Elephants have almost no predators and they feed on plants, so they don’t need to hear all that well (neither to protect themselves or to find food). But why do they have such big ears?
Answer
They’re for regulating the body temperature. Since an elephant has a large body mass compared to its skin surface, it needs the extra skin surface provided by the ears to regulate its internal heat (elephants are warm-blooded animals). The ears are, in fact, radiators.