Bluntnose sixgill sharks are one of the oldest species of sharks and are thought to have a prehistoric lineage as they closely resemble fossil forms dating from the Triassic period, which was approximately 200 million years ago.  The species can grow up to 18 feet long and has a powerful body with a broad head and small florescent green-blue eyes.  The rounded snout is blunt and there are six long gill slits on each side of the head, hence the name "bluntnose sixgill shark," which is distinguishable from the more typical five gill slits found in other shark species.  

The bluntnose sixgill shark is one of the wider ranging sharks, residing in temperate and tropical seas around the world.  This shark is primarily a deepwater species living along outer continental and insular shelves as well as upper slopes of the world's oceans.  It rests along the bottom during the day at depths recorded as deep as 6,152 feet, swimming close to the surface or moving into shallow waters at night to feed.  Due to its prevalence in deepwater habitat, casual sightings of the bluntnose sixgill shark can be rare and studying them can prove to be difficult.  The exception to this is in the Puget Sound where the unique combination of water depth and habitat provides a rich environment for this species.  Studies over the past 20 years support the notion that some female bluntnose sixgill sharks return to the Puget Sound to give birth in relatively shallow waters, where their offspring spend their formative years in productive estuaries.  Scientific interest in the sixgill sharks of Puget Sound piqued in the late 1990s when recreational divers began encountering a surprising number of these sharks.  In 2003 the Seattle Aquarium began studying the bluntnose sixgill shark in partnership with the National Oceanic and Atmospheric Administration and the Washington Department of Fish and Wildlife (WDFW).  The number of sixgill sharks in the Puget Sound reached a peak between 1999 and 2007, after which the number of sharks suddenly declined with no confirmed explanation.  The WDFW classifies the sixgill shark as a “species of greatest conservation need” in the State Wildlife Action Plan which is a comprehensive plan for conserving the state's fish and wildlife and the natural habitats on which they depend.  Directed fishing for bluntnose sixgill sharks is not allowed under state fishing regulations and any that are caught accidentally must be released without removing them from the water.

In the last several years, recreational divers have reported a slight increase in the number of bluntnose sixgill sharks spotted in the central Puget Sound waters near Federal Way and Des Moines.  The City of Des Moines recently officially declared itself the Sixgill Shark Capital of the World and designated July 6 as Sixgill Shark Day. 

Designates the hexanchus griseus, also known as the bluntnose sixgill shark, as the official shark of Washington.