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Animals With Two Heads (Polycephaly)

Nature never fails to astonish us with its remarkable diversity and extraordinary anomalies. Among these curiosities are animals with two heads, a rare phenomenon that captivates the human imagination. From two-headed snakes to conjoined twins in humans, these species have long intrigued scientists and sparked the public’s curiosity.

Delve into the lives of some of the creatures involved in this highly unusual phenomenon and uncover more about their captivating story in this article.

A two-headed calf | image by Kolossos via Wikimedia Commons | CC BY-SA 3.0

Understanding Polycephaly

Polycephaly, a term derived from the Greek words “poly” meaning “many” and “kephalē” meaning “head”, refers to a condition where a single organism possesses more than one head. Observing a polycephalic organism might present the impression of a single entity with additional heads, or multiple individuals sharing a single body. It’s a fascinating, albeit unusual, phenomenon that provides a glimpse into the complexities of biology and development.

Polycephaly in Nature

Primarily, we observe two or three-headed animals as the multi-headed creatures in the natural world. This unusual occurrence aligns with the formation of conjoined twins, originating when embryos of monozygotic twins (identical twins from a single fertilized egg) fail to separate entirely during the early stages of development.

While the occurrence of multi-headed beings is a rarity, they have indeed been documented throughout history and across various species, providing both fascination and significant insights for scientific research.

How Polycephaly Occurs

According to scientific research, two primary mechanisms can lead to polycephaly:

  1. Fission: In this process, the fertilized egg or embryo starts to split (as it would when forming identical twins), but the split is incomplete, resulting in two (or more) heads attached to a single body.
  2. Fusion: Also known as ‘Siamese’ or ‘conjoined’ twins, this occurs when two separate fertilized eggs or embryos come together and fuse in early development, forming a single organism with more than one head.

Both mechanisms result from complex and not fully understood genetic and environmental factors, with the precise cause often varying on a case-by-case basis.

Recorded Instances and Species

Instances of polycephaly have been observed and documented in various animal species. Below is a table outlining some examples:

Species Description
Snakes Two-headed snakes are often found in the wild and captivity, with each head having its own brain and being able to think and eat independently.
Turtles Two-headed turtles, like the famous Thelma and Louise at the San Antonio Zoo, can live long lives and are often seen as curiosities.
Cows & Sheep Polycephaly in these animals usually results in stillbirths, but there have been recorded instances of multi-headed calves and lambs surviving.
Humans Conjoined twins are a form of polycephaly in humans, and successful surgical separations have become more common in recent years.

Polycephaly is a rare, intriguing phenomenon offering an exceptional window into the biological mechanisms behind embryonic development and differentiation.

As science advances, our understanding of this condition will continue to grow, shedding light on the broader aspects of developmental biology and genetics. While polycephalic creatures may seem fantastical or the stuff of legends, they are, indeed, part of the extraordinary tapestry of life on Earth.

Other examples of two-headed animals in history

1. Snakes

Two-headed rat snake
Two-headed rat snake | image by Lester Snapwell via Flickr | CC BY 2.0

In the past few years, many researchers have found some two-headed snakes, and one of them is the two-headed eastern copperhead snake. John Kleopfer, who studies reptiles for the state, found it in a flower bed outside a house in Woodbridge, Virginia.

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Despite just having one stomach, the snake in question is feeding well. The two heads, though, don’t always work together because one head may be more dominant, and they may go in separate directions.

Another one is the two-headed black rat snake that Gordon Burghardt, a researcher at the University of Tennessee, encountered. These animals had two stomachs and competed head-to-head for prey. It survived for 20 years, which is remarkable.

2. Frank and Louie 

Frank and Louie were a famous Janus cat, which is another name for a cat with two different faces. Since cats with two faces often live shorter lives due to health issues related to their abnormality, the animal held the Guinness World Records record for the longest-living Janus cat. Remarkably, Frank and Louie were able to live for 15 years despite their condition.

Lyons, who specializes in feline genetics, believes that Janus cats have only one brain, even though they have two faces. However, she thinks that there might be some irregularities in brain function.

The fact that other organs, like the esophagus, weren’t duplicated likely contributed to Frank and Louie’s ability to survive and live a longer life.

3. Sheep

Two-headed lamb
Two-headed lamb | image by LaggedOnUser via Flickr | CC BY-SA 2.0

A farmer in Hohhot, Inner Mongolia, China, was taken aback when one of his sheep gave birth to a two-headed lamb. It has been stated that the lamb is in good health and is being cared for by its mother despite the abnormality that has been observed on it.

The lamb reportedly possesses four eyes, two mouths, and two noses, as reported by Metro News. It’s remarkable that it’s able to roam around and nurse from its mother at the same time.

4. Two-headed blue shark embryo

A fisherman found a two-headed blue shark embryo in the Indian Ocean in 2008, showing that sharks can have multiple heads. In 2011, researchers found conjoined twins in blue sharks caught in the Gulf of California and northwestern Mexico.

Blue sharks are known to have many offspring, with up to 50 infants born in a single pregnancy, which adds to the species’ higher incidence of two-headed embryos. 

These examples show that two-headed embryos can occur in various species of sharks. These findings help us understand how sharks can have multiple heads and give us more information about their growth and biology.

5. Sorte the turtle

Two-headed turtle
Two-headed turtle | image by jc.winkler via Flickr | CC BY 2.0

Two-headed turtles are also popularly known for this phenomenon. One of them, Sorte, which translates to “luck” in Portuguese, was just born alive at a Dutch breeder’s facility. According to veterinarians, it had a high chance of leading a long and healthy life despite the turtle having one shell but two heads and two tails. 

The CT scan showed that Sorte has four front feet and two air pipes but has one heart and one intestinal system. Sorte’s single heart and stomach mean that eating is never a problem, but two heads might be a problem if he’s in the wild.

6. Wisconsin’s two-headed goat

A two-headed goat was also born on the farm of the Nueske family in Wittenberg, Wisconsin. At first, the family was worried that the animal might not make it. However, they took the goat to a clinic, and the scans showed that it was a healthy baby goat.

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According to Daily Mail, the goat has two skulls that are fully formed and fused to the spinal cord. Its heart, lungs, and limbs also work well. Despite having a pair of almost everything else, it only has one stomach.

Humans are no exception

Abby and Brittany Hensel, conjoined twins from the United States who have drawn media attention for their unusual condition, are one of the well-known cases of polycephaly in humans.

They have a single torso with two heads attached to it, yet despite this, they have a high degree of symmetry, which makes them appear to be one body with uniform dimensions. Each twin possesses a heart, stomach, spine, pair of lungs, and spinal cord, and they control one arm and one leg each.

Growing Up

The twins had to cooperate with each other to learn activities like crawling, walking, and clapping during their infancy until they could perform tasks on their own. They can also eat and write at the same time. 

Doctors decided not to attempt surgical separation of the twins at birth because they believed that the chances of both surviving the operation were low. Their parents chose against separating them because they thought that living together as conjoined twins would improve their quality of life more than if they lived separately as they grew and developed abilities. 


In conclusion, animals with two heads, also known as polycephalic beings, are a rare and fascinating phenomenon in the animal kingdom. They can occur due to the incomplete splitting of embryos or the fusion of separate embryos.

While these animals capture our attention and curiosity, they face numerous challenges in their survival and development, and having multiple heads usually has lower chances of survival and reproduction than those with a single head.

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