Box jellyfish possess 24 sophisticated eyes, including lenses, retinas, and corneas remarkably similar to human eyes.

Box jellyfish, specifically species like Tripedalia cystophora, possess one of the most unique visual systems in the animal kingdom. Their 24 eyes are organized into four sensory structures called rhopalia, located on the sides of their bell. Each rhopalium contains six eyes: four simple light-detecting pits and two complex 'camera-type' eyes equipped with a lens, retina, and cornea. These camera eyes are structurally similar to those of vertebrates, though they are evolved independently.Research published in journals like Current Biology highlights that these jellyfish use their vision for complex navigation. For instance, they can identify the dark silhouettes of mangrove roots to avoid collisions or find food. This is particularly impressive because jellyfish belong to the phylum Cnidaria and lack a centralized brain. Instead, they rely on a decentralized nerve net and a ring of neurons to integrate visual signals and trigger motor responses.Studies by marine biologists such as Dan-Eric Nilsson have shown that while their lenses are high-quality, the retinas are positioned slightly out of focus. This creates a natural low-pass filter that helps the jellyfish ignore tiny particles in the water and focus on large objects. This specialized vision allows them to swim at speeds of up to 4 knots while actively pursuing small fish and crustaceans. Their ability to process color and spatial orientation without a brain remains a major subject of neurobiological study.