Sixgill Shark Identification Guide

Key identification features

• Six pairs of gill slits, one more than nearly all other shark species, which have five
• Single small dorsal fin positioned very far back on the body, near the pelvic fins
• Broad, blunt head with large green or amber eyes adapted to low light
• Long, tan to olive-brown or grayish body that can exceed 15 feet in large adults
• Elongated lower lobe of the caudal fin, much longer than the upper lobe

Common look-alikes

• Sevengill shark: has seven gill slits instead of six and typically shows dark spots scattered across the body
• Bigeye sixgill shark: also has six gills but is smaller overall, has proportionally larger eyes, and favors warmer, tropical waters
• Frilled shark: has six or seven gill slits with frilled edges and a much more eel-like, elongated body shape

Where you'll see one

Sixgill Sharks are deepwater sharks found on continental shelves and slopes worldwide, typically at depths of several hundred to over a thousand feet, though they migrate into shallower water at night to feed.

Counting the gill slits is the single most decisive step in the field; once six are confirmed alongside the far-back dorsal fin, few other large sharks remain as possibilities.