Four-Eyed Fish – Anableps

Throughout the natural world, we see special design features that allow animals to survive in environments that place unique demands. Chameleons have an eye-brain connection that enables the eyes to rotate independently of one another or work together when needed. Chameleons use their tongues to catch insects, but to capture their food, both eyes must work together to overcome depth perception issues. At the same time, chameleons are very vulnerable to predators, so their eyes must rotate independently to look in several directions at once. We find another example of unusual eyes in the genus of four-eyed fish, Anableps.

Anableps live in northern South America and Trinidad, where they swim in the surface waters of lakes and rivers. Near the surface, they are easy prey for birds, so they need to see above and below the water simultaneously. They appear to have four eyes, two above the water surface, and two below the surface. In reality, they are not separate eyes. The eyes are divided into two sections, separated by a band of tissue.

Each section of the Anableps eyes has two corneas, two pupils, a single egg-shaped lens, and one retina that is also divided. The portion of the eyes located above the water connects to a different section of the fish’s brain than the area below the waterline. These four-eyed fish are ideally suited to fill an ecological niche that no other fish can.

You might think that all fish could use this design, but every ecological niche has animals designed to inhabit and maintain that location. Anableps are unique, and that makes them popular aquarium fish. More importantly, this unique design speaks of God’s imaginative creativity in providing full use of every resource on planet Earth with creatures like the four-eyed fish, Anableps.

— John N. Clayton © 2020