Brutus with a bull shark between its jaws on the Adelaide River in the Kakadu National Park. Photo: Andrew Paice/Getty Images

That Indo-Pacific crocodiles are occasional mariners is well established. The historical range of this biggest living reptile is a vast ocean-dominated kingdom: from the seacoast of southern China (where it was wiped out long ago) and the Sundarbans mangal of India and Bangladesh, south to northern Australia, and from the Solomon Islands and Vanuatu in the east as far west as the Seychelles, where it was killed off by the early 1800s. In some areas, estuarine or marine prey like crabs, stingrays and sea turtles may compose most of the diet of coastal alligators. CROCS & SHARKS Animal Face-Off-style sensationalism aside, shark-crocodile relations can usually be summarised pretty mundanely: big crocs eat little sharks and big sharks eat little crocs. The estuaries and lagoons of the tropics, after all, find the vulnerable young of both creatures overlapping. The shark pups of mangrove nurseries make easy meals for crocodiles, and hatchling and subadult crocs are appealing morsels for river-cruising sharks. That Indo-Pacific crocodiles are occasional mariners is well established. The historical range of this biggest living reptile is a vast ocean-dominated kingdom.” Indo-Pacific crocodile distribution – including the range of "wanderer" crocs – based on a map by Adam Britton.In recent years, a few crocs – likely drifters from Cuba, which has more American crocs than anywhere else – have reared their snaggletooth heads in the Cayman Islands, which probably once supported their own resident population. SURF RIDERS It's important to note that a crocodile on the high seas is at a disadvantage against a shark, being a far less efficient or energetic swimmer – not to mention that the reptile's ambush-style hunting tactics wouldn't be of much use in this setting. Like their Indo-Pacific counterparts, American crocs sometimes meander well outside their established range. South Florida crocs have materialized well north up the coasts of the Sunshine State, and even off South Carolina. Crocs from the Lower Florida Keys occasionally make deepwater crossings out to the remote Dry Tortugas. In Sonora, Mexico (where they've vanished), American crocs used to periodically stray northward along the Sea of Cortez's desert shores as far as Tiburon Island.

Crocodilians eating sharks, and vice versa, happens all the time, but a considerable size difference between the two is the norm. A huge shark and crocodile gnashing it out? Probably a super-rare occurrence – except, of course, in the fevered imaginations of human beings. "Predators generally don't mess with each other because the risk of a serious injury usually isn't worth it," notes Britton. "But there are always exceptions."American crocs also have an extensive, mostly coastal dominion, cruising tidewater rivers, lagoons, mangrove swamps, and offshore cays and atolls from South Florida down to South America's northern Pacific and Atlantic coasts. They've been found encrusted with barnacles, and spotted munching sea turtles at nesting beaches and pelicans offshore. In fact, one study revealed that South Florida crocodiles have a diet of 65 percent marine prey – and suggested the animals "may be capable of being ecologically isolated from freshwater ecosystems".