First report of gray whale (Eschrichtius robustus, Lilljeborg, 1861) conjoined twin calves in the Eastern Pacific Ocean

Abstract

In January 2014, gray whale (Eschrichtius robustus) conjoined twin calves were found dead in Laguna Ojo de Liebre (Scammon’s Lagoon), Baja California Sur, Mexico. The thoracopagus (united ventrally at the chest) individuals were conjoined in the thorax region, sharing the navel and genital area, but with two distinct heads and flukes. Although observed in humans and domestic animals, this case is rare among cetaceans. Some conjoined twin cetacean fetuses have previously been reported; however, this is the first report of the congenital anomaly in Eschrichtius robustus.