Here's why:
* Body size: While body size is a factor, it's not the only one. Some large mammals have proportionally larger eyes than others.
* Habitat and Lifestyle: Eye size is also influenced by habitat and lifestyle.
* Nocturnal animals: Animals that are active at night often have larger eyes to gather more light in low-light conditions.
* Aquatic animals: Whales and dolphins have relatively small eyes compared to their body size, as vision underwater is less important than echolocation.
* Predators: Predators often have larger eyes for better vision and hunting.
* Specific adaptations: Some mammals have developed unique eye adaptations. For example, elephants have relatively small eyes, but their wide-set eyes allow them to have a panoramic view of their surroundings.
Examples:
* Humans have relatively large eyes compared to our body size.
* Whales have small eyes compared to their massive size, as they rely more on echolocation.
* Hippos have relatively small eyes compared to their body size.
* Elephants have small eyes, but their wide-set placement allows them to have a broad field of vision.
* Cats have large eyes that are adapted for night vision.
Therefore, it's inaccurate to generalize that all large mammals have roughly the same size eyes. Eye size is influenced by various factors, making it a diverse characteristic across different species.