They also measured the bites of small sharks such as sand sharks, and tested larger sharks by knocking them out and using electricity to stimulate the jaw muscles.

他们对诸如沙鲨等小一点的鲨鱼所咬食的伤口进行了测量，或把大鲨鱼击昏，用电击刺激其颌部肌肉，以测量其咬劲。

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Stingrays often rest on the seafloor, sometimes partially buried in the sand and color-camouflaged from predators like sharks.

刺鳐经常会在海床上待着不动，有时候身体的一部分还会埋在沙子里，同时依靠身体的色彩伪装来躲避鲨鱼等掠食者的捕猎。

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This means he can now tell legally caught Brazilian sand tiger sharks from those protected in American waters, and can catch fibbing fishermen.

ECONOMIST: DNA tracking