Adam Clarke on Job 18:13

It shall devour the strength of his skin - This may refer to the elephant, or to the rhinoceros, whose skin scarcely any dart can pierce: but in the case referred to above, the animal is taken in a pitfall, and then the first-born of death - a sudden and overwhelming stroke - deprives him of life. See the account of hunting the elephant in the East at the end of the chapter, Job 18:21 (note). The Chaldee has: "The strength of his skin shall devour his flesh; and the angel of death shall consume his children."