Torpedo! Odd fish is a shocker
SANDWICH — The dog yelped and pulled back, lifting one paw then putting it down gingerly as he limped away. The dog's owner walked to the edge of Fisherman's Landing and peered into the shallow water to see the source of the pain.
It was something that she'd never seen before: a flat skatelike fish, about 2 feet across and 3 feet long, but round like a dish, kind of lumpy with a broad fan at the end of a long tail.
The dog walker at Thornton Burgess Society's East Sandwich Game Farm called over staff members and a seventh-grade class from Henry T. Wing School in Sandwich, said Mary Beers, the Thornton Burgess education director.
"It stopped the staff in their tracks," Beers said. "They've been working there for years and never saw anything like it."
From a cellphone photo, Diane Murphy, fisheries and aquaculture specialist with the Cape Cod Cooperative Extension Service, identified it as an American torpedo, an electrified ray fish.
American torpedoes use specialized kidney-shaped organs on either side of their enlarged pectoral fins to deliver a shock of up to 220 volts to stun prey and discourage or harm predators and the curious.
A curious Thornton Burgess staff member did touch the ray Monday without getting shocked, Beers said. There was no sign of it on subsequent field trips.
"It can give you a hell of a belt if you stepped on it," said Dale Leavitt, an associate professor specializing in aquaculture at Roger Williams University in Bristol, R.I. "It would be good if people realized what they are."
According to Leavitt, who also identified the fish from a photo, American torpedoes are relatively common in Narragansett Bay. They typically are found at depths between 7 and 2,625 feet, migrate long distances, but are rarely seen in the shallows around here. One was found dead in Wellfleet in 2008.
Atlantic torpedoes can grow up to 6 feet in length and weigh nearly 200 pounds. They feed on large fish and smaller sharks, wrapping them in their pectoral wings and stunning or killing them with a big electrical discharge.
They have been found as far north as Nova Scotia and as far south as Brazil, but are also common in the Mediterranean and eastern Atlantic. Scientists believe rays have two types of shocks, a weaker warning discharge that can shoot upward, and the higher voltage shock they use on prey. Because of their shock potential, they have few natural enemies, according to the Florida Museum of Natural History website.
The organs that produce electricity are modified gills that are one-sixth the total weight of the animal. Researchers describe the shock as being like getting hit with a fist. While the torpedo could disable and disorient a swimmer or diver, their electric charge, which ranges from 170 to 220 volts, would be unlikely to lead to cardiac arrest or ventricular fibrillation in humans, according to the Florida museum website. In fact, the electrical discharges by these rays were once used by Romans and Greeks to treat gout, headaches and even as an anesthetic to dull the pain of childbirth.
According to the ReefQuest Centre for Shark Research website, the Greek word for these rays is narke, or "numbness," and is one root form of the word narcotic.