BOCA GRANDE — For decades, legendary hammerhead Old Hitler has been the subject of fishing folklore up and down the southern coast of the Gulf of Mexico.

Depending on the source, Old Hitler has a head as wide as a pickup truck, and is longer than most of the fishing boats it's been spotted from.

The hammerhead is big enough to swallow other sharks in a single bite, and strong enough to drag a Jeep from the shoreline by its bumper-mounted winch.

His massive body is covered in scars from encounters with fishermen's machetes, harpoons and boat propellers.

Even though the legend has evolved over the last century, what always remains constant — Old Hitler is the biggest, meanest shark to ever roam the waters from Everglades City to Tampa Bay.

The mighty shark has been the subject of numerous newspaper headlines and documentaries over the years. It has been immortalized in art and song. Stories of close encounters have been told around bait buckets for generations, passed down from father to son like heroic war stories.

The fabled fish even got its own prime-time slot in this year's Shark Week marathon on the Discovery Channel, which has spent 27 years celebrating the ocean's apex predators.

Although tales of massive hammerheads have been common up and down the coast since the turn of the 20th century, it wasn't until World War II that those tales took on near-mythical proportions.

As the war efforts ramped up, German U-boats invaded American water, waging an all-out assault on any and all marine vessels. In 1942 alone, the German submarines recorded 56 attacks on American ships off the coast of Florida, 40 of which ended up on the ocean's floor. Among them was the Baja California, a freighter carrying a load of military transport vehicles. The freighter was torpedoed and sank 55 miles off the coast of Marco Island.

To combat the invasion, the United States Coast Guard and Navy deployed dirigible blimps to patrol the coast. Merchant mariners and supply vessels, paranoid from the attacks, reported sightings of unidentified watercraft cruising around the major shipping ports. Many of those sightings were attributed to giant hammerhead sharks cruising along the surface.

As commercial fishing became one of the major local industries after the war, encounters with great hammerheads became more and more frequent. Anyone who spent time on the water seemed to have a hammerhead story, and they were just believable enough to be true.

When Tampa Bay became the dominant shipping port in Florida, the shark's legend followed north where it became bigger than ever.

Tales of a 20-foot hammerhead circulated. The supposed shark was as dark as a shadow and covered in scars. There was a notch in its dorsal fin, a result of a run-in with a commercial mullet fisherman off the coast of Useppa Island in the early 1960s. The fisherman struck the shark with a machete after it mauled a net full of fish and began bumping the 15-foot vessel. The shark swam away with the large knife still embedded in its dorsal fin.

There was a swastika-shaped scar on its forehead, a result of either a propeller scar or the carvings of some wayward local youth, depending on the source. It was just one of many battle scars that covered its dark brown skin.

Like many a great folk tales, this fantastic fish story is rooted in fact.

The great hammerhead is the biggest of the hammerhead species — with its flattened mallet-shaped head — found locally. They routinely grow to mammoth proportions, reaching 20 feet in length and can easily weigh more than 1,000 pounds.

"It's amazing that these animals have been able to survive through several mass extinction events with little change to their biology," said Dr. Matt Ajemian, marine biologist and member of the Shark Week expedition.

"They've got such a unique morphology with the hammer, and they are one of the biggest sharks in terms of ones that humans come in contact with, especially near the shore where encounters are prevalent," said Dr. Greg Stunz, director of the Harte Research Institute and also part of the Shark Week expedition.

Hammerheads are frequent visitors along the Gulf Coast, arriving en masse as they follow the schools of tarpon heading north. Once the water begins to cool in late fall, the hammerheads head south again.

For as long as fishermen have set their lines in the Gulf, encounters with those massive hammerheads have been common.

In 1905, while turtle fishing off the coast of the Everglades aboard his boat The Barracouta, Capt. Charlie Thompson hauled in a 20-foot hammerhead that weighed in at 2,169 pounds.

Soon news of Florida's "man-eating monsters" circled the country. However, there were always reports of at least one shark that stood out as a king among the beasts.

"He is a shark of the most sharklike propensities and his fury when he gets entangled in a net — as he sometimes does — is of the most ferocious nature," said a Los Angeles Herald article published in February 1906.

Boca Grande Pass, the tiny body of water connecting Lee and Charlotte counties at the mouth of the Peace and Myakka rivers, soon became a world-renowned haven for sharks of epic proportions.

Boca Grande Pass remains the primary grounds for large hammerheads, with the past three International Game Fish Association world records being pulled from the area — including the current record holder, Bucky Dennis, who caught a 13-foot, 1,360-pound hammerhead in 2008.

Those same hammerheads pass through the Everglades, which provides a vital spawning ground for the species, and into Tampa Bay, especially off Egmont Key, another deep-water ledge that acts as an aggregation point for schooling tarpon.

As the legend of Old Hitler grew, so did the stories surrounding it.

Fishermen always claimed the shark was bigger than their boat, no matter how big of a vessel they had.

It became meaner and more brazen, often attacking a boat's propellers unprovoked. Many fishermen claimed to be lucky to be alive after the encounter. And even though the frequency of the sightings increased, no one ever managed to catch the beast, which only perpetuated the myth.

"It has been harpooned, shot at, and has been on any number of fishing lines," Brian Martel told Bob Bender of the then-St. Petersburg Times in a June 21, 1976, article.

In 1981, Old Hitler was featured on the World of Sports Afield television series. By that point, the shark already was a bit of a TV celebrity due to regular segments on Tampa's Fox 13 News by longtime sportscaster "Salty" Sol Fleischman. Fleischman, an avid outdoorsman, regaled audiences with tales of the giant hammerhead, and birthed many of the legend's most retold details.

The average life span of a great hammerhead is between 25 and 30 years, with some sharks believed to live up to 50. The massive shark that trailed the cargo boats that entered Boca Grande Pass around the turn of the century isn't likely to be the same fish that fueled the paranoia.

In all probability, Old Hitler was never a single shark — even from the earliest days of the legend — but instead was a series of sharks that have managed to outgrow their brethren and claim this part of the Gulf of Mexico as their own, a behavior marine biologists refer to as site fidelity. It is a succession that continues to this day.

It just so happens that the biggest, meanest hammerhead seen in local waters at any given time is given the moniker of Old Hitler. In many ways, Old Hitler is like the Gulf's own version of Loch Ness — an everyman's version of Jaws.

"There is a sense of knowing that there is something big out there. There is a mystery to the seas, and Old Hitler fits into that picture," said Scotty Lee Rexroat, frontman of the band Treble Hook, who tells the tale of Old Hitler in his song, Shark Fishing on the Skyway Pier.

"Everybody wants to catch the biggest fish out there and that is why the legend of Old Hitler has had such staying power."