To about 15 ft (4.6 m).
- Eyes large, directed upward
- Head with deep grooves on top forming "helmet"
- Caudal fin sickle-shaped, upper lobe extremely long (about 50 percent of total body length)
- Color dark purplish-brown or grayish-brown with dark metallic hues above; lighter coloring below, not extending above pectoral fins
- First dorsal fin originating well behind free tips of pectoral fins
New York to Cuba, including Gulf of Mexico.
Offshore at edge of continental shelf from surface to 1,640 ft (500 m).
Thresher shark has moderate-sized eyes directed laterally, white on abdomen extending above pectoral fins; lacks grooves on top of head.
Text descriptions taken from:
Guide to Sharks, Tunas, & Billfishes
of the U.S. Atlantic and Gulf of Mexico