Deviations in the Development of Captivity Walrus (Odobenus rosmarus) Skull

Abstract

Currently, many aquariums and zoos around the world keep walruses in captivity. However, the presence of tusks in walruses creates difficulties in their maintenance and preservation of their health since they wear them down on the structure of the pools. In this study, the morphometric parameters of walrus skulls from captivity and wild of similar age were examined (35 skull measurements and 21 mandible measurements were taken). An examination of the skulls of three female walruses that were kept in the Moscow Zoo for 8, 11, and 22 years, respectively during the period of 1953–2005 was conducted. The tusks of one walrus, at the age of 4 years, were surgically removed, while the tusks of the others were not. There were slight deviations in the skull development of these walruses. The skull of captive walruses is slightly smaller in the mastoid processes and zygomatic arches, and facial part, and the lower jaw is smaller in width and symphysis circumference compared to wild walruses. The surface of the skull and lower jaw is smoother in comparison to wild walruses. Diseases such as odontogenic osteomyelitis, pulpitis, periodontitis, dental calculus and caries are observed. Due to frequent inflammations and surgical interventions, early fusion of sutures is noted, leading to skull deformities.