Hexanchus


The sixgill sharks are a genus, Hexanchus, of deepwater sharks in the family Hexanchidae. These sharks are characterized by a broad, pointed head, six pairs of gill slits, comb-like, yellow lower teeth, and a long tail. The largest species can grow up to 8 m long and weigh over 600 kg. They are continental shelf-dwelling and abyssal plain scavengers with a keen sense of smell and are among the first to arrive at carrion, together with hagfish and rattails. They show a characteristic rolling motion of the head when feeding.
They have been found at depths of up to. Though only two extant species were originally known, a third, the Atlantic sixgill shark, was found to exist.

Swimming Behavior

The bluntnose sixgill shark, Hexanchus griseus, is relatively common to scientists. However, very little information exists about its distribution patterns, migrations and behavior. Data on occurrence and behavior of sixgill sharks inhabiting waters north of Spain were obtained from yearly oceanographic trawl surveys.
Data obtained from one electronic pop-up tag, provided information about depth and temperature preferences over 75 days. Mean depth obtained during that period was 913 m, and the mean temperature was 10.3 °C,. Movements up and down in the water column within a single day ranged from 50 to 385 m. No cyclic diel vertical migration was however observed, the shark moved smoothly without a defined pattern.
The six-gill sharks have the ability to alter their feeding behaviors due to the situation that they are in. A feeding behavior analysis displayed that the six-gill sharks are able to utilize a bite of food compared to other aquatic vertebrates.

Extant species