426
However, my interest is based on the high structural similarity between these gill
rackers and those of whale baleen. Intriguingly, our fi rst measurements on mechanical properties of both biological materials showed very similar results. Now, we are
starting experimental work to investigate the chemical composition of gill rackers
from whale sharks. It would be very surprising to obtain analytical results confi rming the keratinous nature of these gill rackers, as sharks and whales are related to
fi sh and mammals, respectively. This challenging and exciting task stimulates our
attempts to obtain new knowledge.
Amphibian Skin Desalination or other water purifi cation by use of membranes
are topics of much current interest. The skin of amphibians seems to be the source
of bioinspiration for this application. Both phenomena, which player crucial role
in amphibian evolution, like gas exchange and free water movement across skin
are based on specifi c permeability of their skin. “Amphibians generally have very
high rates of water turnover unless, like fossorial forms, they exploit environmental situations where water fl uxes across their highly permeable skins are low.
Many amphibians have remarkable tolerances to osmotic imbalances, and are able
to rectify these rapidly when water becomes available,” (Shoemaker and Nagy
1977 ; see also Neill 1958 ). Salinity potentially infl uences the abundance and
distribution of amphibians by imposing osmotic stress (Smith et al. 2007 ). The
issue of salinity effects on amphibian biology and ecology has recently drawn
more attention, for at least two reasons (see for review Wu and Kam 2009 ): fi rst,
several studies have revealed that amphibians breed in brackish water more
commonly than originally thought, and that they exhibit interesting physiological
and ecological adjustments to increased salinity stress; second, amphibians are
important indicator species for freshwater ecosystems that face increased
salinization due to natural causes, or to anthropogenic ones such as salt pollution
resulting from road de-icing salt runoff.
In contrast to amphibians, reptiles, due to their low skin permeability, uricotelism, and salt glands, are well adapted to remain in water. Amphibians adapted to
saline media store solutes and remain at least slightly hyperosmotic to their environment (see for review Schoemaker and Nagy 1977 ).
As discussed by Natchev and co-authors:
“Due to their highly vascularised and permeable skins, amphibians have a low
capacity to handle increased salinity in the waters they inhabit. Nevertheless, a
few species are able to live in brackish and even hypersaline waters. Reports on
adult amphibians, as well as their tadpoles, living under saline conditions are
numerous; but only a few amphibians can survive prolonged exposure to sea
water. Among anuran species, adaptations to elevated salinity differ considerably. One ranid species – the crab eating frog, Fejervarya cancrivora (Gravenhorst
1829) – is considered to possess the highest salinity tolerance among amphibians. In this species, 50 % of the larvae survived in up to 80 % sea water – equivalent to 0.5 %M Cl,” (Natchev et al. 2011 ; see also Beebee 1985 ; Dunson 1977 ;
Karraker 2007 ; Sillero and Ribeiro 2010 ; Spotila and Berman 1976 ; Wu and
Kam 2009 ).
14 Epilogue
However, my interest is based on the high structural similarity between these gill
rackers and those of whale baleen. Intriguingly, our fi rst measurements on mechanical properties of both biological materials showed very similar results. Now, we are
starting experimental work to investigate the chemical composition of gill rackers
from whale sharks. It would be very surprising to obtain analytical results confi rming the keratinous nature of these gill rackers, as sharks and whales are related to
fi sh and mammals, respectively. This challenging and exciting task stimulates our
attempts to obtain new knowledge.
Amphibian Skin Desalination or other water purifi cation by use of membranes
are topics of much current interest. The skin of amphibians seems to be the source
of bioinspiration for this application. Both phenomena, which player crucial role
in amphibian evolution, like gas exchange and free water movement across skin
are based on specifi c permeability of their skin. “Amphibians generally have very
high rates of water turnover unless, like fossorial forms, they exploit environmental situations where water fl uxes across their highly permeable skins are low.
Many amphibians have remarkable tolerances to osmotic imbalances, and are able
to rectify these rapidly when water becomes available,” (Shoemaker and Nagy
1977 ; see also Neill 1958 ). Salinity potentially infl uences the abundance and
distribution of amphibians by imposing osmotic stress (Smith et al. 2007 ). The
issue of salinity effects on amphibian biology and ecology has recently drawn
more attention, for at least two reasons (see for review Wu and Kam 2009 ): fi rst,
several studies have revealed that amphibians breed in brackish water more
commonly than originally thought, and that they exhibit interesting physiological
and ecological adjustments to increased salinity stress; second, amphibians are
important indicator species for freshwater ecosystems that face increased
salinization due to natural causes, or to anthropogenic ones such as salt pollution
resulting from road de-icing salt runoff.
In contrast to amphibians, reptiles, due to their low skin permeability, uricotelism, and salt glands, are well adapted to remain in water. Amphibians adapted to
saline media store solutes and remain at least slightly hyperosmotic to their environment (see for review Schoemaker and Nagy 1977 ).
As discussed by Natchev and co-authors:
“Due to their highly vascularised and permeable skins, amphibians have a low
capacity to handle increased salinity in the waters they inhabit. Nevertheless, a
few species are able to live in brackish and even hypersaline waters. Reports on
adult amphibians, as well as their tadpoles, living under saline conditions are
numerous; but only a few amphibians can survive prolonged exposure to sea
water. Among anuran species, adaptations to elevated salinity differ considerably. One ranid species – the crab eating frog, Fejervarya cancrivora (Gravenhorst
1829) – is considered to possess the highest salinity tolerance among amphibians. In this species, 50 % of the larvae survived in up to 80 % sea water – equivalent to 0.5 %M Cl,” (Natchev et al. 2011 ; see also Beebee 1985 ; Dunson 1977 ;
Karraker 2007 ; Sillero and Ribeiro 2010 ; Spotila and Berman 1976 ; Wu and
Kam 2009 ).
14 Epilogue