Anatomical, Histological, and Molecular Characterization of the Venom of Squalus acanthias and Heterodontus francisci

Chondrichthyian fishes are collectively known to include many venomous taxa, but most of what is known about both the venom molecules and delivery apparatuses in this group comes from studies of the batoids. The distribution pattern and content of venoms found in either the chimaeras or sharks subgroups have never been documented and remain poorly understood. Within sharks the taxonomic families Squalidae, Etmopteridae, and Heterodontidae are known to possess fin spines that could be potentially venomous. Here, histological examination of fin spine tissues and basic biochemical and toxinological analyses of fin spine extracts from several specimens of Squalus acanthias and Heterodontus francisci are used to both confirm the presence of and provide a basic description of the venom in these groups.