Which sea creature has an eye the size of a basketball?

Which sea creature has an eye the size of a basketball? The giant squid has one of the largest eyes in the animal kingdom, reaching about 10 inches (25 centimeters) across—roughly basketball-sized.

These enormous eyes are an adaptation to life in the deep ocean, where sunlight barely penetrates. A larger eye can collect more light, helping the squid detect faint bioluminescent flashes and the silhouettes of large animals. Researchers have suggested that giant squid may use this ability to spot approaching sperm whales, their major predators.

The giant squid’s eyes sit on either side of its head and contain a hard, adjustable lens. Unlike a human eye, which focuses mainly by changing the lens’s shape, the squid focuses by moving the lens, more like a camera. This design helps it see in extreme low-light conditions.

A common mix-up is the colossal squid, another enormous deep-sea cephalopod. It may also have very large eyes, but the giant squid is the standard answer to this widely cited trivia fact. Giant squid can reach roughly 43 feet (13 meters) in confirmed total length, although older estimates were often exaggerated.