98
– in the rostrum, these rods appear to be quite closely packed within a relatively
sparse framework of thin collagen fi brils;
– the low collagen content results in a low elastic component in the rostral bone,
which would account for its great stiffness and hardness, and its low bending
strength,” (Zylberberg et al. 1998 ).
For bone crack propagation in another marine mammals (e.g. in manatees,
which have all cortical bone, no trabecular and no marrow cavities) see Clifton
et al. ( 2008 ).
In contrast to turkey leg tendon, where calcium phosphate crystal growth
occurring along, but not inside, the fi brils (Traub et al. 1992 ), in the rostrum of
ziphiids, crystal nucleation may occur near the surface of collagen fi brils. Zylberberg
et al. ( 1998 ) proposed alternative hypothesis where “the rostrum mineral nucleation
and growth may have occurred in heavily mineralized fi brils, as in other bones, but
with most of the collagen being later removed from the mature mineralized fi brils.
This leaves only a loose framework of thin collagen around dense mineral rods,”
(Zylberberg et al. 1998 ) (Fig. 3.1 ).
However, what is the functional importance of this specialized compact rostrum
of extant and extinct ziphiids? As proposed by Lambert et al. ( 2011 ), “the most
convincing hypotheses can be classifi ed into three categories, related to three main
functional and ecological features:
– acoustics,
– deep diving,
– and intraspecifi c fi ghts between males,” (Lambert et al. 2011 ).
In odontocetes, the sound-producing organs in the forehead include air sacs
surrounding the phonic lips. These formations may act as acoustic mirrors for
echolocation and communication sounds. It is suggested that the production of
echolocation sounds occurs in the forehead, however, the transmission is made
through the fatty lump of tissue termed as melon . There are no doubts that in deep
divers like M. densirostris and Ziphius cavirostris which “have been recorded at depths
up to 1,251 and 1,888 m, with dive durations reaching 57 and 85 min, respectively,”
(Lambert et al. 2011 ), especially role will play the hydrostatic pressure. Defi nitively,
it strongly reduces the volume of air spaces within animal. It was suggested that
“density disparity between forehead tissues and highly compact bone could therefore
constitute an alternative acoustic refl ector,” (Lambert et al. 2011 ).
In her doctoral thesis (Campbell-Malone 2007 ) and subsequent collaborative
work, Campbell-Malone determined the physical and material properties of the
right whale jawbone and used those as the foundation of the fi rst biomechanical
models of vessel-whale collisions (Tsukrov et al. 2009 ) (Fig. 3.2 ). Unfortunately, one
of the most critically endangered whales in the world is the Eubalaena glacialis ,
also known as North Atlantic right whale (Right Whale Consortium 2005 ; see also
Kraus and Rolland ( 2007 )). The deaths statistics resulting from entanglement in
fi shing gear and vessel-whale collisions, accounted for 27 (67.5 %) of the 40 right
whales examined postmortem between 1970 and December 2006. Of those deaths,
21 (52.5 %) were attributed to vessel-whale collisions and at least 9 (22.5 %) of
those resulted from blunt contact with the hull of a vessel.
3 Biocomposites and Mineralized Tissues
– in the rostrum, these rods appear to be quite closely packed within a relatively
sparse framework of thin collagen fi brils;
– the low collagen content results in a low elastic component in the rostral bone,
which would account for its great stiffness and hardness, and its low bending
strength,” (Zylberberg et al. 1998 ).
For bone crack propagation in another marine mammals (e.g. in manatees,
which have all cortical bone, no trabecular and no marrow cavities) see Clifton
et al. ( 2008 ).
In contrast to turkey leg tendon, where calcium phosphate crystal growth
occurring along, but not inside, the fi brils (Traub et al. 1992 ), in the rostrum of
ziphiids, crystal nucleation may occur near the surface of collagen fi brils. Zylberberg
et al. ( 1998 ) proposed alternative hypothesis where “the rostrum mineral nucleation
and growth may have occurred in heavily mineralized fi brils, as in other bones, but
with most of the collagen being later removed from the mature mineralized fi brils.
This leaves only a loose framework of thin collagen around dense mineral rods,”
(Zylberberg et al. 1998 ) (Fig. 3.1 ).
However, what is the functional importance of this specialized compact rostrum
of extant and extinct ziphiids? As proposed by Lambert et al. ( 2011 ), “the most
convincing hypotheses can be classifi ed into three categories, related to three main
functional and ecological features:
– acoustics,
– deep diving,
– and intraspecifi c fi ghts between males,” (Lambert et al. 2011 ).
In odontocetes, the sound-producing organs in the forehead include air sacs
surrounding the phonic lips. These formations may act as acoustic mirrors for
echolocation and communication sounds. It is suggested that the production of
echolocation sounds occurs in the forehead, however, the transmission is made
through the fatty lump of tissue termed as melon . There are no doubts that in deep
divers like M. densirostris and Ziphius cavirostris which “have been recorded at depths
up to 1,251 and 1,888 m, with dive durations reaching 57 and 85 min, respectively,”
(Lambert et al. 2011 ), especially role will play the hydrostatic pressure. Defi nitively,
it strongly reduces the volume of air spaces within animal. It was suggested that
“density disparity between forehead tissues and highly compact bone could therefore
constitute an alternative acoustic refl ector,” (Lambert et al. 2011 ).
In her doctoral thesis (Campbell-Malone 2007 ) and subsequent collaborative
work, Campbell-Malone determined the physical and material properties of the
right whale jawbone and used those as the foundation of the fi rst biomechanical
models of vessel-whale collisions (Tsukrov et al. 2009 ) (Fig. 3.2 ). Unfortunately, one
of the most critically endangered whales in the world is the Eubalaena glacialis ,
also known as North Atlantic right whale (Right Whale Consortium 2005 ; see also
Kraus and Rolland ( 2007 )). The deaths statistics resulting from entanglement in
fi shing gear and vessel-whale collisions, accounted for 27 (67.5 %) of the 40 right
whales examined postmortem between 1970 and December 2006. Of those deaths,
21 (52.5 %) were attributed to vessel-whale collisions and at least 9 (22.5 %) of
those resulted from blunt contact with the hull of a vessel.
3 Biocomposites and Mineralized Tissues