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Bird Skeleton: A Detailed Summary

Bird Skeleton: An Introduction

Last updated date: 17th Mar 2023
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Isn’t it fascinating to see lightweight birds fly to a greater height? Even though they are tiny creatures when compared to human beings. Apart from being lightweight, their bone density accounts for enabling them to fly at varying altitudes. Every vertebrate consists of a skeleton to aid in supporting and protecting internal organs. However, the bird skeleton has certain similarities and differences from other vertebrates. Let’s learn about bird’s anatomy and flying mechanism ahead.

Bird Skeleton Anatomy

The bird skeleton comprises wings, two feet, a beak, and a body covered with feathers. Most birds have four toes; however, the arrangement differs from species to species. Birds have bones that are pneumatized for structural rigidity. The number of bones differs among the species. Soaring and gliding birds have the maximum number of hollow bones. Diving birds have comparatively fewer hollow bones. Puffins and penguins do not have hollow bones. Bird skeleton diagrams can be used for better understanding.

Skull: The bird's skull is similar to the human skull in having a large cranium. It weighs about 1% of the total body weight. Their eyes also occupy a substantial volume of the skull. Tiny bones enclose the eyes termed sclerotic eye-ring. The skull consists of small bones that do not overlap. The skull structure has importance in feeding. These bones can move independently.

Ribcage: Ribs are connected by small bones, referred to as an uncinate process, to enable great support.

Vertebrae: Vertebrae range from 39-63. The vertebral articulation is heterocoelous. The breastbone, called the sternum, is keel-shaped. This shape is necessary to create a large surface area for flight muscles to attach. The bird's wing muscles are attached to the keel to permit the bird to fly. The flexibility and support to the neck is provided by cervical vertebrae, ranging from eight to twenty-five. Excluding the first cervical vertebra, the remaining ribs are attached. The thoracic vertebrae range from five to ten. The first thoracic vertebra is attached to the sternum while the ribs of cervical vertebrae are free.

The frontal thoracic vertebrae are fused and articulate with the notarium of the pectoral girdle. Six lumbar, five sacral-caudal, two sacral and one thoracic vertebra comprises the synsacrum. This structure gives the birds strength while in the resting stage. Caudal vertebrae follow the synsacrum. They range from five to eight. They provide structure to the tails. Pygostyle comprises five to six caudal vertebrae providing attachment for feathers and regulating flight.

Heart: Birds have big hearts and are powerful since flapping requires energy. They require the blood to hurry in their system to enable the flight muscles to work efficiently. This varies between the species and size of the bird.

Beaks: Birds have toothless beaks, thereby making them light. Some bones have diminished totally with the progress of evolution, for instance, in the tail.

Legs: The bird's front legs are covered in feathers that make up the wings. But they do not provide any mechanical strength. Feathers enable birds to stay warm and dry.

Bird Skeleton


Bird Skeleton


Bird Skeleton Wings

The bird wings enable them to lift the body at great altitudes. However, the types differ from species to species. Terrestrial birds have less number of wings or none at all, while aquatic birds have wings serving as flippers. The bird wing anatomy comprises the shoulders, forearm, and hand. The shape of the wing is important to determine flight capabilities. Bird wings are categorised into four types. These bird skeleton types of wings include elliptical wings, high-speed wings, high aspect ratio wings, and soaring wings with slots.

Bird Skeleton Flying Mechanism

Though the bird's bones are very tender, it is structurally strong to achieve flying at a great altitude and undergo pressure while flying. This is possible as the bones are fused. Hence, they have fewer bones as compared to mammals. They differ from humans in being able to open up both of their jaws. The keel provides the support to which a bird's wing muscles attach, providing adequate flight power.

Not every bird has a keel; some flightless birds lack a keel. In the absence of a keel, birds are not able to fly. The upper jaw moves through flexibility supplied by a hinge between the frontal and nasal bones. A hinge-like expression can move the lower jaw with the quadrate bone at the base of the jaw.

Birds have cavities termed air sacs to trap the maximum amount of oxygen they need. When the birds inhale, the oxygen flows into the air sacs. The air sacs push the air to the lungs, expelling the stale air. They have flexible necks. They have big hearts because flapping requires a lot of power. Birds have hollows termed air sacs to trap the maximum oxygen they need. When the birds inhale, the oxygen flows into the air sacs.

Interesting Facts

  • Birds have hollow bones, also called pneumatized bones. These comprise space for air.

  • The lungs spread all over their bones to enable the entry of oxygen while breathing. This adaptation enables the bird to have an increased energy supply during flight.

  • The myth associated with this hollow bone is that it makes the bird feeble. On the contrary, birds are bulkier than animals of similar size. They have dense bones, which makes the bones thin, rigid, and firm.

Important Questions

1. What makes bird skeletons special?

Ans: The major bones of a bird's limbs are hollow and have strengthening struts inside.

2. How durable are the bones of birds?

Ans: The findings on bone density presented here indicate that generally speaking, bird skeletons are stronger and more rigid in comparison to their weight than are those of small mammals, particularly rodents.

Key Features

  • The birds have exceptional muscle support. The corpse of a roasted chicken has a massive breastbone popping out like the keel of a boat.

  • This feature is unique to the birds as it grips the muscles needed for flight. However, birds that do not fly do not possess this bone.

  • The air sacs push the air to the lungs, expelling the stale air and reducing the skeletal mass to 13 %, making them light enough to fly.

  • The bird's wing muscles are attached to the keel to permit the bird to fly.

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FAQs on Bird Skeleton: A Detailed Summary

1. Why do birds have few bones?

Birds have few bones because they need solid bones yet are lightweight to fly. This is accomplished by merging small-sized bones and removal of others. The bones are hollow and have air spaces to enable them to fly quickly.

2. What bones are involved in the breathing mechanism in birds?

Birds have cavities termed air sacs to trap the maximum amount of oxygen they need. When the birds inhale, the oxygen flows into the air sacs. The air sacs push the air to the lungs, expelling the stale air.

3. How do birds fly even when there is a loss of feathers?

Birds constantly shed their feathers through a process called moulting. This could either be a gradual loss over a while or spontaneously. They ensure that while moulting they do not engage in activities that require a lot of energy.


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