standardization of records keeping in indian zoos - Central Zoo ...

8.3 Natural Differences
The most common and straightforward method of identifying individual
elasmobranchs is to take note of natural differences in coloration, markings, size,
and/or sex (Ellis, pers. com.; Lewand, pers.com.; Smith, pers. com.; Violetta, pers.
com.). This technique is particularly effective with species of a mottled, spotted, or
otherwise non-uniform coloration. For example, sand tiger (Carchariastaurus),
broadnose sevengill (Notorynchuscepedianus), and white tip reef (Triaenodonobesus)
sharks can often be distinguished by thedistribution of darker spots on their bodies.
The shape of dorsal fins, and notches or scars thereon, have been used to identify
individual white sharks (Carcharodon carcharias) in the wild(Klimley and Ainley,
1998).Relative size differences between individuals may become less obvious as
animals grow. However, it is unusual for an individual within a collection to
completely change its size ranking relative to other members of the group. Of course a
medical condition that affects appetite or food assimilation may change this equation.
Behavioral differences may be used as natural identification technique. Janse (pers.
com.) has noted a clear and reliable difference in the feeding behavior of two
individual blacktip sharks(Carcharhinus limbatus). Individual animals may
consistently choose a specific area of an exhibit to swim and/or rest, or have distinctly
different behavior toward the presence of divers.The skin pigmentation of some
elasmobranch species is patterned, variations of which arecharacteristic to individuals.
The arrangement of white spots on spotted eagle rays (Aetobatusnarinari),
particularly around the base of the tail, is distinctive for each individual (Gruber, pers.
com.).These patterns are similar to human fingerprints in the sense that they are
unique and do not changeover time. Photo-identification of individual animals, as has
been used in cetacea for many years, has recently been employed in elasmobranchs
(Gruber,pers. com.). Firchau (pers. com.) has successfully used photo-identification to
distinguish between individual chain dogfish (Scyliorhinus retifer). The chain-like
patterns are characteristic for each individual, with the most distinctive differences
occurring in the bands on the dorsal part of the head and the pectoral region
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