Morphological aspects and composition of African elephant (Loxodonta africana) ivory

Abstract

This study was aimed at determining the origin of the diamond shaped pattern and composition of ivory of the African elephant. Fragments of ivory and tusks were obtained through the National Parks Board from the Kruger Park, Addo Elephant Park, Kaokoveld, Caprivi, Etosha, Kavango and Tembe Elephant Park. Polished surfaces were prepared in different planes and examined with light and electron microscopical techniques. Analyses of the inorganic composition were performed using atomic absorption spectrophotometry, ion selective electrodes and inductively coupled optical emission spectroscopy. The total amino acid composition was determined with the aid of an amino acid analyser. Morphological investigations showed the distinctive diamond shaped pattern of ivory to be caused by the sinusoidal surface to pulpal course followed by odontoblastic tubules. This course is the result of pressure which builds up between tightly packed odontoblasts on their centripetal course along an ever decreasing pulpal circumference during formation of ivory. A total of 17 elements were detected in the inorganic fraction of ivory, some in concentrations as low as 0.25 ^g/g. The concentrations of calcium, magnesium, fluoride, cobalt and zinc showed statistically significant differences (P < 0.007) between selected regions and may prove valuable in distinguishing chemically between ivory from different geographical locations. The organic content of ivory showed 17 amino acids in varying concentrations. The possible causes of these variations are discussed.