Summary in Seconds:
What if you discovered a toad with its eyes inside its mouth? As bizarre as it sounds, such an animal was found in Canada in 1992, and its remarkable photograph became famous around the world. Far from being a hoax, this rare developmental abnormality offers scientists a fascinating glimpse into how embryos build complex organs. By exploring how cells communicate during early development—and how rare mutations, parasites, pollution, or other environmental factors can disrupt that process—this extraordinary toad reveals not only the delicate precision required to create a healthy animal, but also how studying nature’s rare mistakes helps scientists better understand birth defects, regenerative medicine, and the fundamental processes that shape all living organisms.
Nature never ceases to surprise us. Our planet is home to countless unusual animals, from bright pink river dolphins [1] and “lipstick-wearing” fish [2] to tiny creatures that seem to have stepped out of a fantasy novel. While many of these remarkable animals evolved to look unusual, others owe their appearance to rare developmental abnormalities that occur before they are even born.
Among the most astonishing examples is a toad whose eyes developed inside its mouth.
At first glance, the story sounds like an internet hoax. Yet it is completely true, and for more than three decades it has fascinated both scientists and the public alike.
The story began in 1992, when Scott Gardner [3], a newspaper photographer for The Hamilton Spectator [4] in Canada, received an unusual phone call. A family in Burlington, Ontario, claimed they had discovered a toad in their backyard with its eyes inside its mouth. Gardner initially assumed someone was playing a practical joke, but curiosity persuaded him to investigate.
To his amazement, the family had described the animal perfectly.
The toad had no visible eye sockets [5]. Instead, both of its eyes were embedded in the roof of its mouth.
Gardner photographed the extraordinary animal, and the image quickly spread across Canada and the United States. It later appeared in scientific publications and popular science books, including Richard Dawkins’ Climbing Mount Improbable [6]. Even today, the photograph continues to circulate on social media, with many people wondering whether it has been digitally manipulated. It has not. The photograph is genuine.
Although many people refer to the animal as a frog, it was actually an American toad (Anaxyrus americanus, formerly Bufo americanus). Frogs and toads [7] belong to the same biological order, Anura. Toads generally have rougher skin, shorter legs, and spend more time on land, whereas frogs typically have smoother skin, longer legs, and are more closely associated with water. In other words, every toad is technically a frog, but not every frog is a toad.
The unusual anatomy left scientists with an obvious question: How could an animal develop perfectly functional eyes inside its mouth?
The answer lies in one of the most fascinating fields of biology—embryonic development [8].
As an embryo grows, its organs do not simply appear in predetermined locations because of a fixed genetic blueprint. Instead, developing cells constantly communicate with one another through molecular signals [9]. These chemical messages tell neighboring cells what they should become, when they should develop, and precisely where they should form. This remarkable process, known as embryonic induction [10], allows billions of cells to work together to build a complex living organism.
The development of the eye provides one of the classic examples of this process.
Early in embryonic development, a small outgrowth from the developing brain forms a structure called the optic vesicle [11], which later develops into the retina [12]. While the mature retina eventually detects light, its embryonic role is equally important. It releases molecular signals that instruct the overlying surface tissue—the ectoderm [13]—to develop into the lens of the eye [14]. Without these signals, the lens simply never forms.
In other words, the developing retina directs neighboring tissues to construct the rest of the eye.
Developmental biologists demonstrated this principle through a series of elegant experiments. When they transplanted a developing retina to an unusual location in a frog embryo—for example, near the future mouth—the retina continued sending the same chemical instructions. Nearby cells responded exactly as they normally would, producing a lens and other eye structures in that entirely abnormal location.
These experiments revealed an important truth: genes alone do not determine where organs develop. Continuous communication between neighboring tissues is equally essential.
The remarkable toad photographed by Gardner appears to be a naturally occurring example of this process gone dramatically wrong. Instead of forming in their normal position, the eyes developed within the roof of the mouth.
Macromutations: Rare Developmental Events
Researchers believe this rare condition probably resulted from a major developmental mutation—sometimes called a macromutations [15]—that produces large structural changes rather than the small genetic variations [16] commonly found within populations. Such mutations are exceptionally uncommon, but they occasionally occur in amphibians.
Exactly what triggers these abnormalities remains uncertain.
In Part Two of this two-part article, I will define macromutations and explain their possible causes and consequences.
Notes
1. Pink River Dolphin (Pink River Dolphin)
The pink river dolphin is a rare species of freshwater dolphin that inhabits the Amazon and Orinoco river basins in South America. It is distinguished by its pink coloration, which often becomes more pronounced with age, and is thought to result from a combination of natural pigmentation and the rich network of blood vessels beneath its skin.
2. Red-Lipped Fish
The term red-lipped fish refers to certain fish species that possess bright red lips, such as the red-lipped batfish. The vivid coloration is believed to aid in communication between individuals or in attracting mates, giving these fish the appearance of wearing lipstick.
3. Scott Gardner
Scott Gardner is a Canadian photographer known for documenting wildlife and unusual natural phenomena. He gained widespread recognition after photographing an American toad whose eyes appeared inside its mouth—a remarkable image that astonished scientists and led to the documentation of an exceptionally rare congenital abnormality.
4. The Hamilton Spectator
The Hamilton Spectator is a Canadian daily newspaper published in Hamilton, Ontario, and is one of Canada’s oldest newspapers. It covers local, national, and international news and published reports about the extraordinary toad photograph that attracted the attention of the scientific community.
5. Eye Sockets (Orbits)
The eye sockets, or orbits, are the bony cavities of the skull that house and protect the eyes. They also contain the muscles, nerves, and blood vessels necessary for normal eye movement and function.
6. Richard Dawkins’ Climbing Mount Improbable
Climbing Mount Improbable is a book written by evolutionary biologist Richard Dawkins in 1996 to explain how evolution can produce complex biological structures through the gradual accumulation of small changes. Using the metaphor of climbing a mountain by a gentle slope rather than scaling a sheer cliff, Dawkins illustrates how seemingly impossible adaptations can arise through millions of years of natural selection.
7. Frogs and Toads
Frogs and toads are two groups of amphibians belonging to the order Anura. Although they share many fundamental characteristics, frogs typically have smooth, moist skin, whereas toads generally possess rougher, drier skin and a more robust body.
8. Embryonic Development
Embryonic development is the series of stages through which an organism progresses from the fertilization of the egg until its organs and tissues are fully formed. During this process, cells divide, differentiate, and organize themselves with remarkable precision to create the complete body.
9. Molecular Signals
Molecular signals are chemical substances or proteins that cells use to communicate with one another during development and throughout normal physiological processes. These signals determine when cells divide, where they migrate, and what type of tissue they ultimately become.
10. Embryonic Induction
Embryonic induction is the process by which one tissue or group of cells influences neighboring cells, directing them to develop into a specific tissue or organ. This process is essential for ensuring that organs form in the correct locations during embryonic development.
11. Optic Vesicle
The optic vesicle is an early embryonic structure that emerges from the developing brain and represents the first stage in eye formation. It sends molecular signals to neighboring tissues, stimulating the development of the lens and other components of the eye.
12. Retina
The retina is the light-sensitive layer located at the back of the eye. It contains rod and cone photoreceptor cells that convert light into nerve impulses, which are transmitted through the optic nerve to the brain to produce vision.
13. Ectoderm
The ectoderm is one of the three primary germ layers formed during the earliest stages of embryonic development. It gives rise to the nervous system, the skin, hair, nails, the lens of the eye, and several other structures.
14. Lens of the Eye
The lens is a transparent structure located behind the iris that focuses incoming light onto the retina to produce clear vision. It continually changes shape to focus on objects at different distances through a process known as accommodation.
15. Major Mutation
A major mutation is a large-scale genetic change that affects a significant portion of the genome or a critical developmental gene, potentially producing substantial alterations in an organism’s structure or function. Most such mutations are harmful or lethal, although a small number may survive and occasionally give rise to new traits.
16. Small Genetic Variations
Small genetic variations are minor differences in DNA among individuals, usually arising from small mutations or the reshuffling of genes during reproduction. These variations provide the raw material for evolution, allowing natural selection to favor those that improve an organism’s survival or reproductive success.
References
1. The Travel Staff. “A photographer in Canada found a toad with eyes in its mouth, and scientists were baffled.” The Travel, June, 24, 2026.
https://www.thetravel.com/photo-of-toad-with-eyes-in-mouth-found-in-canada
2. Developmental Biology. (2020). Developmental Biology (12th ed.). Sinauer Associates / Oxford University Press.
3. Principles of Development. (2019). Principles of Development (6th ed.). Oxford University Press.
4. John Gerhart, J., & Marc Kirschner, M. (1997). Cells, Embryos, and Evolution. Blackwell Science.
5.. Langman’s Medical Embryology. (2024). Langman’s Medical Embryology (15th ed.). Wolters Kluwer.