The unicorn ray: a morphological abnormality in a southern eagle ray (Myliobatis tenuicaudatus)

We document a unique dorsal protrusion of a southern eagle ray (Myliobatis tenuicaudatus) by-caught in a trawler off the coast of New South Wales, Australia. Radiological imaging led us to conclude the abnormality is a congenital defect that resulted in a pair of additional pelvic fins growing on the dorsal surface. It is unlikely the abnormality had substantial impact on the growth and survival of the animal since it had grown substantially since birth and there was minimal impact to structures that facilitate the movement required to forage and evade predators.