What is a Chicken? A Look at the Bird We Love to Eat

A chicken is a domestic junglefowl with characteristics of wild species like the Ceylon jungle fowl and the gray jungle fowl from Southeastern Asia. An adult male bird is a cockerel or rooster, while a female adult chicken is called a hen.

Chickens come in various varieties, breeds, classes, and strains. These birds also have different feather coloration, ranging from brown, white, gray, and black.

Anatomy of a Chicken

Chickens have a different anatomy from humans. Furthermore, a chicken’s anatomy comprises two parts, the external chicken anatomy and the internal part of a chicken’s anatomy. Here is a rundown of chicken anatomy.

Chicken’s Anatomy External Part

  • Feathers- Chickens have feathers covering the most significant part of their bodies. Feathers help protect chickens’ bodies from extreme heat and cold. Chickens have different types of feathers. Some feathers adorning a chicken’s body include semiplumes, contour feathers, filoplumes, and down feathers.
  • The beak– The beak is the first notable part of the outer part of a chicken’s anatomy. It’s the horny projection of a chicken’s jaw, which the bird uses for feeding and drinking. For feeding, your chicken will rely on its beak to break plant material, fruits, and several foods it chooses to include in its diet. The chicken will use its beak to drink and swallow water down its digestive system. Chickens also use their beaks to fight each other and fight against predators.
  • Comb– The comb is the fleshy outgrowth on a male chicken’s head. Hens and roosters have combs, although roosters have bigger combs than females. The comb helps a chicken regulate its temperature during hot weather.
  • Wattles-Wattles are the soft meat hanging below the two sides of a chicken’s beak. Wattles help chickens keep cool during hot weather. They are also a sign of sexual maturity.
  • Nostrils– A chicken’s nostrils are close to the joint place of the comb and the beak. Nostrils help chickens inhale and expel air. They serve a similar purpose to the human nostrils.
  • Earlobes-They are the hanging skins from the chicken’s ears. Chickens’ earlobes have different colors, depending on the breed. Earlobes aid chickens in hearing.
  • Wings-Chickens have two wings with multiple flight feathers. Chicken wings have secondary and primary feathers. While chickens don’t fly far like most birds, they still need wings for survival. For instance, wings help chickens maintain short flights while climbing or jumping over obstacles, such as fences or walls. Chickens also use their wings for display.
  • Tails– Both hens and cocks have tails. Chickens rely on their tails to maintain balance while flying and walking. Chickens also use their tails for display or communication. For instance, an adult rooster can lift its tail to warn rival roosters or exhibit dominance.
  • Vent– the vent is the small opening on a chicken’s backside. Chickens use their vents to lay eggs and expel waste.
  • Spurs-Spurs are sharp-horn protrusions growing on a chicken’s legs. Chickens use their spurs for self-defense and fighting. Roosters have more prominent spurs than hens.
  • Legs– chickens have two legs consisting of hocks, joints between a chicken’s shank and the thigh. A chicken’s leg also has a shank, the part below the hock. Chicken legs have toes that have claws. The number of toes can vary depending on a chicken’s breed. Some breeds, like Silkies, have up to five toes, while the average chickens have three toes. Chickens use their legs for walking and scratching the ground while searching for food.

Chickens’ Internal Anatomy

Chickens have a complex internal anatomy that is different from their external anatomy. These are the various parts that comprise the internal part of a chicken’s anatomy.

  • Esophagus– It is the flexible tube connecting a chicken’s mouth with its entire digestive tract. The esophagus carries water and food from a chicken’s mouth to the crop.
  • The crop-The crop is the extension of a chicken’s esophagus, sitting outside the bird’s body cavity in its neck region. It stores the water and feeds the chicken consumes.
  • The thoracic cage/ rib cage– The rib cage protects the organs inside a chicken’s chest, including the lungs and heart.
  • The heart– The heart is a crucial part of a chicken’s internal anatomy. A chicken’s heart is the muscular organ that pumps blood all over a chicken’s body.
  • The lungs– The lungs play a crucial respiratory role in chickens, like in other creatures. Air exchange in chickens takes place in the lungs. The air sacs in the lungs help carry carbon dioxide and oxygen through the lungs.
  • Liver– A chicken’s liver plays an integral role in metabolism and digestion. The liver also produces various proteins, enzymes, and blood proteins.
  • The gall bladder-This is the small sac containing green fluid known as bile. It sits under the liver. The gallbladder stores the bile, which helps digest the fats and foods a chicken consumes.
  • The small intestine-The small intestine is a vital part of a chicken’s gastrointestinal system. It consists of three parts, the ileum, jejunum, and the duodenum.
  • The large intestine– The primary function of a chicken’s large intestine is to absorb water and dry out the indigestible foods a chicken consumes. The large intestine also eliminates waste products.
  • The ovary– All egg-laying hens have ovaries containing vast amounts of egg yolks.
  • Papilla– This is a sexual organ in roosters that sits inside the walls of the cloaca. The organ looks like a tiny bump and serves a similar purpose to a human penis.

Characteristics of a Chicken

Chickens come in various colors and sizes. These birds lay eggs ranging from olive green to pure white, blue, and dark brown. Adult female chickens lay a varied number of eggs annually. Some hens, for instance, can lay around 150 eggs annually, while others can lay over 300 eggs.

They are improved chicken breeds that farmers raise for meat and eggs. Improved breeds can weigh up to 4kg when they are a couple of weeks old. Dual-purpose chickens are suitable for eggs and meat.

Chickens have different maturity rates depending on environmental factors, nutrition, and breed. Chickens mature at around six months old on average. Male chickens become cocks or roosters after full maturity.

Pullets are female chickens that haven’t reached adulthood. A chicken’s physical characteristics differ by breed. The breed affects all the physical attributes of a chicken, from size to egg production, meat production, and feather quality.

Some physical characteristics of chickens include combs, wattles, and earlobes. Some breeds have side-by-side combs, while others have single combs. Chicken wattles differ in size since some chickens have bigger wattles than others. Chickens have earlobes of different colors. Some have white, red, blue, and black earlobes.

The Lifespan of a Chicken

Chicken have varied lifespans. These birds live for around three to seven years. Chickens that get excellent care can live between ten and twelve years. However, chickens have a vague lifespan since some factors, like diseases and predators, can significantly shorten their lifespans.

Classifications of Chickens

Like other birds, chickens come in various breeds and strains. Learning about the different chicken classifications is vital for successful chicken farming. All chickens are members of the kingdom Animalia. They belong to the Phasianidae family of birds.

All chickens originating from a specific place and having similar characteristics belong to the same family. Chickens with the same physical features, size, and shape belong to the same breed.

For instance, Leghorns and Minorca chickens belong to the same breeds because they have similar sizes, physical characteristics, and shapes.

Origin of Domesticated Chickens

Chicken domestication has existed for 7,000 to 10,000 years, specifically in Southeast Asia. The domestication and distribution of chickens have been occurring rapidly and becoming widespread, thanks to these birds’ ability to provide eggs and meat without competing for scarce human food sources.

chicken comb types

Breeds and Varieties of Chickens

Chickens with the same size, physical characteristics, and shape belong to the same class and breed. There are thousands of domestic chicken breeds. Some physical features that distinguish these breeds include size, skin color, comb type, and plumage color.

Some common breeds include Rhode Island Red, Cornish Cross, and Leghorns. Chicken breeds can either be egg or meat producers. Some meat-producing breeds include Jersey Giant, Buff Orpington, Cochin, and Malay.

Egg-producing breeds include ISA brown, Leghorn, Marans, Plymouth Rock, Sussex, and Wyandotte. Poultry experts also classify breeds by origin. For instance, a breed like Asil chicken hails from Punjab, Indian Game from England, Delaware Blue from the US, and Pekin chicken from China.

Chickens also belong to different varieties. You can detect a chicken’s variety from its feather color, feather pattern, and comb type. A variety is simply a subdivision of a chicken breed.

For instance, a breed like Wyandotte is available in several colors, including silver, laced, Columbian, and white. Each color variation of this breed represents a specific variety.

Class, Breed, and Variety of Chickens

The standard chicken breeds come in different classes. These classes include American, English, Mediterranean, Asiatic, and continental. The American chicken breed, for instance, includes breeds that originate from the US or Canada. These breeds are heavier than the standard breeds. They include Buckeye, Delaware, Jersey Giant, and New Hampshire.

Asiatic breeds originate from Asia. Some popular breeds in this category include Brahma and Cochin. Continental breeds originate from Europe, including France, Belgium, the Netherlands, and Germany. They include Barnevelder, Lakenvelder, Wellsummer, Polish and Marans.

The English chicken class consists of chickens originating from the UK and Australia. They include Cornish, Australorp, Sussex, and Orpington. Chickens that fall under the Mediterranean class hail from Spain and Italy. They include Leghorns, Catalans, Andulusians, and Anconas.

While these chickens may belong to the same breed, they tend to fit in different varieties. Take a breed like Ameraucana, which belongs to the American class of chickens. It’s available in multiple varieties: Black, brown, blue, and silver. The Yokohama breed is an Asiatic breed that comes in white and Red shoulder varieties.

The other popular Asiatic breed that comes in multiple varieties includes the Malay. They are white, black, red Pyle and black-breasted varieties of the Malay breed. Ancona is a widespread breed belonging to the Mediterranean class. It comes in two varieties, the rose comb and the single comb.

Strains of Chickens

Poultry experts also classify chickens into strains. A chicken strain is a family of chickens that results from selective breeding through internal insemination. Breeders create various strains for specific purposes, such as egg and meat production. Some common chicken strains include star cross white. The American strain is a product of the traditional English strains.

Chicken Sex and Age Classification

One of the best ways of classifying chickens is according to their sex and age. Here is how to classify these birds based on sex and age.

Cockerel and Rooster

A cockerel is a young rooster that is yet to reach sexual maturity. A rooster is an adult rooster that has reached sexual maturity.

Pullet and Hen

Pullet is a term that refers to a young hen that is yet to reach sexual maturity. Pullets are usually around six weeks to six months old. These young hens are yet to start laying. A hen is an adult female chicken that is over six months old. A hen is sexually active, and it has started laying.

Sexed Chicks and Straight-Run Chicks

Sexed chickens and straight-run chicks are popular terminologies in hatcheries. Sexed chickens are chicks you can tell their gender before purchasing them from the hatchery. Straight-run chicks are unsexed chicks whose gender is unknown, so it’s hard to establish the gender of such chicks.

Market Terms for Chickens

Chickens have different terms everyone purchasing or raising chickens ought to know. These are some market terms for chickens.

  • Broiler or Fryer– A broiler or a fryer is a young meat chicken between four and eight weeks old.
  • Roaster– A young bird of any gender ready for butchering when it’s around eight weeks old.
  • Stewing Chicken, Hen, or Fowl– Stewing chicken, hen, or fowl refers to an older chicken, especially an older hen that has ceased laying.


The chicken is undoubtedly the most common domesticated fowl. Chickens belong to different breeds, classes, and varieties. Chickens also have varied physical traits, temperaments, and sizes. Furthermore, chickens suit different purposes, including meat production, egg production, and ornamental purposes.

avatar James
Hey, I'm James, a hardworking homesteader for more than 30 years. I enjoy the feeling of accomplishment that comes from tending my flock. I've raised chickens and ducks for eggs and meat for many years. I also have experience with other poultry too. Learn more

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