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Chapter 5
Contribution of Forensic Analysis to Shark Profiling
Following Fatal Attacks on Humans
Eric Clua and Dennis Reid
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/intechopen.71043
Provisional chapter
Contribution of Forensic Analysis to Shark Profiling
Following Fatal Attacks on Humans
Eric Clua and Dennis Reid
Additional information is available at the end of the chapter
Abstract
Size assessment and species identification are paramount after a fatal attack for profiling
aproblem-animalthat could be specifically eliminated. In addition to ecological and
behavioural data about candidate species, forensic analysis can provide critical informa-
tion for achieving this goal. After providing basic information about fatal attacks and
the anatomical features of the three species (white shark, tiger shark and bull shark) that
are responsible for >80% of lethal interactions, this chapter presents the most used tools
for assessing the species and size of a potential attacker. The size assessment can be done
through measurements (on the body of the victim or from good-quality photographs) of
the bite width (BW) and bite circumference (BC); the size is then obtained from regres-
sions from the literature between BW/BC and total length. The average interdental
distance (IDD) is also used through a similar process. Finally, other details of the
wounds, such as the shape of the bite margin or of flesh flaps that directly depend on
the jaw characteristics, can also be used to contribute to the final assessment. Although
important, a forensic analysis should be complemented by data on shark ecology and
behaviour for a more reliable conclusion.
Keywords: agonistic behaviour, shark bites, wound analysis, species identification,
interdental distance, attacker total length, flesh flaps
1. Introduction: why profiling of sharks?
Although shark populations are facing declines worldwide, recorded instances of unprovoked
attacks by sharks on humans have been increasing in recent years, stirring public concern and
generating radical policies such as blind culling. The annual average number of fatal attacks
increased from 4.3 persons per year (20012010) up to an average of 8.0 persons per year
between 2011 and 2015 [1]. Such an unexpected trend can mainly be explained by a significant
increase of the number of sea users that increases the probability of encounter between these
© The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,
distribution, and eproduction in any medium, provided the original work is properly cited.
DOI: 10.5772/intechopen.71043
© 2018 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
marine predators and humans as shown in Australia [2]. In California, despite increasing
records of white shark (Carcharodon carcharias) attacks, the individual attack risk for ocean
users has decreased by >91% over a 63-year period (19502013) [3].
The triggers of shark attacks on humans are not well understood and still remain controversial.
Such an understanding of attack motivation is jeopardized by the low number of attacks
around the world, the scarcity of witnesses and the difficulty to observe an underwater event.
A better understanding of shark motivations and behaviour through forensic analysis should
at least partly help to avoid adverse outcomes in human encounters with these endangered
creatures [4, 5]. If there is a witness to an attack, comparison of display features between the
different species of potentially dangerous sharks can help in defining implications for shark-
human interactions and suggests responses which may decrease the likelihood of attack for
swimmers or divers faced with a postural display by a shark [6]. After the attack, the bite
structure of the wounds may reflect the motivation and behaviour of the shark [7]. It can also
allow the identification of the species involved in the attack and the accurate assessment of the
animal size. The profiling (and potential elimination) of problem individuals(see [8]) should
be preferred to implementing inefficient blind culling of sharks (see [9]), whatever their species
or size, as was recently the case in Western Australia and La Reunion island. In this French
island of the Western Indian ocean, the decision to launch a culling campaign was adopted
after five fatal attacks that occurred between 2011 and 2013; it not only removed tens of sharks
(mainly tiger Galeocerdo cuvier and bull Carcharhinus leucas sharks) but also a white shark that
was culled in October 2015, although this species is protected by international regulations.
However, innovative solutions (to be set up in the near future) for spotting and eliminating the
specific problem individualsrequire early and efficient shark profiling after an attack.
The purpose of this chapter is to provide marine biologists or medical practitioners potentially
involved in the postmortem analysis of a shark attack with the basic knowledge for assessing
the species and size of a shark, based on bite features and tooth imprint. Our focus will remain
on the data that should be collected and analysed from the wounds on a shark bite victim. This
chapter does not include the ecological aspects (including life traits and behaviour of the
sharks) which are a critical part of the holistic analysis of a shark attack in order to identify
the shark species potentially involved in a fatal interaction. Neither does it include the prob-
lems that may appear when cadavers remain in the water for a significant period, creating
several problems for diagnostics as shown by [10], nor forensic anthropology that examines
taphonomic evidence of marine deposition and shark-feeding activities on human remains (see
[11]). The focus remains on the postmortem analysis that can be conducted in the framework of
an autopsy done in few hours that follow a fatal attack or the analysis conducted on photo-
graphs of the body, once quality images and suitable metrics are available.
2. Shark jaws as potential lethal weapons
Most sharks are predators that feed on other animals they capture, facilitated by adapted jaws
holding several lines and rows of teeth. In contrast to mammalian teeth, shark teeth contain
fluorapatite, Ca
5
(PO
4
)F, which is harder than hydroxyapatite [12]. Teeth may have different
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis58
functions and thus different structures and hardness. For example, teeth of the mako shark
I. oxyrinchus are curved to the interior and are used to puncture flesh of the prey, while teeth of
tiger shark G. cuvier have serrated margins and are mainly used for cutting the prey in a
sawing motion (Figure 1). The serrations vary from one species to another in coarseness and
in distribution along tooth edges. Serrated teeth can make greater use of the available biting
forces, and they have a greater cutting effect than do smooth-edged teeth (i.e. mako shark
I. oxyrinchus). The latter depend upon friction which, because the coefficient friction is always
less than 1.0 (often very much less), can make use of only a fraction of the total bite force [13].
However, smooth tooth blades can pierce prey with less resistance and are less prone to
binding (becoming immobilized) in the prey tissue [12]. In carcharinids (including the bull
shark C. leucas), heterodonty is characterized by triangular and serrated teeth on the upper jaw
aiming at cutting, while teeth from the lower jaw are slender and smoother (see Section 3.4),
acting as puncturing/holding devices before the shark starts moving the head laterally for
cutting the tissues.
Figure 1. (A) Jaw of a tiger shark, Galeocerdo cuvier, showing the specific shape of the upper (A1) and lower (A2) teeth that
are similar, showing homodonty between both jaws. The tiger shark tooth displays a strong distal notch (X), as well as
fine serrations on mesial sides (Y) and coarse serration on the distal shoulder (Z). (B) Jaw of a mako shark, Isurus
oxyrinchus, showing curved and thin teeth, smooth-edged without serrations, with a slight heterodonty between both
jaws, teeth from the upper jaw (B1) being slightly thicker than those (B2) of the lower jaw (photos courtesy of Simon De
Marchi).
Figure 2. (A) Close-up of central lower jaw of a tiger shark, Galeocerdo cuvier, showing the specific shape and position of
teeth from the lower jaw. Each tooth is named based on its specific position as follows: First L stands for Lower, second L
for left and R for right. LL1, LL2, etc. constitute the first line on the left part of the lower jaw. Note behind LL1 and LR1, the
replacement teeth (second row) (LL1and LR1) that can be responsible for parallel teeth impressions. LL1, LL1, etc.
constitute the first row of the left part of the lower jaw. (B) Complete jaw of a tiger shark, Galeocerdo cuvier (photo courtesy
of Simon De Marchi), that can be characterized by the jaw width, also called bite width(BW), and the jaw circumference,
more often named bite circumference(BC). Both measurements can apply for upper and lower jaws, respectively (photos
courtesy of Thomas Vignaud, left, and Simon De Marchi, right, for strict scientific use).
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Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis60
white sharks do not have symphyseal teeth [24]. The first and second anterior teeth (UR1 and
UR2) of white sharks are erect and nearly symmetrical, while the lateral teeth (UR4 and UR5)
become progressively slanted towards the jaw corner [25]. As described by [20], the upper
dentition of white sharks features reversed intermediate teeth (UR3 and UL3) (see Figure 4).
The reversed intermediate teeth (UR3 or UL3) create a significantly larger interspace measure-
ment between it and the first lateral teeth (UR4 or UL4) than between any other two teeth of
the upper jaw (Figure 4). Generally the large gaps that exist between teeth frequently lead to
torn flaps of the skin and flesh between clear-cut punctures. These features should of course be
taken into consideration when analysing a bite potentially from a white shark (see Section 4.3).
3.3. The tiger shark (Galeocerdo cuvier)
Both jaws have large teeth with curved cusps and finely serrated edges. Each tooth has a deep
notch on the outer margin lined with numerous cusplets. Upper and lower teeth are similar in
shape and size and decrease in size as they move back towards the corners of the mouth. There
are 1824 teeth in each jaw, these teeth forming a single cutting edge (Figure 5). The teeth have
large cusps, forming a cockscomb shape, with prominent serrations [26]. The strong enamel
cusps and serrations help strengthen the tooth structure and dissipate the biting stresses [27].
This makes the tiger shark jaw an extremely efficient and unique cutting tool [28].
The tiger shark is also unique because it has highly kinetic jaws that are exceptionally broad-
based, heavily calcified and fused at the symphyses [29]. This allows for the single row of
cusped, serrated teeth to extend out from the skull, seize the prey and begin to saw into the
bone, performing the saw-bitingtechnique [30]. The broad, heavily calcified jaws, supported
Figure 3. (A) General features of the white shark dentition, showing (B) a sigmoid pattern along a vertical axis of the jaw;
anterior teeth are enlarged; anterior, intermediate and lateral teeth are compressed and form a continuous cutting edge;
intermediate teeth are enlarged and over two-thirds the height of adjacent anteriors, with reversed cusps that are directed
anteromedially. Jaws display a strong heterodonty with (B1) triangular upper teeth and (B2) slender lower teeth, as well as
(C) large interdental gaps between teeth from both jaws (here the lower jaw) (photos courtesy of Douglas Seifert and
Simon De Marchi for strict scientific use).
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Figure 4. White shark dentition and terminology: (A) jaw terminology, tooth identification and measurements, showing
location (indicated by chord a^b) of the intermediate bar between the intermediate (UR3 or UL3) and first lateral (UR4 or
UL4) teeth, and (B) dice diagram of interspace ratio between successive pairs of upper teeth, where vertical bar1 = range,
horizontal bar1 = mean, white box1 = standard deviation and hashed box1 = 95% confidence limits. In both (A) and (B),
the vertical dashed line indicates head axis through the jaw symphysis (adapted from Ref. [20]).
Figure 5. (A) General features of the tiger shark Galeocerdo cuvier dentition, showing (B) a sigmoid pattern along a
horizontal axis of the jaw; teeth of (B1) the lower jaw and (B2) upper jaw are of similar shape showing homodonty (photos
courtesy of Thomas Vignaud and Simon De Marchi for strict scientific use). (C and D) Right side of a typical tiger shark
Galeocerdo cuvier jaw illustrating the single cutting edge formed by a single row of functional teeth (adapted from Ref. [31]).
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis62
by the extra-strong symphyseal fusion, reinforce the entire jaw apparatus and enable the shark
to bite through very hard objects such as shells of chelonids [26].
3.4. The bull shark (Carcharhinus leucas)
Upper teeth of the bull shark are broad, triangular and strongly serrated, with erect or slightly
oblique cusps, and their bases overlap with each other (Figure 6); lower teeth have a broad
base and are narrow and slender with fine serrations, but no overlap with adjacent teeth bases.
Usually, there are 13/12 rows of anteroposterior teeth in each jaw half, but they vary from 12 to
14/12 to 13 [32] (Figure 6).
As for many carcharhinids, upper teeth are primarily used to cut and saw (sideways move-
ment along a surface when embedded in it, with ongoing perpendicular pressure); lower teeth
are primarily used to puncture and hold prey item in position, with limited capability of
cutting and sawing [7].
4. Post-mortem reconstruction of body length based on wound analysis
Along with the jaw and teeth features of the main candidate species, wound examinations
usually focus on the number of bites, margin structure, tooth imprints, wound depth and
tissue loss in order to assess the species identity [34, 35]. However, most of the time, these data
are insufficient for a reliable identification and must be considered with ecological data about
the presence and behaviour of the species (pelagic vs. coastal affinities, seasonality, etc.) and/or,
if available, data provided by potential witnesses of the attack.
Figure 6. (A) General features of bull shark dentition, showing (B) upper and lower jaws; upper teeth (B2) form a
continuous cutting edge with strong overlapping between teeth (C), while lower teeth (B1) are slender, displaying clear
heterodonty. (D) Teeth from the upper jaw are usually more numerous than those from the lower jaw (adapted from Ref.
[33]) (photos courtesy of Thomas Vignaud and Simon De Marchi for strict scientific use).
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Historically, the size of the animal was assessed by comparing the length of the individual
wound margins with jaws from known-sized animals [7]. Also, regressions that can provide
the size of an animal based on the bite width (BW) are available (see Table 2 for a review of
regressions available from the litterature for white and tiger sharks).
However, inspired by studies conducted on cetaceans [39] and based on anatomical differences
of jaws and teeth within shark species, Lowry et al. [40] proposed a forensic analysis method of
shark bite wound patterns. It is based on the determination of a standard relationship between
the measure of the average interdental distance (IDD) and the bite circumference (BC) of the
jaw with the individuals total length (TL). The IDD and BC are allometric with the global size
and are accurate predictors of the TL of a species-individual. Indeed, one of the numerous
elasmobranch characteristics is a continuous replacement of the teeth throughout life, allowing
the jaw growth. The number of teeth remains constant, but each new tooth is slightly larger
than the one it replaces [41].
Thus, nowadays, in order to estimate length of a shark from an autopsy or file pictures, it
might be rapid and reasonable to measure either interdental distances or bite radii from upper
or lower jaws, whatever measurements are available, and apply them to established loglog
regressions provided by [40] (see Table 3).
If the IDD and BC can provide critical information, they might be insufficient for a reliable
result. It is therefore necessary to include other measurements of the wounds. Hereafter, we
provide a series of case studies that indicate complementary tools that are available in regard
to the situation and the available data.
Species Great white shark Carcharodon carcharias Tiger shark Galeocerdo cuvier
Ref. [36] [37] [38] [39]
Regression TL = (BW + 2.4642)/0.0986 BW = 10.4% TL +/1.3 BW = 11,7% TL +/1.7 BW = 0.12 TL +/7.99
n 6 (from 163 to 510 cm TL) 14 M + 19 F (from 170 to
391 cm TL)
10 M + 20 F (from 104 to
410 cm TL)
93
Table 2. Estimated total length (TL) from bite width (BW) for the great white shark and the tiger shark using regressions
from the literature.
Type Jaw Regression r
2
p
IDD Upper Y = 1.005x2.111 0.98 <0.001
Lower Y = 0.925x1.808 0.97 <0.001
BC Upper Y = 1.007x0.800 0.98 <0.001
Lower Y = 0.966x0.743 0.99 <0.001
Average interdental distance and bite circumference represent the dependent variables, whereas total length is the
independent variable. r
2
= correlation coefficient; p= significance level.
Table 3. Loglog regression between average interdental distance (IDD) or bite circumference (BC) and total body length
of white sharks, Carcharodon carcharias, based on [40].
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis64
4.1. The use of the bite width (BW) and bite circumference (BC)
Case study A: description of the wound on a 23-year-old female fatally bitten in a shallow water lagoon
in New Caledonia. This case study was adapted from [4244] (same case).
A single large bite was made to the right thigh, from the hip to the knee, with a length of 38 cm
(Figure 7A). The thigh was cut deeply, with the femur bone broken at the level of the hip. The
muscular mass was sectioned but was still attached to the femur bone whose distal part was
still articulated to the knee. Despite the large bite, almost no tissue was removed as shown by
the repositioning of the scalloped muscular mass on the leg (Figure 7B); the inner and outer
margins on the wound on the inner part of the thigh fit together well although they are
somewhat swollen. The blood vessels were divided, and according to the medical certificate,
the victim died from exsanguination and hypovolemic shock. Apart from this large bite on the
right thigh, no other wounds were identified on the body.
Given the size of the BC, the hypothesis of the bull shark was rejected to favour either a large
white or tiger shark. Table 4 provides regressions for these two species between the total
length of the shark and the width of the mouth/jaw or that of the bite, from the literature.
Considering the size of the bite width of 38 cm [44], the total length of the shark would range
between 352 and 410 cm TL for a great white shark (for a similar bite width, a tiger shark would
be between 250 and 383 cm TL) (Table 4).
Using a BC of 596 mm [44] and based on the regressions provided by [40], the species involved
in this fatal attack seems to be a great white shark of about 3.5-m TL (Figure 8). However, these
regressions also show that given a BW of 38 cm, the BC should be much lower than 59.6 cm for
the attacker to be a tiger shark for which the TL would range from 250 to 383 cm TL (as shown
in Table 4). The formula by [40] shows that a tiger shark with a 38-cm BC would have a
TL >410 cm (Figure 8). This is due to the curvature of the BC which is different between the
two species. The hypothesis of the white shark should then prevail. Also, based on behavioural
features of the attack (provided by a witness), Clua and Séret [42, 43] concluded that the
candidate species for this 2007 attack in Lifou Island was a white shark and not a tiger shark
as supported by Tirard et al. [44]. This choice seems to be supported by the tools provided by
Lowry et al. [40].
4.2. The use of the interdental distance (IDD)
As demonstrated by [40], the teeth sizes of some shark species vary directly with the total
length (TL) of an individual, and a log-linear relationship exists between those two variables.
The measure of the IDD can therefore give a reliable estimate of the TL of an individual for
most species. The relationship between the BC and length gives a minimal estimate of a shark
TL. It is less informative than the IDD because the marks left on the organism or object can be
partials, as only a part of the jaw is often used during the bite.
The IDD is measured between adjacent teeth in the first six tooth files (a tooth in the functional
row and its replacing teeth are a tooth file) on each side of the symphysis. It is the measure
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Figure 7. (A) Shark bite on the right thigh of the victim. X shows the bite width (BW) and Y the bite circumference (BC)
that were accurately measured on the victim and used for the assessment of the shark size. The bite is not total; the thigh
was not removed but is still attached to the knee; the femur is broken at level of hip. (B) The repositioning of the thigh
scalloped by the bite shows that there was no significant loss of soft tissue (photos courtesy of Gendarmerie de Lifou for
strict scientific use).
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis66
between the tip of a functional tooth and the tip of the functional tooth of the adjacent file (see
the interspace between teeth ends from Figure 4). The symphyseal teeth are excluded if present;
they are often small, misshaped and randomly arranged. The IDD are measured on both sides of
each jaw which leads to a total of 20 measurements for each individual [40].
Case study B: description of the wound on a 19-year-old male surfer who was fatally bitten on the outer
slope of the barrier reef in New Caledonia (adapted from Ref. [45])
Based on the body examination and the witnessdeclaration, it was evident that the shark
attack was violent and sustained, with several strikes (> 3). Four main wounds could be
distinguished: the right thigh was fleshless from the hip to the knee (with exposed femur), the
right arm was missing, the right calf showed a large wound with no loss of tissue and a smaller
wound was located on the right ankle which displayed clear cuts on medial and lateral sides
that had dislocated the joint (Figure 9). The autopsy physician determined that death was
probably caused by a cardiopulmonary collapse due to the huge haemorrhage on the severing
of the axial and femoral blood vessels. To conduct the analysis of the wounds, we mainly used
the interdental distance(IDD) and the bite circumference(BC) for assessing the species and
size of the shark. Accurate calculation of IDD is actually easier with partial bites, and there was
only one photo that could be effectively used for this calculation, showing at the same time a
partial bite and a measuring scale (Figure 9C).
Species Great white shark Carcharodon carcharias Tiger shark Galeocerdo cuvier
Ref. [36] [37] [38] [39]
Formula TL = (BW + 2.4642)/0.0986 BW = 10.4% TL +/1.3 BW = 11.7% TL +/1.7 BW = 0.12 TL +/7.99
n 6 (from 163 to 510 cm TL) 14 M + 19 F (from 170 to
391 cm TL)
10 M + 20 F (from 104
to 410 cm TL)
93
BW (cm) Calculated TL (cm) Calculated TL (cm) Calculated TL (cm) Calculated TL (cm)
38 410.4 352.9377.9 310.3339.3 250.1383.3
Table 4. Estimated total length (TL) from bite width (BW) for the great white shark and the tiger shark using regressions
from literature.
Figure 8. Screen copies of the results obtained through the excel table from Ref. [40]. In addition to the scientific paper,
[40] provide as a supplementary material an excel table that directly uses the loglog regressions. You must enter either
the average IDD or (in this case A) the BC for obtaining the potential species and shark size involved in the bite. NB: the
comment exceeds TL range regression is based ondoes not mean that the species cannot be responsible for the bite, but
that the size is larger than the size interval of the sampled animals, indicating potential unreliability of the assessment.
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The average IDD calculated on the partial bite of the right calf inflicted by teeth of the upper
jaw of the shark (see Figure 9B) was 21.75 mm. Based on [40], only two shark species have
upper jaw features fitting with such an IDD: a 2.65-total length (TL) white shark, C. carcharias,
or a 2.25-TL longfin mako, Isurus paucus. The occurrence of a longfin mako off the reef barrier
on the west coast of New Caledonia has an extremely low probability, as the species has a
pelagic distribution. Furthermore, the features of the teeth marks on the body do not fit with
elongated, thin and smooth-edged teeth (cf. Isurus sp.) but rather with large and serrated teeth
with broadly triangular cusps, such as those of a white shark (Carcharodon sp.). We therefore
Figure 9. (A) The body of the 19-year-old victim showing the main two wounds in the right arm has been clearly
severed 10 cm below the joint of the shoulder (top of the photo); all flesh and muscles have been removed from the
right thigh, from the hip down to just above the knee (central and lower part of the photo). (B) Arcs B1 and B2 show
the two main bites to the right calf, with tooth impression of the top jaw. For the left-hand arc (B1), it appears that
the shark held the leg for a very short time, with a shallow holding bite, and then eased off before biting down and
ripping with full force, just below the labelled marks (B2). On B2, we could define the first isolated tooth mark (top
left) as the first upper left tooth (UL1), followed then on the right by the upper right teeth (UR1 to UR5). (C) The
glove box (24 cm wide) gave us a scale allowing us to calculate bite width as approx. 17 cm, distances between UR1
and UR2 (D1) to be approx. 2.0 cm and UR2UR3 as (D2) approx. 1.5 cm, UR3UR4 (D3) approx. 2.4 cm and UR4
UR5 (D4) approx. 2.8 cm. The average IDD for the left bite arc is approximately 3 cm. The bite width probably
represents the jaw width at the fifth tooth from the symphysis (photos courtesy of Gendarmerie de Bourail for strict
scientific use).
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis68
concluded that a juvenile white shark of approximately 2.7-m TL was responsible for this fatal
attack.
4.3. The use of other details
Besides the use of IDD and BC for assessing the species and size of the shark, the analysis of
the pattern of the teeth marks, directly linked to the species-specific teeth characteristics of the
shark, can also be compared with dental impressions of the three main candidate species.
Rapid-curing vinyl polysiloxane impression material putty can be used to make these impres-
sions using dried jaws from sharks of accurately measured total length (Figure 10). Such a
process can help through the identification of specific marks and positioning of the teeth on the
wounds, including the shape of tissue and flesh flaps that depend on the teeth position (see
Case studies C and D).
Case study C: description of the wounds on a 15-year-old male kite surfer who was fatally bitten in a reef
passage of the barrier reef of New Caledonia (adapted from Ref. [47])
On the basis of the body examination and the witnessesstatements, it was evident that
the shark approached the victim from below. A major wound (W1, 38 cm in length) with a
significant loss of tissue was centred on both sides of the knee in the front and internal sides of
the leg. Two other smaller wounds, with almost no loss of tissue, were inflicted on the back of
the leg: one at the level of the thigh (W2, 18 cm in length and 10 cm in width) and another
behind the knee and the top of the calf (W3, 30 cm in length and 7 cm in width) (Figure 11). As
mentioned in the autopsy report, the death was undoubtedly caused by a cardiopulmonary
collapse due to the huge haemorrhage following the severing of the left femoral blood vessel
through the first wound.
Figure 10. Teeth impressions from the lower jaw of the three main candidate species of shark, potentially involved in a
fatal attack (from left to right): (A) white shark, Carcharodon carcharias; (B) tiger shark, Galeocerdo cuvier; and (C) bull shark,
Carcharhinus leucas. The teeth impressions of tiger shark are long and thin, very close to each other, sometimes almost
overlapping. Teeth impressions of bull shark and white shark are more needle-likeand separated, leading to much
higher interdental distances (IDD) for a given size of shark. These jaws were collected from the NSW Shark Meshing
Program [46] (photos courtesy of Simon De Marchi for strict scientific use).
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The analysis of the first wound (W1) revealed that it was probably the result of two
different adjacent and overlapping bites or one single bite inflicted as the leg was bending
(see [47] for details). Analysis of the lower bite showed that the orientation of the tooth
impressions and their shape, together with the small, smoothly sliced flaps, and the very
smooth arc of the upper jaw bite, indicate a tiger shark as probably responsible for this
attack. This hypothesis was confirmed by the observation of the three teeth impressions
from the bottom left of the bite corresponding to this wound. These impressions are more
or less parallel and have sharp cut corners, which is consistent with a tiger shark
(Figure 11A). Also, the shape of the tooth impressions shows no clear morphological
differences between those from the upper and lower jaws, indicating dignathic homodont
jaws [47], characteristic of the tiger shark, compared to the white shark and bull shark
which have dignathic heterodont jaws. In addition to these elements, the shape of some
flesh flaps showed that there was an almost overlapping between the teeth (Figure 11A
and B). This detail eliminates the white shark, and regarding the bull shark hypothesis,
Figure 11. (A) Lateral view of the lower part of the first wound (W1). Arrow 1 shows the specific parts of the wound with
sharp and square corners, quasi-parallel cuts, that are characteristic of a tiger shark teeth impression. (a) Close-up view
on (a): showing a skin flap which results from two overlapping teeth (T and T + 1). (B) The third wound (W3) has an
elongated frame with length 30 cm width 7 cm. (b) Close-up view on (b): showing a skin flap which also results from two
overlapping teeth. Arrows 2 and 3 indicate two superficial scratches inflicted by two symphyseal teeth (at the junction of
the two jaw segments) (photos courtesy of Gendarmerie de Koumac for strict scientific use).
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis70
the overlapping in teeth of the upper jaw is so efficient (see Figure 6) that the presence of
flesh flaps is unlikely.
Case study D: complementary wounds evidence for shark ID from [42,45]
Case studies A and B also provide examples of evidence that support the identification of the
attacking species. Actually, in both cases, the wounds presented large flesh flaps that are
specific to the white shark, given the specific position of its teeth and the large interdental
spaces (see Figures 3 and 4). In both case studies, it is possible to identify at least a large flesh
flap that results from the space between the two first teeth of the upper jaw (UR1 and UL1),
combined with the absence of symphyseal teeth (see Figure 12).
5. Conclusion
The present research aims at introducing marine biologists and medical practitioners to the
basic knowledge necessary for analysing the wounds left by a shark bite. The implementation
of these techniques is dependent on directly observing the victim or of the availability of
quality photographs. Unfortunately photographic images often do not include any scale mea-
sure which significantly lowers the probability of an accurate conclusion.
In practice, these techniques can help but are often insufficient for species identification. It is
then necessary to stress the benefit and utility of taking an interdisciplinary approach to
forensic anthropological casework, specifically collaborating with a scientist with expertise in
shark biology in cases of suspected shark attack. This type of integrated approach is common
in taphonomic analyses and should be considered best practice [11].
Figure 12. (A) Close-up of the wounds from case A that shows (X) a large flesh flap that seems to correspond to the
symphyseal space of a white shark jaw, as well as (Y) and (Y0) flesh flaps that correspond to the large space that exist
between UR3/UL3 and UR4/UL4 (see Figure 4). The dashed lines indicate the probable biting axis that can explain why
both flesh flaps are not exactly opposite each other. (B) Close-up of a partial bite from case B, arrows show a large flesh
flap that corresponds to the symphyseal space of a white shark jaw (photos courtesy of Gendarmeries de Lifou and
Bourail for strict scientific use).
Contribution of Forensic Analysis to Shark Profiling Following Fatal Attacks on Humans
http://dx.doi.org/10.5772/intechopen.71043
71
Acknowledgements
In the context of case studies A and D, we wish to thank M. Neko Hnepeune, Mayor of Lifou
Island; M. Dominique Mole, General Secretary of Lifou Island; M. Afif Lazrak, General Secretary
of the administrative subdivision of the Loyalties Islands; and M. H. Ansquer, the vice-coroner
of the French Republic in Noumea for trusting us in investigating the case. We also thank the
parents of the victim for their understanding and her friend (L.L.) for her collaboration. In the
context of case study B, we wish to thank the victims mother, Rose-Marie Hannecart, for
allowing us to conduct and publish this analysis. The file that allowed this analysis was kindly
provided by the Procureur de la République, Tribunal de Noumea, Nouvelle-Calédonie, under
the file reference Parquet/A0904702; additional high-resolution images were provided by the
Brigade de gendarmeriede Bourail. In the context of case study C, we wish to mention that the
file that allowed this analysis was kindly provided by the Procureur de la République, Tribunal
de Noumea, Nouvelle-Calédonie. We also specifically thank Thomas Vignaud, Douglas Seifert
and Simon De Marchi for the use of their outstanding photographs.
Author details
Eric Clua
1
* and Dennis Reid
2
*Address all correspondence to: eric.clua@univ-perp.fr
1 PSL, Labex CORAIL, CRIOBE USR3278 EPHE-CNRS-UPVD, University of Perpignan,
Perpignan, France
2 New South Wales Department of Primary Industries, Sydney Institute of Marine Science,
Mosman, Australia
References
[1] ISAF. International Shark Attack Files. Website of Florida Museaum of Natural History.
Available from: https://www.floridamuseum.ufl.edu/fish/isaf/home/ [Accessed 15-08-2017]
[2] West JG. Changing patterns of shark attacks in Australian Waters. Marine and Freshwater
Research. 2011;62(6):744-754
[3] Ferretti F, Jorgensen S, Chapple TK, De Leo G, Micheli F. Reconciling predator conserva-
tion with public safety. Frontiers in Ecology and the Environment. 2015;13(8):412-417
[4] Caldicott DG, Mahajani R, Kuhn M. The anatomy of a shark attack: A case report and
review of the literature. Injury. 2001;32(6):445-453
[5] Ritter E, Levine M. Use of forensic analysis to better understand shark attack behaviour.
The Journal of Forensic Odonto-Stomatology. 2004;22(2):40-47
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis72
[6] Martin RA. A review of shark agonistic displays: Comparison of display features and
implications for sharkhuman interactions. Marine and Freshwater Behaviour and Phys-
iology. 2007;40(1):3-34
[7] Ritter EK, Levine M. Bite motivation of sharks reflected by the wound structure on
humans. American Journal of Forensic Medicine and Pathology. 2005;26:136-140
[8] Linnell JD, Odden J, Smith ME, Aanes R, Swenson JE. Large carnivores that kill livestock:
do problem individualsreally exist? Wildlife Society Bulletin. 1999:698-670
[9] Wetherbee BM, Crow GL, Lowe CG. Distribution, reproduction and diet of the gray reef
shark Carcharhinus amblyrhynchos in Hawaii. Marine Ecology Progress Series. 1997;151:
181-189
[10] Byard RW, James RA, Gilbert JD. Diagnostic problems associated with cadaveric trauma
from animal activity. The American Journal of Forensic Medicine and Pathology. 2002;23(3):
238-244
[11] Stock MK, Winburn A,Burgess GH. Skeletal indicators of shark feeding on human remains:
Evidence from Florida forensic anthropology cases. Journal of Forensic Sciences. 2017; DOI:
10.1111/1556-4029.13470
[12] Frazzetta TH. The mechanics of cutting and the form of shark teeth (Chondrichthyes,
Elasmobranchii). Zoomorphology. 1988;108(2):93-107
[13] Enax J, Prymak O, Raabe D, Epple M. Structure, composition, and mechanical properties
of shark teeth. Journal of Structural Biology. 2012;178(3):290-299
[14] Byard RW, Wick R, Simpson E, Gilbert JD. The pathological features and circumstances of
death of lethal crush/traumatic asphyxia in adultsA 25-year study. Forensic Science
International. 2006;159(2):200-205
[15] Whitenack LB, Motta PJ. Performance of shark teeth during puncture and draw: Implica-
tions for the mechanics of cutting. Biological Journal of the Linnean Society. 2010;100(2):
271-286
[16] Wroe S, Huber DR, Lowry M, McHenry C, Moreno K, Clausen P, Summers AP. Three-
dimensional computer analysis of white shark jaw mechanics: How hard can a great white
bite? Journal of Zoology. 2008;276(4):336-342. DOI: 10.1111/j.1469-7998.2008.00494.x
[17] Rasch LJ, Martin KJ, Cooper RL, Metscher BD, Underwood CJ, Fraser GJ. An ancient
dental gene set governs development and continuous regeneration of teeth in sharks.
Developmental Biology. 2016;415(2):347-370
[18] Nambiar P, Brown KA, Bridges TE. Forensic implications of the variation in morphology
of marginal serrations on the teeth of the great white shark. The Journal of Forensic
Odonto-Stomatology. 1996;14(1):2-8
[19] Hazin FH, Burgess GH, Carvalho FC. A shark attack outbreak off Recife, Pernambuco,
Brazil: 19922006. Bulletin of Marine Science. 2008;82(2):199-212
Contribution of Forensic Analysis to Shark Profiling Following Fatal Attacks on Humans
http://dx.doi.org/10.5772/intechopen.71043
73
[20] Martin RA, Hammerschlag N, Collier RS, Fallows C. Predatory behaviour of white sharks
(Carcharodon carcharias) at Seal Island, South Africa. Journal of the Marine Biological
Association of the United Kingdom. 2005;85(5):1121-1136
[21] Estrada JA, Rice AN, Natanson LJ, Skomal GB. Use of isotopic analysis of vertebrae in
reconstructing ontogenetic feeding ecology in white sharks. Ecology. 2006;87(4):829-834
[22] Clua E, Guiart J. Sharks of Oceania: Ethno-ecology of a Marine Predator. 2nd ed. Papeete:
Te Pito o te Fenua. 198 p; 978-2-9539509-8-4
[23] Shimada K. The relationship between tooth size and total body length in the white shark,
Carcharodon carcharias (Lamniformes: Lamnidae). Journal of Fossil Research. 2002;35:28-33
[24] Hubbell G. Using tooth structure to determine the evolutionary history of the white shark.
In: Klimley AP, Ainley DG, Editors. Great White Sharks: The Biology of Carcharodon
carcharias. San Diego: Academic Press; 1996. p. 9-18
[25] Bass AJ, DAubrey JD, Kistnasamy N. Sharks of the east coast of southern Africa. 4.
The families Odontaspididae, Isuridae, Cetorhinidae, Alopiidae, Orectolobidae and
Rhiniodontodae. In: Investigational Report No. 39. Durban: Oceanographic Research
Institute; 1975. p. 1-102
[26] Witzell WN. Selective predation on large cheloniid sea turtles by tiger sharks (Galeocerdo
cuvier). Japanese Journal of Herpetology. 1987;12(1):22-29
[27] Preuschoft H, Reif WE, Muller WH. Funktionsanpassungen in Form and Struktur an
Haifischzahnen. Zeitschrift fur Anatomie und Entwicklungs Geschichte. 1974;143:315-
344
[28] Corn KA, Farina SC, Brash J, Summers AP. Modelling toothprey interactions in sharks:
The importance of dynamic testing. Royal Society Open Science. 2016;3(8):160141
[29] Moss SA. The feeding mechanism of sharks of the family Carcharhinidae. Journal of
Zoology. 1972;167(4):423-436
[30] Clua E, Read T, Chauvet C, Werry J, Lee SY. Behavioural patterns of a Tiger Shark
(Galeocerdo cuvier) feeding aggregation on a whale carcass in Prony bay, New Caledonia.
Marine and Freshwater Physiology and Behaviour. 2013;46(1):1-20. DOI: 10.1080/
10236244.2013.773127
[31] Bigelow HB, Schroeder WC. Fishes of the western north Atlantic sharks. Memoirs, Sears
Foundation for Marine Research. 1948;1:53-567
[32] Compagno LJ. FAO species catalogue. Vol. 4. Sharks Of The World. An annotated and
illustrated catalogue of the shark species known to date. Part. 2: Carcharhiniformes. FAO
Fish synop. 125:250-655.
[33] Garrick JAF. Sharks of the genus Carcharhinus. NOAA Tech. Rep. NMFS Circ. 1982;
445:194
[34] Davies DH, Campbell GD. The aetiology, clinical pathology and treatment of shark
attack. Journal of the Royal Naval Medical Service. 1961;48:110-136
Post Mortem Examination and Autopsy - Current Issues From Death to Laboratory Analysis74
[35] Byard RW, Gilbert JD, Brown K. Pathologic features of fatal shark attacks. The American
Journal of Forensic Medicine and Pathology. 2000;21(3):225-229
[36] Long DJ, Jones RE. White shark predation and scavenging on cetaceans in the eastern
North Pacific Ocean. In: Klimley AP, Ainley DG, editors. Great White Sharks. The Biol-
ogy of Carcharodon carcharias. Academic Press: San Diego. 1996. p. 293-307
[37] Bass AJ, DAubrey JD, Kistnasamy N. Sharks of the east coast of southern Africa. 3. The
families Carcharhinidae and Sphyrnidae. Investigational Report No. 38. Durban: Ocean-
ographic Research Institute; 1975. p. 1-100
[38] Heithaus M. Shark attacks on bottlenose dolphins (Tursiop aduncus) in Shark Bay, Western
Australia: Attack rate, bite scar frequencies, and attack seasonality. Marine Mammal
Science. 2001;17(3):526-539
[39] George JC, Philo LM, Hazard K, Withrow D, Carroll GM, Suydam R. Frequency of killer
whale (Orcinus orca) attacks and ship collisions based on scarring on bowhead whales
(Balaena mysticetus) of the Bering-Chukchi-Beaufort Seas stock. Arctic. 1994;47:247-255
[40] Lowry D, de Castro ALF, Mara K, Whitenack LB, Delius B, Burgess GH, Motta P.
Determining shark size from forensic analysis of bite damage. Marine Biology 2009;156(12):
2483
[41] Moss SA. Shark feeding mechanisms. Oceanus. 1981/1982;24:23-29
[42] Clua E, Séret B. Unprovoked fatal shark attack in Lifou island (Loyalty Islands, New
Caledonia, South Pacific) by a Great White Shark, Carcharodon carcharias. The American
Journal of Forensic Medicine and Pathology. 2010;31(3):281-286
[43] Clua E, Séret B. Species identification of the shark involved in the 2007 Lifou fatal attack
on a swimmer: A reply to Tirard et al. (2015). Journal of Forensic and Legal Medicine.
2016;40:58-60
[44] Tirard P, Maillaud C, Borsa P. Fatal tiger shark, Galeocerdo cuvier attack in New Caledonia
erroneously ascribed to great white shark, Carcharodon carcharias. Journal of Forensic and
Legal Medicine. 2015;33:68-70
[45] Clua E, Reid D. Features and motivation of a fatal attack by a juvenile white shark,
Carcharodon carcharias, on a young male surfer in New Caledonia (South Pacific). Journal
of Forensic and Legal Medecine. 2013;20(5):551-554. DOI: 10.1016/j.jflm.2013.03.009
[46] Reid D, Robbins R, Peddemors V. Decadal trends in shark catches and effort from the
New South Wales, Australia, Shark Meshing Program 1950-2010. Marine and Freshwater
Research. 2011;62:676-693
[47] Clua E, Bescond PM, Reid D. Fatal attack by a juvenile tiger shark, Galeocerdo cuvier,ona
young male kitesurfer in a reef passage of New Caledonia (South Pacific). Journal of
Forensic and Legal Medicine. 2014;25:67-70
Contribution of Forensic Analysis to Shark Profiling Following Fatal Attacks on Humans
http://dx.doi.org/10.5772/intechopen.71043
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