> Which animal has the largest eyeball in the world?And the answer: the giant squid.The giant squid has the largest eyeball in the animal kingdom. More than 25centimeters in diameter, the squid's eyeball is about the size of a dinnerplate, or as big as a human head. Scientists believe the large eyes help thesquid recognize large shapes of predators moving in the water, like the spermwhale.Photo credit: TSUNEMI KUBODERA OF THE NATIONAL SCIENCE MUSEUM OF JAPAN/AP.If youthought whales were the only massive creatures inhabiting the depths of ourseas, you might have to strap in for this one. The aptly named giant squid isthe largest invertebrate on Earth, though, curiously, the most elusive. Thesesea creatures dwell exclusively in the deepest parts of the ocean, making itincredibly difficult for researchers to learn more about their species orobserve them in their natural habitats. In fact, most of what we know of thesesquid comes from those that have washed ashore or been accidentally hauled in byfishermen. That is, until 2004, when researchers in Japan took the first ever photos of thegiant squid. And, in 2006, scientists with Japan's National Science Museummanaged to surface a 24-foot female giant squid (though that might seemfrighteningly big, the largest of these giants ever to be measured clocked in ata staggering 59 feet long). Giant squid have some of the most unique qualities of any animal on the planet,land or sea. Their massive eyes allow them to seek light and make sense of theirsurroundings in the lightless depths of the ocean, with water-filled retinasthat deflate in air. Meanwhile, their diet consists of anything from shrimp to,it's believed, small whales (yes, you read that right). Giant squid are alsoequipped with long tentacles that are twice their body length, allowing theirgrip to shoot out far and wide to catch prey. Scared yet? Us too. Learn more about giant squid here[https://ocean.si.edu/ocean-life/invertebrates/giant-squid].