Title:
The Dissection of an Avian Bird: Chicken.
Aim: To familiarise and compare the avian morphological and anatomical characteristics with the
humans.
Introduction
The birds are occupying all the biomes throughout the world with their different kinds of adaptive
lifestyles. Birds are found in the tropics as well as the Arctic regions. They live in the jungles,
forests, on mountain-tops, along the coasts, and villages, towns and cities. Birds are ranged in size
from the tiny hummingbird to the ostrich. They feed on seeds, nectar, insects, small animals, and
rotting fleshes (Otto & Towle, 1985, p.531). Some birds live in one place throughout their entire
lives while other birds can travel long distances to the favourable seasons and adequate resources or
food supplies. The nature of the natural selections caused the birds to adapt to life in the air, on the
water, and on the land.
The birds showed many differences in colours, sizes, diets and lifestyles but they all share these sets
of characteristics that distinguish them from the mammalians and other vertebrates. Birds have
feathers, thin or hollow bones, forelimbs (wings), two hind-limbs, and horny beak. The birds are
also different compared to the mammals (Otto & Towle, 1985, p.534). Birds have feathers, beak
(lack teeth), and lay eggs. They are able to float on the water and fly in the air. Birds excrete wastes
from only one opening which is through cloaca. The framework of this experiment is to explore the
basic avian morphological and anatomical characteristics. The hypothesis was made to investigate
and compare the organ systems of birds to those of humans.
Research Question: What are the anatomical physiologies of the chicken? Are the birds having
similar or different organ system to those of human? Are they all related to humans’ organ systems?
Hypothesis: The birds’ anatomical features or organ systems have similar to the humans.
Materials: The following materials were used during experiment; Live chicken, dissecting tray,
small knife, scalpel blade, cotton wool, 50% alcohol, hot water, dish, gloves, scissors, spatula and
paper towel.
Procedures
A live chicken was taken from the carton and placed it on the dissecting tray in the laboratory.
The morphological structures of a chicken such as beak, scales, feathers, and combs and dorsal,
ventral, caudal and cranial were carefully examined before the anaesthetization. The observed
morphological features were recorded in the data sheet.
The chicken was anaesthetised and made it to sleep by using 50% alcohol soaked in cotton wool.
Then it was placed in the dish of hot water for de-feathering or skinning of the feathers. It took two
to three minutes for the feathers to become loosen. The feathers of the chicken were removed and
the chicken was cleaned and washed with tap water for actual dissection.
The cleaned chicken was placed again on the dissecting tray. The chicken was then cut open by
using small knife, scalpel blades and small scissors. The anatomical characteristics of the chicken
were examined with the help of a laboratory instructor. The organ systems including digestive
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By: Samson Kunuyobu, 2019.vertebrate biology.uog
system, respiratory system, reproductive, excretory and circulatory system of the chicken were
observed and recorded in the data sheet.
Observation of the Result
Part A: Morphological Structures of Chicken
Table 1: The external features and descriptions of the dissected chicken
No. EXTERNAL FEATURES
1
Beak
2
3
4
5
6
7
8
Feathers
Skin
Scales
Filoplumes
Wattle
Comb
Nails
DESCRIPTION AND FUNCTIONS
Birds have beaks instead of teeth. The beak is used for eating
and drinking, as well as in self-defence and protection from
other animals.
The outer covering of bird’s body which function to protect
bird from external harm
It is much like humans with exception of plumage production
The outer covering of a bird’s body located on the legs and
feet. Scales function to protect the bird from external harm
Hair-like structures located at the base of the feathers
A red growth underneath the beak which works with comb.
An excess of skin on top of the chicken’s head.
Birds have nails at the tip of their feet for scratching on the
ground and protection from external harm
Part B: The Anatomical Structures of the Chicken or bird.
LUNGS
Photo by: Kunuyobu, S, 2019
Figure 1.1: A diagram showing the circulatory system of chicken
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By: Samson Kunuyobu, 2019.vertebrate biology.uog
LUNGS
Gall Bladder
Photo by: Kunuyobu, S, 2019
Figure 1.2: A diagram showing Respiratory system of the chicken
Proventriculus
Photo by: Kunuyobu, S, 2019
Figure 1.3: A diagram of Digestive system of chicken
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By: Samson Kunuyobu, 2019.vertebrate biology.uog
DISCUSSION
The morphological features of the dissected chicken were observed as shown above (table 1). The
outstanding external features were clearly observed are feathers, scales, filoplumes, beak, comb and
wattle. The other external characteristics are feet with nails, flexible neck, wings and legs with the
scales. These morphological characteristics protect the bird or chicken from the external harm. This
report has identified some descriptions and functions of the chicken’s morphological features as
shown in the experimental result section. De Britto (2019) mentioned that the birds have beaks as
opposed to teeth. The beak of the birds is used for eating and drinking, as well as in self-defence
and protection from other animals.
The second part of the experiment was the dissection of chicken for the anatomical studies of the
birds. The some organ systems of the chicken were identified as shown in the figures above (fig.
1.1, 1.2, & 1.3). The other organ systems were also observed but they were not really examined
properly due to the limitation of the time.
The heart and other related organs were observed that make up the circulatory system in birds.
However, the heart was clearly observed in dissected chicken, the related organs such as blood
vessels were not really noted during the dissection. The heart pumps blood throughout the body to
deliver oxygen and nutrients to tissues and to remove carbon dioxide and metabolic waste from
tissues. Birds have few blood vessels and no respiratory surfaces.
A bird's heart structure is similar to the human’s heart (figure 1.1 & 1.2). It has a four chambered
heart muscles that pumps blood throughout the body. A bird's heart weighs up to twice as much as
that of a mammal of equal size because flying is strenuous. Smaller birds and mammals lead fastpaced lifestyles and generally have faster heart rates than large ones. The birds’ normal heart rate is
100 to 200 beats per minute while humans’ 70 beats per minute at rest.
Birds have respiratory system adapted to meet the great demand for oxygen during flight. The lungs
used both by birds and mammals for the exchange of oxygen and carbon dioxide between the blood
and air. The birds have smaller lungs than those of mammals as shown in figure 1.2. The birds
normally breathe rapidly during flight. The lungs of birds are out-pocketing filled with air. The
lungs extend between various organs and penetrate certain bones. The sacs are transparent and
noticeably thin-walled which act a cooling system and giving the lungs a constant flow of fresh air
in birds. The birds’ respiratory system is vastly different from the humans. The birds lack
diaphragm to inflate and deflate the lungs. Instead, birds have air sacs to inflate the lungs. Gas
exchange occurs in the avian lung and the air sacs function to move air in and out of the respiratory
system
Birds have well-developed digestive system to meet the heavy energy demands. The mouth of the
birds consists of toothless beak, tongue and taste buds used for gathering foods and tearing the
fleshes from other animals. The food passes down the oesophagus into the crop as shown in the
figure 1.3 above. The food then passes into the first stomach or Proventriculus for digestion. The
food continues to travel into the second stomach or gizzard, and into the small and large intestines.
The waste products leave the body through a cloaca (see fig.1.3). The birds’ digestive system is
greatly different from the humans. Birds have toothless beak, crop, Proventriculus, and gizzard
which are different from those of humans.
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By: Samson Kunuyobu, 2019.vertebrate biology.uog
Other organ systems inside a chicken, including reproductive and urinary system were also
observed but there were not carefully identified their locations because of the time limitations
during the experiment. The kidneys, ureters and cloaca were observed in that dissected chicken in
the laboratory. The humans have urinary bladder but birds have no urinary bladder. The
reproductive organs such testes, ovary, oviduct, vasa deferentia, and seminal vesicles were not
studied carefully due to time limitation. Though birds have internal fertilization like humans, birds
lay eggs and incubate them. In most female birds, there is only the left ovary and oviduct lying on
the ventral side of the left kidney. The female humans have two ovaries located on both sides of the
fallopian tubes (Otto & Towle, 1985). Birds have cloaca which accommodates ducts from the
kidneys and reproductive organs for the waste disposal and reproduction respectively.
CONCLUSION
The birds have some similar characteristics with the mammals as the vertebrates. However, they
show vast difference in organ systems with humans. The main difference about the birds compared
to humans are feathers, lack teeth (beaks), lay eggs, float and fly and excrete wastes from only one
cloacal opening. The main organ systems of chicken discussed are circulatory system, respiratory
system, digestive system, reproductive system and urinary system. The morphological and
anatomical features are figured them out and compared them accurately to those of humans. The
basic avian chicken’s external and anatomical characteristics were familiarised and compared with
the human organ systems. Hence, the aim of the experiment was successfully achieved with few
limitations. The experimental errors can be fixed for the successful and accurate results in similar
experiments in the future.
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By: Samson Kunuyobu, 2019.vertebrate biology.uog
REFERENCE
1. Otto, J.H., & Towle, A. (1985). Modern Biology. Holt, Rinehart and Winston Publisers, NY:
USA.
2. De Britto, S. (2019). BI 346: Vertebrate biology: Phylum Chordata-Class Aves, (power
point). Retrieved from students’ saver 2019 lecture notes.
3. All about Bird Anatomy (2019). The Cornell Lab of Ornithology. Retrieved from
https://academy.allaboutbirds.org
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By: Samson Kunuyobu, 2019.vertebrate biology.uog