Martina Đuras Gomerčić: Growth, sexual dimorphism and morphometrical characteristics of bottlenose dolphin (Tursiops truncatus Montagu, 1821) from the Adriatic Sea. Dissertation. Faculty of Veterinary Medicine University of Zagreb. Zagreb. 2006.

Abstract

The bottlenose dolphin {Tursiops tnmcatus) is the only marine mammal resident in the Adriatic Sea. The morphology of this species, protected by low, is little known. This study includes 84 bottlenose dolphins found dead in the Croatian part of the Adriatic Sea. Based on the analysis of their body mass and 175 external and skeletal measurements the relationship of their morphometrical values to age and gender was determinate. Compared to other bottlenose dolphin populations geographical variation was examined. In both males and females, most growth occurs during the first nine years. In females, length reaches a plateau during the I0^lh and 12^th year of life, while in males the length increases continuously thereafter. In females, the body mass increases in a continuously process whereas in males mass increases rapidly during the I0^lh and 17^lh year of life. By the time of five years of life all bones of the skull are fused beside the nasal bones which can stay unfused also in older animals. The most growth of skull bones occurs during the first seven years of life. All neural arches are fused to the centra till the end of the first year of life. The most growth of the height and width of centra and neural processes occurs during the first seven years of life, while the length of the centra reaches adult dimensions afler the 13^lh year of life. The cranial and caudal vertebral epiphyses are fused in most animals older then 14 years. The most growth of ribs and manubrium occurs during the first seven years of life. The scapula decreases in growth after the 10^lh year of life while the humerus, radius and ulna after the 7^th year of life. The pelvic rudiment increases in length continuously and reaches adult dimensions after the 12^l year of life. In the bottlenose dolphin the growth of most external and skeletal measurements with age is well defined by the Gompertz growth curve. In bottlenose dolphins with unknown body length and mass these values can be estimated based on some external and skeletal measurements. The body length ean be best estimated based on the height of scapula, while the body mass on the girth at the anus. Sexual dimorphism is present in 32 skeletal measurements. For males the total length and body girths are greater. In the Adriatic Sea there is only one morphological type of bottlenose dolphins which is most similar to the bottlenose dolphin form the seas around China.