Тела этих живых существ разделены на мужское и женское посередине

Their bodies are split in two right down the middle. They could help us understand how sex develops

From the right-hand side, Dr H. E. Schaef's chicken looked like any normal cockerel, with a bright red comb and a wattle. But from the left you would think it was a hen: its body was slighter and had plainer markings.

Even its behaviour was decidedly confused. The creature attempted to mount the other hens in the yard, yet also laid small eggs itself.

When it died, Schaef decided to prepare the bird for his table. Once the bird had been plucked, it was obvious that the right half of the skeleton was much bigger than the left. When Schaef opened the abdomen to remove the gizzards, he found both a testis and an ovary with a partially formed egg.

It was as if someone had cut a hen and a cockerel in half, and merged the two bodies seamlessly down the centre.

 

The left and right sides of a gynandromorphic chicken (Credit: Michael Clinton)

Keen not to waste it, Schaef proceeded to roast and eat the chicken. But once the meat had been stripped off the bones, he preserved the skeleton and passed it on to his anatomist friend Madge Thurlow Macklin. She wrote up the story in theJournal of Experimental Zoology in 1923.

Today, we call these creatures "bilateral gynandromorphs". Unlike hermaphrodites, whose gender-bending often begins and ends at the genitals, these animals are split across their whole bodies: male on one side, female on the other.

Nearly a century after Schaef enjoyed his strange meal, many more examples have been found. Their odd characteristics could explain some of the mysteries of sex, and how our bodies develop.

 

A gynandromorphic Kentish glory moth (Endromis versicolora): female on the left, male on the right (Credit: FLPA/Alamy Stock Photo)

Although Schaef's account is one of the most colourful reports, sightings of male-female chimera date back hundreds of years.

Unsurprisingly, courtship for these animals sometimes presents difficulties

On 7 May 1752, a Mr M Fisher of Newgate presented the Royal Society of England with a lobster of unique appearance, with "all the parts of generation double". Since then, scientists have added crabs, silk worms, butterflies, bees,snakes and various species of bird to the list of animals that can develop into bilateral gynandromorphs.

It's impossible to say exactly how common they are. 

THE FULL STORY BBC Earth