Malformations of the sacculus and the semicircular canals in spider morph pythons

Abstract

Spider morph ball pythons are a frequently bred design morph with striking alterations of the skin color pattern. We created high resolution µCT-image series through the otical region of the skulls, used 3D-reconstruction software for rendering anatomical models, and compare the anatomy of the semicircular ducts, sacculus and ampullae of wildtype Python regius (ball python) with spider morph snakes. All spider morph snakes showed the wobble condition. We describe the inner ear structures in wild-type and spider-morph snakes and report a deviant morphology of semicircular canals, ampullae and sacculus in spider morph snakes. We also report about associated differences in the desmal skull bones of spider morph snakes. The spider morph snakes were characterized by wider semicircular canals, anatomically poorly defined ampulla, a deformed crus communis and a small sacculus, with a highly deviant x-ray morphology as compared to wildtype individuals. We observed considerable intra- and interindividual variability of these features. This deviant morphology of spider morph snakes can easily be associated with an impairment of sense of equilibrium and the observed neurological wobble condition. Limitations in sample size prevent statistical analyses, but the anatomical evidence is strong enough to support an association between the wobble condition in design bread spider morph snakes and a malformation of the inner ear structures. A link between artificially selected alterations in pattern and specific color design with neural-crest associated developmental malformations of the statoacoustic organ as known from other vertebrates is discussed.

Comparative assessment of computed tomography and magnetic resonance imaging of the spider morph of Python regius and wild type Python regius to evaluate the morphological correlate of the wobble syndrome

“…Since all five spider ball pythons included in this study exhibited the wobble syndrome in differing degree and specific symptoms and showed similar morphological anomalies, namely malformation of the saccule (Starck et al submitted) and the inner ear, it is highly probable that these alterations are the cause of the wobble syndrome. These findings need to be further verified by larger sample size and of high-resolution imaging like μ-CT and / or histology.…”