Sleek Sixgill Shark Spotted...Again!
Within two days, ROV Hercules encountered two bluntnose sixgill sharks while exploring Channel Islands National Marine Sanctuary. This second shark was spotted off Santa Cruz Island at 306m (1,000ft) depth, and appears to be smaller in size than the first shark spotted. The green scaling lasers seen in this video are set at exactly 10 cm apart.
As its name suggests, this shark has a characteristically blunt rounded snout and six gill slits on either side of its head, instead of the usual five seen in most shark species. One of the larger sharks in the Eastern Pacific, bluntnose sixgills can stretch over 16ft long, bluntnose to tail! Resting along the seafloor at depths of up to 2,000m during the day, these sharks cruise closer to the surface to feed at night. Like many deep sea sharks, they tend to move slowly to conserve energy, but can reach higher speeds when chasing prey, like other sharks, rays, fish, squid, crabs, and seals--but they also have been known to scavenge.
The Channel Islands National Marine Sanctuary (CINMS) is one of the agencies tasked with the protection of deep-water habitats, commercially important species, and deep sea coral ecosystems around the islands, yet lacks a detailed understanding of the distribution, abundance, and condition of the resources within the Sanctuary. Less than 50% of the seafloor within the CINMS boundaries has been mapped by high-resolution sonar, and the 2016 Nautilus expedition to the same region worked to cut this knowledge gap nearly in half.