Torpedo rays

Abstract: Edward Bancroft was a medical apprentice in Connecticut before running off to Guiana in 1763. While in South America, he practiced medicine and collected material for a lengthy book on the region, which he published after he settled in London. Bancroft’s Essay (1769) contains a description of the “torporific eels” found in the warm rivers of Guiana, along with a series of experiments suggesting that the eel’s powers are electrical. It also calls for studies to determine whether saltwater torpedo rays might demonstrate the same properties, which Bancroft expected would be the case. Today, Bancroft is best remembered for serving Benjamin Franklin and the American delegation in France during the War of Independence, and for being a double agent. But what this colorful man wrote about the South American eels helped to make an early case for animal electricity and stimulated Franklin to encourage John Walsh to conduct his landmark electrical experiments on torpedoes and electric eels in the 1770s. These efforts led to new way of thinking about the physiology of the nervous and muscular systems, even in nonspecialized fish.

Abstract: The early history of neurophysiology has two important roots. The earlier of the two involves various ideas about invisible animal spirits traversing the nerves. The other, which emerged during the eighteenth century, is based on the idea that the elusive spirits are electrical—that animal electricity really does exist. The latter idea stemmed in part from what was being discovered about three types of electric fishes and their shocks prior to Galvani’s broader claim in 1791 for animal electricity. This contribution focuses on how the shocks of each of these fishes had been described by three writers outside the fields of physiology and medicine: Plato, the well-known Greek philosopher, who actually provided the first good description of the powers of torpedo rays; Aphra Behn, a leading English Restoration playwright and novelist, who introduced many English speakers to the creature that would become best known as the “electric eel”; and Michel Adanson, a French botanist, who seemed to be the first to compare albeit the electric catfish’s shocks to those from a known source of electricity, a Leyden jar. All three authors were famous in their day, and all played important roles in the history of biological electricity by making others aware of one of Nature’s wonders, fishes that could “torpify,” even without direct contact.