Scientists in awe as prehistoric-looking shark appears on deep-water video feed

Sixgill shark probes ocean floor at a depth of 700 feet.

Scientists studying the depths around California's Channel Islands on Monday were surprised to see a prehistoric-looking sixgill shark appear in the video feed.

A camera-fitted ROV, operated by the crew of the E/V Nautilus, was exploring a chasm nearly 700 feet deep at Santa Cruz Island when the large shark was spotted on the fringe of the ROV's lights.

"That could be a sixgill shark," one of the crew says in the minute-long clip, posted to Twitter on Tuesday.

Moments later the robust shark is fully in view, prompting a scientist to marvel, "Wow… check this out," as the shark swims sluggishly through the artificial light.

The crew did not offer a measurement, but the shark appears to be at least 10 feet long.

Bluntnose sixgill sharks, which typically measure to about 16 feet, are mysterious because they spend so much time at great depths (600 to 3,000 feet) and are rarely encountered.

The sharks, which possess six gill slits on each side (versus five on most other shark species), resemble fossil shark types that date back 200 million years, to the Triassic period of the Mesozoic Era.

Sixgill sharks, which reside in tropical and temperate seas, have only a single dorsal fin and a long tail. Their small eyes are bright green. Their prey includes seals, fish, rays, squid, and other sharks.

Though sixgill sharks rarely exceed 16 feet in length, much larger specimens have been documented.

Earlier this year a sixgill measuring 25 feet and weighing 1,500 pounds was reeled from the depths by an angler off Ireland.

The E/V Nautilus is conducting a yearlong study of the Eastern Pacific, from Canada to Mexico's Revillagigedo Islands.

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