Veterinary Research Communications, 14 (1990) 5-17
Copyright (C) Kluwer Academic Publishers

ESTIMATION OF THE TOTAL SURFACE AREA IN INDIAN
ELEPHANTS (ELEPHAS MAXIMUS INDICUS)
K.P. Sreekumar and G. NirmalanCollege of Veterinary and animal Sciences,
Kerala Agricultural University, Mannuthy, Trichur, Kerala, India 680651
ABSTRACT
Sreekumar K.P. and Nirmalan G., 1990. Estimation of the total surface are in Indian elephants (Elephas maximus indicus) Veterinary ResearchCommunications, 14(1), -17
Twenty-four adult Indian elephants (Elephas maximus indicus) of both sexes and different ages and weights, belonging to the Temple Devaswome,
the Forest Department of the Government of Kerala and Gemini Circus formed the experimental subjects from which formulae were derived to predict the
total surface area from either body measurements or areas of individual regions. Several models, using the parameters studied either singly or in combination, were tried independently for males and females and also for adults irrespective of sex. The best prediction of total surface area (s) in m2 was
obtained for adults irrespective of sex by using the two parameters, the height at the shoulders (H) in m and forefoot pad circumference (FFC) in m in theformula S=-8.245 + 6.807H +7.073FFC. No Significant imporvement in the accuracy of prediction resulted from the use of the independent best fit
formulae for males and females. The conventional method of using the exponential of body weight (kg) for predicting suface area was not found to yieldand equivalent accuracy in these animals.
Keywords: biometry, elephant, surface area

INTRODUCTION
Metabolic rate can be expressed as a function of the total
surface area during life. Even though expression in terms ofbody weight is preferred, the customary practice of expressing heat production in relation to surface area (Dale, 1984)
is still widely prevalent.
The surface area can be measured directly or it can be
estimated by conventional formulae. An attempt was madein the present work to estimate the total surface area of adultIndian elephants with reasonable accuracy and to derive a
simple and reliable prediction equation for estimating total
surface area indirectly.
MATERIALS AND METHODS
The study was conducted on 12 female and 12 male adultIndian elephants (Elephas maximus

indicus), varying in age from 18 to 60 years and in weightfrom 1880 to 5290 kg, maintained by the Temple Devaswoms,
the Forest Department of the Government of Kerala and theGemini Circus. All the animals were clinically healthy andwere maintained under an optimal nutritional regime.
The body weight, the height at the shoulders and the bodylength from the base of the forehead to the base of the tailwere recorded as described earlier (Sreekumar and Nirmalan,1989). All measurements were taken in duplicate with astrong tape measure which withstood the rough handlingwithout stretching, shrinking, curling or breaking, and theaverage value was used.
For determination of the total surface area, the elephant
was divided geometrically into differnent surface anatomical regions (Figures 1, 2, 3 and 4) and the area (m2) was
calculated for each individually. The sum total of the areasof the individual regions then gave the total surface area.

This finding was awarded the Ig Nobel prize. Also known as the Ignatius Nobel prize, is sponseredby Annals of Improbable Research, Harvard University, USA; The Harvard Computer Society, The
Harvard - Radcliff Science fiction association and the Harvard-Radcliff Society of Physics Students,
Harvard University, USA. Every year 10 prizes are given to people whose achievements shouldhave a curious property and also entice more people to become interested in science.
Dr. K.P. Sreekumar and his late Professor Dr. G. Nirmalan were honoured for their achievement in Estimating the Total Body Surface Area of Indian Elephants and for deriving asimple equation for predicting the total body surface area using height and foot circumference of elephants.
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Figure 4. Sites at which body measurements have been taken(m)P1-Perineal region base length,

Figure 1. Sites at which bodymeasurements have been taken (m):T1 - Trunk length
T2, T3, T4 - Trunk circumference
FN1 - Fronto-nasal length
FN2 - Fronto-nasal breadth
E1 - Ear base length
E2 - Ear altitude

Figure 2. Sites at which bodymeasurements have been taken (m):J1 - Jowl base length
J2 Jowl altitude

Figure 3. Sites at which body measurements have been taken (m):F1 - Face base length

HI3-Breadth between the two parallel

F2 - Face altitude

Sides of the hip

N1 - Neck length

FL1 - Forelimb length

N2,N3,N4 - Neck circumference

FL2, FL3, FL4 - Forelimb

S1-Shoulder length

circumference

S2-shoulder breadth

FFC-Fore-footpad circumference

H-Height at the shoulders

HL 1-Hindlimb Length

B1-Body length

HL2,HL3,HL4-Hindlimb

B2-B3,B4-Body circumference

circumference

HI1, HI2 - Length of the two parallel

HFC-Hind Footpad circumference
TL1 - Tail length

sides of the hip

TL2, TL3-Tail circumference
TTC-Tail tip circumference

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P2-Perineal region altitude

The trunk of the elephant was considered as a cylinder
with both ends open. The length from the central point of thetransverse line connecting the base of the two tusks (Base of
the trunk) to the tip of the trunk was taken as the length of
the trunk (T 1). The circumference was taken at threeplaces,namely the base (T2), middle (T3) and tip of the trunk(T4), and the mean of these three values was taken as thecircumference of the trunk (Figure 1)
The fronto-nasal region (front of the head) was regarded
as a rectangle; the straight line connecting the two frontolateral angles of the forehead was taken as one side and theline connecting the base of the tusks as the other side, theaverage of these two being FN1. The straight lines drawn
downwards connecting the above lines at their lateral ends
formed the other two sides, the average of these being FN2(Figure 1)
The face region (side of the head) was treated as a triangle with the straight line length from the fronto-lateralangles of the forehead to the angle of the mandible as thealtitude of the triangle (F2) and the length from the angle ofthe mandible to the level of the caudal border of the mandibular symphysis as its base (F1). The straight line connecting the caudal border of the mandibular symphysis and thefronto-lateral angle of the forehead then formed the third sideof the triangle (Figure 3)
The ear of the elphant resembled a triangle, the lengthfrom the rostral angle of the attached border to the caudal
angle of the ear forming the base (E1). The rostral border(attached border) and the caudal border joined at the free
end making the distal angle (apex). The height of the triangle was taken as the straight line length between the baseand the apex of the ear (E2) (Figure 1)
The jowl region was also considered as a triangle withthe straight line distance between the angle of the mandibles
as the base of the triangle (J1) (Figure 2). The two horizontal
rami of the mandibles which join in front at the mandibularsymphysis formed the other two sides of the triangle. The

straight line distance from the apex of the lower lip to thebase of the triangle formed the altitude of the triangle (J2).
The neck was regarded as a cylinder with both ends open
and was divided into three regions, namely, rostral, middle
and caudal. The circumference of the rostral part (N2) was
taken at the level around the neck just at the angle of themandible. The circumference of the middle region (N3) was
taken at about the level of the fourth cervical vertebra. Measurement of the caudal region (N4) was taken at the base of
the neck in front of the shoulder. The mean of these threemeasurements was taken as the circumference of the neck.
The length of the neck (N1) was taken as the length between
the rostral transverse line, just behind the mandible, and thecaudal transverse line, just in front of the shoulder (Figure
3).
The body was regared as a cylinder with both ends open
and the measurements were noted during the period of expiration at three levels - anterior, middle and posterior regions.
The anterior body girth (B2) was taken at the anterior part ofthe chest behind the transverse line connecting the externalangle of the scapula to the olecranon process (anterior transverse line). The middle girth (B3) was taken at the level ofthe eleventh rib and the posterior body girth (B4) at the region in front of the posterior transverse line connecting therostral end of the external angle of the ilium to the flap ofskin ventrally (connecting the stifle to the belly). Again themean of these three measurements was taken as the circumference of the body. The body length was taken as the distance between the anterior and posterior transverse lines (B1)
(Figure 3).
The shoulder region was regarded as a rectangle. The
perpendicular line drawn from the spine of the seventh cervical vertebra down to the level of the lower end of the middle
third of the arm formed one side and the perpendicular line
drawn from the level of the fifth thoracic vertebra down to
the level of the lower end of the middle third of the arm
formed the other side, the average of these two measurements being S1. The straight lines joining the ends of boththese sides formed the other two sides formed by the straightline connecting the dorsal angle of the ilium to the lower endof the middle third of the thigh region (HI1) and the other by
the straight line from the level of the first coccygeal vertebra
to the ischial tuberosity (HI2). These two sides formed theparallel sides of the trapezium, the distance between them
being HI3 (Figure 3).
The fore-and hindlimbs were both considered as cylinders with one end closed. The height of the forelimb (FL1)
was the distance from the lower end of the middle third of
the arm to the level of the footpad. The circumference wastaken at three places, namely, the lower end of the middle
third of the arm (FL2), just below the elbow joint (FL3) andjust below the carpal joint (FL4). The average of these threevalues was taken as the mean circumference. The height of

the hindlimb was the distance from the lower end of the
middle third of the thigh to the level of the footpad (HL1).
The circumference of the hindlimb was measured at the lower
end of the middle third of the thigh (HL2), just below thestifle joint (HL3) and just below the hock joint (HL4). The
average of these three measurements was taken as the mean
circumference of the hindlimb. Both the fore- and hind-footpads were assumed to be circular and their circumference
was taken at the base of the foot around the nails the calculated areas of the footpads (FFC and HFC) were than added
to the already calculated areas for vertical surfaces of therespective limbs to get the surface areas of the fore andhindlimbs (Figure 3).
The tail gave the appearance of a cylinder with one end
closed (the tip of the tail). The circumference of the tail was
taken at two places, these being the base (midline intersection of tuber ischii) (TL2) and the middle (TL3). The averageof these two was taken as the mean circumference. The
straight line distance from the base of the tail to the tip of thetail consituted the length (TL1). The tail tip was assumed to
be a circular figure; its circumference was measured and thecalculated area (TTC) was added to the area of the tail (Figure 3).
The perineal region was taken to be a triangle extending
from the lower end of the anal opening down the loose flapof skin lying between the thighs. The transverse line connecting the tuber ischii formed the base of the triangle (P1).
Two lines drawn from the tuber ischii connected at the apex,
so as to include the loose flap of skin in the perineal region.
The vertical length from the apex of the loose flap of skin to
the base then formed the height of the triangle (P2) (Figure
4).

Relationship between body weight (kg.) and total surface area (m2)

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Thus the total surface area of each elephant dould be derived as follows:
Area
No.
1

RegionCalcuation(lengths in m from Figures 1-4)

Trunk

T1

2
3
4
5

Fronto-nasal
Face
Ears
Jowl

6

Neck

7
8

Shoulders
Forelimbs

9

Body

T 2 + T3 + T 4

3
FN1x FN2
F1 x F2
2 (E1 x E2)(J1 x J2) /2
N1(N2 + N3 + N4)

3
2 (S1 x S2)
FFC2 + 2FL1 (FL2 + FL3 + FL4)
2
3
B (B2 + B3 + B4)
1

10
11

Hips
Hindlimbs

12

Tail

13

PerineumTotal

3
HI3 (HI1 + HI2)
HFC2 + 2HL1 (HL2 + HL3 + HL4)
2
3
TTC2 + TL1 (TL2 +TL3)
4
2(P1 x P2) /2
1
13

The areas of the face, shoulder, hip and fore-and hindlimbs
so calculated were doubled to incorporate both sides, while
for the ear the area was quadrupled, since each ear has two
surfaces.
The least square method of analysis (Snedecor andCochran, 1967) was used to assess the relationship and derive prediction equations. The standard errors of the predictedvalues (SEEM) were taken as indicators of the relative accuracy of prediction of the various formula.
RESULTS
The measured total surface area of the adult female elephants (nos. 1 to 12 in Table III) ranged from 13.56 to
21.18m2 and that of the adult male elephants (nos. 13 to 24
in table III) ranged from 12.16 to 20.97m2. To derive simple
prediction formulae, the areas of the individual regions andthe measurements for the individual regions were correlated
singly or in combination with the total surface area. In thecase of individual regions, only those areas which gave correlation coefficients of above 0.70 were considered. In thecase of individual measurements, only those giving a corre○

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lation coefficient of 0.80 and above were considered. The
optimal equations thus worked out for predicting the total
surface area of males and females or of adults irrespective ofsex from the various parameters, singly or in combination,
are shown in Table I. The most accurate prediction of total
surface area appeared to be achieved by using two parameters, namely the height at the shoulders (H) and the forefootpad circumference (FFC) (SEEM = 0.80 m2)
The accuracy of the prediction obtained using the formula s=-8.245 + 6.807H+ 7.073FFC is shown in Figure 5.
However, application of this formula was by no means entirely accurate. One male elephant having a measured surface area of 12.16 m2 was overestimated by 1.44m2 (11.84%
error) while another male having a measured surface area of
16.09 m2 was underestimated by 0.89m2 (5.50% error).The
highest overestimation in a female was 8.22% and the worst
underestimation was 8.35%.
DISCUSSION
The total surface area of an animal can be used as anindicator of its total daily heat production (basal energy metabolism) and provides a valuable aid for determining thenecessary supply of daily dietary energy. Since actual measurement of the surface area, adopting the techniques described in this paper, is strenuous and laborious under practical field conditions, a formula incorporating the exponential of the body weight, on the lines of conventional Meeh's
formula (Dukes, 1955) for predicting the total surface area
was tried. It was found that the coefficients of determination
were low (r2 = 0.5589 in males, 0.3972 in females and 0.3849
in adults irrespective of sex) and the SEEM values were alsohigh. Hence the relationship between the body weight andactual surface area (Figure 6) was widely scattered and theuse of the exponential of body weight cannot be recommended for predicting the total surface area in adult Indian
elephants. Exponential equations were also fitted incorporating height along with body weight on the lines of Dubois'
formula (Cena and Clark, 1981) but again the SEEM values
were relatively high.
When the areas of individual regions were used to derive
similar equations, relatively high correlations were obtained
between the forelimb area (FLA, r= 0.7689) and total surface area, and between the ear area (EA, r = 0.7459) andtotal surface area. Hence, these two areas were used individually and in combination, in both simple linear and multiple linear regressions. However, again the SEEM values
were high in all cases.
Individual measurements were then tried to obtain a better prediction equation. It was observed that measurements
such as the height at the shoulders (H, r=0.9234), theforefootpad circumference (FFC, r= 0.8797) and the forelimb circumference (FLC, r = 0.8062) gave correlation ratios greater than 0.8 with total surface area and hence thesewere also used to derive simple linear and multiple linearregressions (Table I). Of these simple equations involving
only one parameter, the height at the shoulders (H), had thelowest SEEM value in the case of adult males, adult females
and audlts irrespective of sex (Table II). Among the multiple
linear regressions fitted, the SEEM value was lowest in adults
irrespective of sex for the involving the height at the shoulders and the fore-footpad circumference. Although in the caseof male elephants the lowest SEEM value was that for theequation S=-10.85 + 11.86 FFC+12.13FLC involving theheight at the shoulders (H) and the forelimb circumference(FLC), the total surface areas obtained by adopting theseequations in males and females respectively were not statistically different from the results obtained by applying theformer equation. Hence, for simplicity's sake, the equation
involving the height at the shoulders and the fore-footpad
circumference is recommended for us with adult Indian elephants, irrespective of sex.
Benedict (1936) established the surface area of a single
Indian elephant as 23.8m2 using the conventional formula.
The lower mean value for surface area recorded in the present
study (Table III) can be attributed to the larger size of thesample as well as to the use of a better predictor.
Table IIIThe measured and estimated surface area (mean + SE)
using the recommended formula in 24 adult Indian elephants
irrespective of sex.
Elephant
MeauredEstimated surface area (m2)no.
surface area S=-8.245 + 6.807H + 7.073FFC
1
17.17
16.73
2
17.22
17.55
3
17.21
16.46
4
17.74
16.58
5
18.17
18.31
6
15.33
16.59
7
13.56
13.69
8
17.72
16.24
9
21.18
21.42
10
16.06
16.21
11
19.51
18.63
12
16.44
16.58
13
12.90
13.83
14
12.16
13.60
15
17.60
16.79
16
18.03
18.65
17
20.97
20.70
18
17.91
18.31
19
16.09
15.20
20
19.40
19.33
21
17.90
18.65
22
15.30
14.65
23
19.05
19.68
24
17.75
17.97
Mean + SE 17.18+0.46
17.18+0.43

S=Total surface area (m2)
H=Height at the shoulders (m)FFC = Fore-footpad circumference (m)ACKNOWLEDGEMENTS
We are grateful to Dr. B.C Joshi of the Division of Physiology and Climatology, Indian Veterinary Research Institute,Izatnagar, for his constructive criticism of the methodology
adopted.
Our sincere thanks are due to Sri. N. Madhavan Pillai,
Chief conservator of Forests (Wildlife); Dr. P Girinathan Nair,
Forest Veterinary Officer; Dr. Ramanujam, Veterinary Officer Of Guruvayoor Devaswom and Mr. Shanker, Managing Partner, Gemini Circus for making available the elephants
for the study.
The encouragement given by Dr. K. Radhakrishnan, Dean
and Dr. M. Krishnan Nair, Director of Veterinary Researchand Education, is acknowledged with pleasure.
We recollect with gratitude the immense help extended
by Dr. P.A.Ommer, Dr. J.J. Chungath, Dr.C.B. Devandand,
Mr. K.L.Sunny, Mrs. K.P..Shanthabai and Miss U.Geetha,
members of the faculty, Kerala Agricultural University.
We are indebted to Dr. C.J. Xavier, Veterinary Surgeon;
Sri. K.K. Radhakrishnan and Sri. Madhu Rajan Mathews,
students of this Institute for their assistance in recording themeasurements and drawing the diagrams.
REFERENCES
Benedict, F.G. 1936 . The Physiology of the Elephant(Carnegie Institute, Washington)
Cena, K. and Clark, J.A., 1981. Bioengineering, Thermal Physiology and Comfort (Elsevier Scientific Publishing
Company, New York)
Dale, H.E., 1984 Energy metabolism. In: M.J. Swenson(ed.), Duke's Physilogy of Domestic Animals, 10th end.
(Comstock Publishing Associates, Cornell University Press,
London)Dukes, H.H., 1955. The Physiology of Domestic Animals, 7th edn. (Bailiere, Tindall and Cox, London)
Snedecor, G.W. and Cochran, W.G., 1967. Statistical
Methods (Oxford & IBH Publishing Co., Calcutta)
Sreekumar, K.P. and Nirmalan, G., 1989. Estimation ofbody weight in Indian elephants (Elephas maximus indicus).
Veterinary Research Communications, 13,3-9(Accepted:24 October 1989) o

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