Barry removed several vertebrae from the shark’s cartilaginous spine (like all sharks, great whites have no true bones). He wiped one clean and held it up. “See the rings? Those are growth rings that we use to age sharks, just like rings in the trunk of a tree. In white sharks we are only just starting to understand which ones to count to give their age in years. We think female white sharks start breeding when they’re about 12 to 14 years old.”

To reach the heart, Barry had to actually climb inside the body cavity of the shark, and the image proved irresistible to everyone with a camera, myself included.

Pores on the shark’s snout were oozing what looked like jelly, and I asked Barry what it was. “Those are the famous ampullae,” he said, referring to the ampullae of Lorenzini, named after the Italian scientist who first described them in the 1670s. By detecting bioelectric impulses in the water, these jelly-filled canals are among the most important of the shark’s sensory organs.

Much of the shark was reduced to reeking flesh and bloody cartilage, but the head remained intact, staring implacably, a constant reminder of what it once had been.

I needed no reminder, for still fresh in my mind were images I had seen the day before, postmortem photographs of a young man killed by a great white shark the previous June, close to shore, in a little bay on an island in the Neptunes, where he and a pal had been snorkeling for abalone. The shark had bitten him only once, severing arteries in a leg and an arm, and the man had bled to death.

“Obviously the shark didn’t want to eat him,” the man who had the pictures told me. “It bit down, had a taste, and let him go. It knew this wasn’t its normal prey.”

This episode seems to reinforce a hypothesis proposed by A. Peter Klimley, a shark expert at the Bodega Marine Laboratory in Bodega Bay, California. He holds that great white sharks have an ability to assess the energy value of prey in the microsecond of a first bite. If the prey is perceived as not containing enough energy value to justify the energy expended in a full-scale attack, the shark releases it; if, however, the prey is perceived as being rich in fat (a seal, say, or a sea lion), the shark will pursue the attack. It will deliver a first, devastating bite and wait for the prey to bleed to death, then partake of a leisurely meal.

“If they ingest something that’s not energetically profitable,” Klimley says, “they’re stuck with that for a few days. Fat has twice the energy value of muscle.”

Rodney, for one, believes wholeheartedly in the idea. “The shark spat me out, didn’t he?” he says. “I was too bony for him.”

Over the past few decades the number of great white shark attacks worldwide has increased steadily, according to the International Shark Attack File. This is at least partly because more people (divers, surfers, swimmers) are using the water.