Sessions

The ostrich (Struthio camelus) and the cassowary (Casuarius casuarius) belong to the ratites, an ancient group of birds characterized by their large body size and unique survival strategies. Ostriches and cassowaries hold considerable economic and agricultural importance. Ostriches are primarily used in agriculture for their meat, leather, and feathers while cassowaries play an important role in ecological and cultural contexts, despite having no direct history of domestication. They are among the few bird species, where the male has an intromittent organ. Comparing their reproductive anatomy, particularly their phallic structures, provides valuable insights into the evolutionary differences between domesticated and wild ratites.

The aim of this study was to obtain new data on the anatomy of the phallus in ostriches and cassowaries through morphometric analyses. Six fresh, refrigerated phalli (provided by a registered slaughterhouse) were examined in this study: one adult ostrich, four juvenile ostriches and one adult cassowary. The organs were dissected, photographed, and then the length, circumference, depth of sulcus phalli, basal folds, and ventrolateral openings measured based on well-defined anatomical landmarks.

The results show clear species-specific differences. The adult ostrich phallus reached a dorsal length of 25.8 cm, approximately three times longer than that of the cassowary (8.7 cm). Similarly, the basal circumference was significantly greater in the ostrich (18.0 cm) compared to the cassowary (12.3 cm). The groove depth reached 2.7 cm in the adult ostrich, compared to 1.7 cm in the cassowary, which may indicate a greater sperm transport capacity. The juvenile ostriches showed smaller dimensions, with a dorsal length of 4.2 ± 1.5 cm and a ventral length of 3.6 ± 0.9 cm, however the same general morphological features were already present. Furthermore, the ostrich phallus tapered less distally, suggesting increased stability. The asymmetry of the ventral openings was also prominent on the right side in juvenile ostriches and cassowaries, however in the adult ostrich they showed almost symmetry. This could indicate a developmental pattern in which morphology stabilizes during maturation.

The results highlight potential developmental and functional differences, contributing to the understanding of the reproductive biology of ratites. Furthermore, the data has practical relevance for breeding management, veterinary medicine, and species conservation.