Paddlefish Have a Third Eye

Paddlefish Have a Third Eye

North American waters are home to a most interesting fish known as the spoonbill or paddlefish (Polydon spathula). These fish have an enormous bill, which is actually an antenna studded with thousands of sensory cells to detect electrical signals produced by the plankton on which they feed. The 12—to 15-inch long bill gets so much attention that people overlook another oddity: these paddlefish have a third eye.

Paddlefish have an opening between the bones of the skull called a foramen. It is located at the base of the bill between the eyes and covered by a thin skin and cartilage layer. The foramen allows light to pass through onto a nerve that goes directly to the paddlefish’s brain. It serves as a third eye, allowing the paddlefish to experience changes in light direction and seasonal changes. The third eye cannot form detailed images, but it influences biological changes in body temperature and hormone production in the fish.

As biologists study various life forms, they find common threads that run through all living things. Researchers have found barely visible vestiges of similar structures in frogs, lizards, and some sharks. Since paddlefish have a third eye, they must have a use for it, but the last detailed study of it was in 1896.

There are many things that science does not yet know about living things, but diverse features allow animals to live in Earth’s wide-ranging environments. Evolutionists assume that all life originated from a single cell in the distant past through an unguided chance process. The paddlefish bill with its sensory cells and third eye is difficult to explain by that process. God used the best plan in creating life, and part of that is the capacity to change as the environment changes. Romans 1:20 tells us that “we can know there is a God through the things He has made.”

— John N. Clayton © 2024

Reference: “Third Eye of a Spoonbill” in In-Fisherman magazine for May 2024, pages 8-9.

Electroreceptors of Paddlefish

Electroreceptors of Paddlefish

The American paddlefish is an interesting but relatively unknown fish species. These fish have large paddle-shaped appendages on their foreheads, and they inhabit the murky waters of the Mississippi River and its tributaries. They can grow to six feet (183 cm) and weigh 150 pounds (68 kg). So what is the purpose of the paddle? The electroreceptors of paddlefish answer that question.

You might think that the paddle is a device to dislodge food from river bottoms. Some people called them “shovelnose fish,” assuming they used their paddles as a shovel. But paddlefish don’t dig for food, and lab experiments in 1993 showed the paddle’s real purpose.

Paddlefish are filter feeders that feed on tiny crustaceans and insect larvae that drift through the water as plankton. Many whale species are filter feeders that use comb-like baleen in their mouths to strain their food from the water. Paddlefish have comb-like rakers in their gills. They swim with their mouths open and filter their food from the water. But that doesn’t explain the paddle.

Paddlefish have poor eyesight and no sense of smell, so how do they know where to swim to find food? The paddle is covered with tens of thousands of electroreceptors that can sense extremely minute electric fields. Plankton emit signals that are similar to what doctors measure in electrocardiograms. Paddlefish use their electroreceptors to detect those signals and locate the plankton, even in murky waters.

The electroreceptors of paddlefish are similar to those of the platypus found in Australia. Many marine fish, including sharks, skates, rays, and some freshwater fish, can use weak electrical signals for feeding and communication. Those fish don’t need light or clear water to eat and maintain a balance in the environment. This ability is not something that evolved in the paddlefish because fossil evidence seems to indicate that they had electrosense ability very early in Earth’s history. We are amazed by God’s designs that we see in living things.

— John N. Clayton © 2020