Abnormal blacktip shark, Carcharhinus limbatus, embryo from the northern Gulf of Mexico

Teratological phenomena have been reported from a range of fish taxa; however, among chondrichthyans such observations are rare (Laale and Lerner, 1981; Heupel et al., 1999), particularly for embryos. The first record of a deformed elasmobranch is attributable to Aldrovandi, who in 1642 described a dicephalic shark embryo (Gudger, 1936). Since then, infrequent reports of deformed shark embryos have occurred in the literature including cases of cyclopia, dicephally and skeletal anomalies (e.g. Dean, 1923; Abe, 1972; Escobar-Sa' nchez et al., 2009). Because of the rarity of such cases, reported herein is the collection of a severely deformed blacktip shark, Carcharhinus limbatus (Mueller and Henle, 1839), embryo from the northern Gulf of Mexico.