Giant mako shark interrupts film session, gives diver scare of a lifetimeJim Abernethy was enjoying a peaceful dive while filming a hooked marlin when he got an unwelcome visitor.Jim Abernethy was enjoying a pleasant dive in the calm, clear waters of the Bahamas recently, filming a hooked blue marlin, when a giant mako shark buzzed over his right shoulder and sped into the camera's view. Abernethy's startled reaction, at the 30-second mark, is understandable given that the shark could have struck him entirely without warning.The episode played out during a Guy Harvey expedition at Cat Island. Harvey, a renowned marine artist who uploaded the video on Wednesday, described the mako as a 10-footer weighing 600 pounds.The shark may have been drawn into the area by the struggling marlin.Abernethy, who runs Jim Abernethy's Scuba Adventures in Florida, is considered a shark expert and he's accustomed to diving with the predators. But even a shark expert cannot be expected to remain calm when surprised from behind, at such close range, by so large a specimen.Mako sharks, which are found in tropical and sub-tropical waters around the world, can exceed 1,000 pounds. They're the fastest of shark species, capable of swimming at speeds up to 20 mph, and have been implicated in sporadic fatal and non-fatal attacks on humans