Abstract

Kyphosis is a spinal column defect that produces a hunched-back phenotype and is 1 of the most distinctive and often reported shell anomalies in turtles. I compiled records of the occurrence of kyphosis in turtles from the literature, from personal communications with colleagues, and my own unpublished data. This effort resulted in 568 records from 188 studies representing 10 of 14 families, 37 of 97 recognized genera (38%), and 71 of 357 species (20%). For reports that provided population sample sizes, 501 of 280,382 individual turtles (0.18%) were kyphotic. Kyphosis has been reported in only 6 of 96 (6%) recognized pleurodiran species compared to 64 of 261 (24%) recognized cryptodiran species, but this difference may reflect failure to record data rather than a difference associated with phylogenetic divergence. Reports of kyphosis are most frequent among trionychids and podocnemids, more common among females than males, and more common in species with genetic sex determination versus temperature-dependent sex determination; correlation with latitude may exist in some species. This deformity is well documented in embryos, hatchlings, and juveniles, indicating a typical embryonic origin; however, posthatching development of kyphosis following traumatic boat strike injury has also been reported. Surprisingly, the impacts of kyphosis on individual fitness seem to be minimal. Of the many potential factors proposed to explain the etiology of kyphosis in turtles, the most probable appear to be extreme environmental conditions (especially incubation temperature and pollutants) during midincubation, when they might interfere with normal developmental rates.