American Curl kittens are born with straight ears, which begin to curl within forty-eight hours. After four months, their ears will not curl any longer, and should be hard and stiff to the touch at the base of the ear with flexible tips. A pet quality American Curl may have almost straight ears, but showcats must have ears that curl in an arc between 90 and 180 degrees. A 90 degrees is preferable, but cats will be disqualified if their ears touch the back of their skulls.