Pelagic Thresher - Alopias pelagicus
Like all threshers, this subspecies is a Lamniformes. The Pelagic Thresher is found in the tropical and subtropical waters of the Indian and Pacific Oceans. They’re commonly in deeper waters but occasionally enter coastal habitats. It is distinguished from the common thresher by its dark (not white) color over the bases of its pectoral fins. It’s the smallest of the three species and typically measures up to 10 feet long. Its prey usually consists of small midwater fish.
Bigeye Thresher - Alopias superciliosus
The Bigeye Thresher is found within temperate and tropical oceans worldwide. They are distinguished by their large eyes, adapted for hunting in low light conditions. Therefore, they usually stay in deeper darker waters during the day and go up to the surface at night. This shark can also be distinguished by a pair of deep grooves at the top of its head. Females can grow to up to 12 feet long. This species commonly feeds on fish, such as schooling forage fish, and squid.
Common Thresher - Alopias vulpinus
The Common Thresher is also known as the Atlantic Thresher. It is distributed worldwide in tropical and temperate oceans. This shark has a streamlined body, short pointed snout, and modestly sized eyes. It can be distinguished by the white on its belly extending in a band over the bases of its pectoral fins. This is the largest species of Thresher sharks, sometimes reaching up to 20 ft long. This sharks feeds mainly on small schooling forage fish such as herrings and anchovies.
All information comes from Wikipedia. Images are not mine.