 Nursehounds are generally harmless to humans.However, 19th-century British naturalist Jonathan Couch noted that "although not so formidable with its teeth as many other sharks, this fish is well able to defend itself from an enemy.When seized it throws its body round the arm that holds it, and by a contractile and reversed action of its body grates over the surface of its enemy with the rugged spines of its skin, like a rasp.