118
3.2.6.3 Shark Teeth
Studying the functional morphology, structure, chemistry and materials properties
of unique and diverse shark teeth not only helps to understand the biological role
that teeth play in feeding of extinct, extant and living species, but also stimulate
progress in biological materials science, biomimetics and development of fi sh
inspired robotics.
In most fi sh, the teeth are homodont: all the teeth are roughly of similar sizes and
shapes. So called “dental lamina” is a structure producing teeth throughout the life
of the Chondrichthyans and represent an example of one of the earliest innovations
in sharks evolution. Tooth form is highly variable both within and between individuals
of sharks. Wide variety of shapes of the extant shark teeth can be represented
by teeth “ with triangular serrated cusps, oblique serrated and non-serrated cusps,
notched serrated cusps, non-serrated recurved cusps, multicusped teeth, and fl attened
tooth pavements, ” (Whitenack 2008 ). For example, the holocephalans and bradyodont (cochliodont) sharks, which feed by crushing hard-shelled molluscs and
crustaceans, possess fl at and pavement-like teeth, reinforced by tubes of pleuromic
dentine. There are numerous papers on tooth terminology and variation in sharks
with regard to tooth location and design (see for review Gudger 1937 ; Applegate
1965 ; Zangerl 1981 ; Compagno 1984a , b , 1988 ; Cappetta 1986 ; Powlik 1995 ;
Hubbell 1996 ; Ramsay and Wilga 2007 ). Thus, to briefl y summarize Whitenack and
Motta ( 2010 ), following types of teeth in sharks:
– “ clutching-type, small teeth, often with lateral cusplets;
– tearing-type teeth, which are considered to function best in puncture, have
narrow, tall cusps and are usually not serrated.
– cutting-type, teeth whose crowns are lingo-labially fl attened and widen towards
the base;
– Molariform teeth, such as those found in the heterodontids and many batoids,
fall into ‘crushing-type’ or ‘grinding-type’ ,” (Whitenack and Motta 2010 ) .
Shark tooth morphology determines their biological role (Whitenack and Motta
2010 ). It is established that “ teeth with different shape and/or size play different
roles during prey catching and handling in elasmobranchs, ” (Lucifora et al.
2001 ; see also Applegate 1965 ). Here, some examples. The bonnethead shark
Sphyrna tiburo (Carcharhiniformes) and the horn sharks Heterodontus spp.
(Heterodontiformes) are species with heterodonty. Both species possess posterior
teeth which are molariform and crush the hard food, however anterior teeth are
sharp and effi cient in grasping food (Tricas et al. 1997 ). The term Dental Insertion
Angles (DIA), is widely used in elasmobranchs studies and represents an angle
between the long axis of a jaw and the axis of a tooth. For example, a relationship
between the DIA and the cutting capability of teeth has been reported by Frazzetta
( 1988 ) during biomechanical investigations of serrated and smooth-edged shark
teeth. As summarized by Whitenack and Motta ( 2010 ):
“ Applying artifi cial blades and teeth from various shark species to compliant
materials, the author observed that smooth, slender teeth, such as those of the mako
3 Biocomposites and Mineralized Tissues
3.2.6.3 Shark Teeth
Studying the functional morphology, structure, chemistry and materials properties
of unique and diverse shark teeth not only helps to understand the biological role
that teeth play in feeding of extinct, extant and living species, but also stimulate
progress in biological materials science, biomimetics and development of fi sh
inspired robotics.
In most fi sh, the teeth are homodont: all the teeth are roughly of similar sizes and
shapes. So called “dental lamina” is a structure producing teeth throughout the life
of the Chondrichthyans and represent an example of one of the earliest innovations
in sharks evolution. Tooth form is highly variable both within and between individuals
of sharks. Wide variety of shapes of the extant shark teeth can be represented
by teeth “ with triangular serrated cusps, oblique serrated and non-serrated cusps,
notched serrated cusps, non-serrated recurved cusps, multicusped teeth, and fl attened
tooth pavements, ” (Whitenack 2008 ). For example, the holocephalans and bradyodont (cochliodont) sharks, which feed by crushing hard-shelled molluscs and
crustaceans, possess fl at and pavement-like teeth, reinforced by tubes of pleuromic
dentine. There are numerous papers on tooth terminology and variation in sharks
with regard to tooth location and design (see for review Gudger 1937 ; Applegate
1965 ; Zangerl 1981 ; Compagno 1984a , b , 1988 ; Cappetta 1986 ; Powlik 1995 ;
Hubbell 1996 ; Ramsay and Wilga 2007 ). Thus, to briefl y summarize Whitenack and
Motta ( 2010 ), following types of teeth in sharks:
– “ clutching-type, small teeth, often with lateral cusplets;
– tearing-type teeth, which are considered to function best in puncture, have
narrow, tall cusps and are usually not serrated.
– cutting-type, teeth whose crowns are lingo-labially fl attened and widen towards
the base;
– Molariform teeth, such as those found in the heterodontids and many batoids,
fall into ‘crushing-type’ or ‘grinding-type’ ,” (Whitenack and Motta 2010 ) .
Shark tooth morphology determines their biological role (Whitenack and Motta
2010 ). It is established that “ teeth with different shape and/or size play different
roles during prey catching and handling in elasmobranchs, ” (Lucifora et al.
2001 ; see also Applegate 1965 ). Here, some examples. The bonnethead shark
Sphyrna tiburo (Carcharhiniformes) and the horn sharks Heterodontus spp.
(Heterodontiformes) are species with heterodonty. Both species possess posterior
teeth which are molariform and crush the hard food, however anterior teeth are
sharp and effi cient in grasping food (Tricas et al. 1997 ). The term Dental Insertion
Angles (DIA), is widely used in elasmobranchs studies and represents an angle
between the long axis of a jaw and the axis of a tooth. For example, a relationship
between the DIA and the cutting capability of teeth has been reported by Frazzetta
( 1988 ) during biomechanical investigations of serrated and smooth-edged shark
teeth. As summarized by Whitenack and Motta ( 2010 ):
“ Applying artifi cial blades and teeth from various shark species to compliant
materials, the author observed that smooth, slender teeth, such as those of the mako
3 Biocomposites and Mineralized Tissues