The Mustelus canis shark, often referred to as the smooth dogfish, skulks from the edge of New England to the Gulf of Mexico, off the coast of Brazil and along the shores of northern Argentina. It is not native to the ocean-blue seats of a New York subway train. But there it was found on Wednesday, just after midnight, deceased beneath a subway bench, as passengers braved a stench that, even by the standards of public transport, might have driven them away under ordinary circumstances. Brandon Sanchez, 20, noticed the shark, about a metre long, through a window as the train arrived at Canal Street. He stepped in with a friend, snapped a picture, and left to board a neighbouring carriage. He did not bother mentioning the shark to subway staff. "I thought eventually they would find out there was a shark on the train," he said. And they did, a dozen stations later, at Queensboro Plaza, when a conductor called in a report for which there is no transit code: there was a shark in Car 8994. When the train reached Astoria/Ditmars Boulevard, a supervisor pronounced the animal dead, placed it in a rubbish bag and threw it away. By that time, according to photos published on the website Gothamist, it had acquired a can of Red Bull energy drink, a MetroCard and a cigarette in its mouth. The Metropolitan Transportation Authority said it was unclear how the shark had reached the transit system. Inquiring riders were left to hazard their own theories. Was it vanquished in the Darwinian wilderness of New York City Transit, where rats are small in stature, but large in numbers? Had it escaped from Chinatown, where shark-fin soup remains a staple? More cynical travellers observed that the animal had been found during Discovery Channel's "Shark Week", surmising that its appearance may have been a marketing ploy. The channel bristled at the implication. "It deeply saddens us someone would think this was funny or in any way connected to our celebration of sharks," spokeswoman Laurie Goldberg said. Despite the smell, passengers deemed the sighting the highlight of their transit careers. "I've seen a homeless man with his pants down," Sanchez recalled. "I would say that this beats that."