Evaluation of Siamese Twins of Testudo graeca Linnaeus, 1758

Abstract

Objective: In the present study, the morphological features of common tortoise (Testudo graeca Linnaeus, 1758) found in the Pamukkale ruins and determined to be two-headed Siamese twins, were investigated using computed tomography. Material and Methods: The size and weight of the twin tortoise were measured and placed under care in a terrarium similar to their natural habitat. The anatomical features of the two headed Siamese twins were evaluated by three-dimensional volumetric computed tomography. Results: The Siamese twins combined from the end of the shell have 4 anterior extremities and 2 posterior extremities. Even though tortoises were conjoined, they were reacting independently, but had to move together due to their abnormal shell structures. The Siamese twins weighed 13.2 grams when they were found. They survived 47 days in the terrarium. The tomography scanning showed that that one of the twins was fused from the 7th vertebrae and the other from the 8th vertebrae. Although the internal organ structure is not clear, it has been observed that they use a shared cloaca. Conclusion: The anomalies rarely seen in reptiles can be caused by many factors, including environmental and genetic factors.

Keywords

• Anatomy
• Computed tomography
• Common tortoise
• Pamukkale ruins
• Siamese twins

References

1. Barbour, E. H. (1888). On a young tortoise, Chrysemys picta, with two heads.The American Journal of Science [third series.] Vol. XXXVI, No. 214.--OCT., 1888, pp. 227-230 & Plate V. google scholar
2. Başoğlu, M., & Baran, İ. (1977). Türkiye Sürüngenleri Kısım I. Kaplumbağa ve Kertenkeleler. Ege Üniversitesi Fen Fakültesi Kitaplar Serisi, 76, 272 pp. google scholar
3. Cooper, J. E. (2009). Conjoined (“Siamese”) twins of the leopard tortoise (Geochelone pardalis), with a plea for documentation of such abnormalities in reptiles. Journal of Herpetological Medicine and Surgery, 19(3), 69-71. google scholar
4. Dabin, W., Cesarini, C., Clemenceau, I., Dhermain, F., Jauniaux, T., Van Canneyt, O., & Ridoux, V. (2004). Double-faced monster in the bottlenosed dolphin (Tursiops truncatus) found in the Mediterranean sea. Veterinary Record: Journal of the British Veterinary Association, 154(10). google scholar
5. De Silva, A., Bandaranayake, R., & Karunarathna, S. (2020) Note on a case of congenital twinning of the star tortoise (Geochelone elegans) in Sri Lanka, Radiata 29 (4). google scholar
6. Dimitropoulos, A. (1985). A case of living twins in a single egg of the Marginated tortoise, (Testudo marginata Schoepff, 1792) in a clutch taken from the wild. Herptile 10(3):79-80. google scholar
7. Eckert, K. L. (1990). Twinning in leatherback sea turtle (Dermochelys coriacea) embryos. Journal of Herpetology, 24(3), 317-320. google scholar
8. Edwards, G.. (1751). A Natural History of Birds, Part IV, p. 206. google scholar

9. Harkewicz, K. A. (2002). Prolapse of the penis in a pair of cojoined twin male Hermanns tortoises (Testudo hermanni spp.). In Proceedings of the Association of Reptilian Amphibian Veterinarians Conference, Reno. google scholar
10. Hildebrand, S. F. (1938). Twinning in turtles. Journal of Heredity, 29(7), 243-254. google scholar
11. Hiraga, T. & Dennis, S. M. (1993). Congenital duplication. Veterinary clinics of North America: Food animal practice, 9(1), 145-161. google scholar
12. Molina, F. B., Farias, E. C. & Gomes, N. M. B. (1996). Case of twinning in the d’ORBIGNY’s slides, Trachemys dorbigni (Testudines, Emydidae). Bulletin of Chicago Herpetological Society, 31(8), 145-6. google scholar
13. Mostafa, M. B., Koma, K. L. M. K. & Acon, J. (2005). Conjoined twin piglets. The Veterinary Record, 156(24), 779. google scholar
14. Newman, H. H. (1917). The biology of twins (mammals). University of Chicago Press. google scholar
15. Newman, H. H. (1923). The physiology of twinning. University of Chicago Press, Chicago, 1923, 230 pp., 71 figs. google scholar
16. Pereira, R. & Rocha, S. (2004). Chioglossa lusitanica (golden-striped salamander): Dicephalic larva. Herpetological Bulletin, (87), 29-30. google scholar
17. Sönmez, B., Sert, M., Kayikçi, S., Bedirci, Ö., & Özdilek, Ş. Y. (2017). A two-headed green sea turtle (Chelonia mydas) hatchling on Samandağ beach, Turkey. Russian Journal of Herpetology, 24(2), 158-162. google scholar
18. Stockard, C. R. (1921). Developmental rate and structural expression: an experimental study of twins,‘double monsters’ and single deformities, and the interaction among embryonic organs during their origin and development. American Journal of Anatomy, 28(2), 115-277. google scholar
19. Tiar-Saadi, M., Tiar, G., Bouslama, Z., & Siroky, P (2022). Mechanisms Determining Body Size and Shape Difference in Algerian Spur-Thighed Tortoises (Testudo graeca). Animals, 12(10), 1330. google scholar
20. Tucker, J. K. (1996). Two examples of twinning in the red-eared slider (Trachemys scripta elegans). Bull. Chicago Herp. Soc. 31, 41-43. google scholar
21. Tucker, J. K. & Janzen, F. J. (1997). Incidence of twinning in turtles. Copeia, 166-173. google scholar
22. Tucker, J. K., and R. S. Funk. 1976. Twinning in the Gulf Coast box turtle, Terrapene carolina major. Florida Scientist 39:238-239. google scholar
23. Velo-Ant6n, G. Becker, C. G. & Cordero-Rivera, A. (2011). Turtle carapace anomalies: the roles of genetic diversity and environment. PLoS One, 6(4), e18714. google scholar
24. Yntema, C. L. (1970). Twinning in the common snapping turtle, Chelydra serpentina. The Anatomical Record, 166(3), 491-497. google scholar