There are currently 3 species of thresher shark: common, pelagic, and bigeye thresher shark.
Their unique quality is their unusually long tail. The tail is typically larger than their whole body, and is used to stun prey. I imagine getting hit with that tail would sting!
To counter the tail, their bodies are slim and they feature very small mouths.
long pointed nose, big eye (hence name)
longest thinnest tail, straight nose
largest in size, rounded and short nose snout