(Rocha et al. 2010 ). Surprisingly, the electric organs of this fi sh, which produce
3.8 Silica-Based Minerals in Marine Vertebrates