The name Interactive Individual Identification System explains most of I³S' functionality. I³S is interactive and it is meant to support not to replace the researcher. Initially, the user has to point out the most distinguishing features (i.e. the spots and reference features, e.g. fins) of the unknown individual. In the next step, I³S assists the user in the tedious task of matching the (shark) image with a collection of images of known sharks. Results are shown as a ranked list. The user will always be responsible for making the final match between the unknown image and an image from the database.

During a shark diving course in South Africa, under supervision of Vic Peddemors and Anna Mieke van Tienhoven, the first ideas for I³S where developed. The course was combined with actual research on the impact of scuba diving on the behaviour of the group of Ragged Tooth Sharks (Carcharias taurus). The Ragged Tooth Shark, also known as the Grey Nurse or SandTiger Shark is a large brown shark with distinct spots or pigment marks on the flanks. This research was done over several years at Aliwal Shoal, a submerged sandstone reef approximately 40 km south of the city of Durban on the KwaZulu-Natal coast of South Africa. During the dives size, sex and other distinguishing features of the sharks had to be registered. After each dive all data was collected by Mieke who then tried to translate these features to individual sharks. Mieke herself was using an underwater camera. By means of the photos she also used the spot patterns on the shark's flanks to match the 'catch of the day' manually with a database of over 200 individuals. Obviously this is a time consuming job which becomes harder with each new shark added to the database.

Each shark has its own unique spot pattern and, provided that someone annotates their location, it should be possible to compare sharks automatically. During the Christmas holiday of 2003, prototype development started. In the spring of 2004 the first tests began and immediately the tool proved to be useful with high scores of reliability. In the meantime, I³S has also been proven successful in helping identifying Whale Sharks on the West coast of Australia and in southern Mozambique.