Animals have different ear shapes because the ears of each animal group are adapted for their specific environment and needs. For example, predators have ears that face forward to allow them to focus on their prey. Prey animals often have ears that can be moved around. This allows them to listen in every direction for threats.
The primary purpose of the outer ear is to gather sound waves for hearing. The shape of the outer ear reflects this. Nocturnal animals and animals that live in dim habitats have larger outer ears because they rely more on sound than animals who are awake during the day and use more visual cues. Sea animals and birds do not have outer ears because they would make too much noise from drag when the animal swims or flies.
Ear shapes also reflect other adaptations. Elephants, fennec foxes and many desert animals have large ears to help them stay cool. Blood travels through the animals' ears and releases heat into the air. Bats use hearing to find their way around and catch prey by bouncing sound waves off objects in their environment. They are able to change the shape of their ears quickly and accurately to aid in this process.