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Birds’ Eye Design - Bar-headed goose — Bar-headed goose (Anser indicus)

A group of biologists has finally solved one of the great mysteries of biology. For decades, scientists have wondered how birds can have keen eyesight without blood vessels to supply oxygen to the retina. Blood vessels provide vital oxygen to the retinas of other animals, but the birds’ eye design is different.

Without blood vessels that scatter the light reaching the retina, the birds’ eye design enables sharper vision. How can the retinal cells function without dying from lack of oxygen? The answer, according to researchers at Aarhus University in Denmark, is anaerobic glycolysis. “Anaerobic” means without oxygen, and “glycolysis” refers to the process of breaking down the sugar glucose. Anaerobic glycolysis is less efficient than oxygen-based metabolism, and birds’ eyes need a lot of energy. How can they get enough energy with this less-effective method?

The birds’ eye design features a unique structure that no other species has. A comb-like network of blood vessels called the pecten oculi protrudes from where the optic nerve enters the eye and moves freely within the vitreous humor, the fluid filling the eyeball. The pecten oculi transports glucose into the vitreous humor while removing carbon dioxide and lactic acid that could harm the retina.

This discovery explains how birds like bar-headed geese can fly at elevations over 6000 meters, where oxygen is scarce. The DNA of these birds is coded to overcome specific environmental challenges while maintaining sharp vision. Encoding requires an intelligent programmer who understands what birds need to survive. Bird’s eye design, like every scientific discovery, gives us a window into the creation of life on planet Earth.

Reference: “Briefings” in American Scientist for March/April 2026, page 77.

Much has been made of bacteria that live in extreme conditions. We have mentioned the forms that live in the geyser pools at Yellowstone National Park. Those bacteria use a chemical source to allow them to exist in high-temperature environments. They, in turn, provide the basis for other forms of life that use the Sun as their energy source. The British Broadcasting Corporation has had numerous features in which they have reported on other animals that function in extreme environments. Some of the examples that the BBC cites are:

The sperm whale feeds 2000 meters down in the ocean where the pressure “is the equivalent of carrying ten jumbo jets on your back.” The whales deflate their lungs to do this and then spend up to an hour using chemically-stored oxygen to supply their muscles while they are down there.

Polar bears spend seven months without eating or drinking and then give birth in an area where the temperatures can hit -60 Celsius and the winds can reach 160 km/hr.

The bar-headed geese that fly over the Himalayas at 10,000 feet by concentrating oxygen with their special lung design.

We have discussed some of these mechanisms in the past. Their design and construction are not well explained by chance hypothesis proposals. It would seem that a designer was involved in these intricate systems. God wanted all the earth to be inhabited, but to do that a variety of very specialized structures had to be built into living things. Romans 1:18-22 tells us that we can know there is a God by seeing this design in living things. Extreme animals, just like extreme bacteria, powerfully testify to the truth of that message.
–John N. Clayton © 2017

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Birds’ Eye Design

Extreme Animals