Vertebral pattern variation in the North Sea harbor porpoise (Phocoena phocoena) by computed tomography

Abstract

Vertebral series in the harbor porpoise (Phocoena phocoena) include cervical, thoracic, lumbar, and caudal. In contrast to studying skeletons from museums, in which small bones can be missed, evaluation of full body computed tomography (CT) scans provides an overview of the vertebral column, while maintaining interrelationship of all structures. The aim of this study was to document variations in vertebral patterning of the harbor porpoise via evaluation of CT images of intact stranded harbor porpoises. The harbor porpoises were divided into age classes, based on developmental stage of reproductive organs on postmortem examination and closure of proximal humeral physis on CT. Numbers of vertebrae per series, fusion state of the syncervical, type of first hemal arch, number of double articulating ribs, and floating ribs were recorded based on CT images. Included in the study were 48 harbor porpoises (27 males and 21 females), which were divided in two age classes (27 immatures and 21 adults). Total vertebral count varied from 63 to 68 with vertebral formula range C7T12‐14L12‐16Cd29‐33. Twenty‐five different vertebral formulas were found, of which C7T13L14Ca30 was the most common (n = 8, 17%). Thoracic vertebrae with six, seven, or eight double articulating ribs and zero, one, or two vertebrae with floating ribs were seen. Four different fusion states of the syncervical and four types of hemal arches were recognized. This study showed a great variation in vertebral patterning in the harbor porpoise, with homeotic and meristic variation in the thoracic, lumbar, and caudal vertebral series.

What a Stranded Whale With Scoliosis Can Teach us About Human Idiopathic Scoliosis

“…Harbour porpoises are regularly subjected to post mortem examination and in a previous study focusing on their anatomy, animals were subjected for full-body CT-scan prior to the necropsies. 44 Ten cases which did not present spinal abnormalities and were positioned straight during CT-scanning were selected from this database and used as a control group in this study.…”

Post-Mortem Computed Tomography Pulmonary Findings in Harbor Porpoises (Phocoena phocoena)

“…PMCT evaluation has successfully been used in the detailed description of anatomical skeletal features of the harbor porpoise vertebral column and skeletal and ear pathology in several cases [ 18 , 19 , 20 ]. However, pulmonary changes have not been systematically evaluated.…”

Cetaceans Humerus Radiodensity by CT: A Useful Technique Differentiating between Species, Ecophysiology, and Age

“…Cetaceans are mammals that underwent a series of evolutionary adaptations to live in the aquatic environment [ 1 ], including morphological modifications of various anatomical structures of the skeleton and their bone density [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. However, there are few studies on the latter.…”