Skeletal system of amphibians|Axial and appendicular skeleton|BSc and MSc Zoology|Detailed Notes

Описание: Skeletal System of Amphibians – Detailed Explanation

The skeletal system of amphibians provides support, protection, and movement. It shows special adaptations for life both in water and on land. It is divided into two main parts:


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1. Axial Skeleton

This includes the skull, vertebral column, and sternum.

Skull

Lightweight and somewhat flattened.

Cartilaginous in larvae and mostly bony in adults.

Cranium is small and has fewer bones compared to higher vertebrates.

Has two occipital condyles for articulation with the vertebral column.


Vertebral Column
Divided into regions:

Cervical (1 vertebra): Allows head movement.

Trunk (6 to 15 vertebrae): Supports the body.

Sacral (1 vertebra): Attaches pelvic girdle.

Urostyle: A rod-like bone formed from fused caudal vertebrae, especially in frogs.


Sternum

Cartilaginous or bony structure.

Supports the pectoral girdle and protects internal organs.

Absent in some species like caecilians.



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2. Appendicular Skeleton

This includes limbs and girdles (pectoral and pelvic).

Pectoral Girdle

Composed of scapula, coracoid, and clavicle.

Supports the forelimbs.

Not directly attached to the skull.


Pelvic Girdle

Made of ilium, ischium, and pubis.

Fused with the vertebral column through the sacral vertebra.

Very strong, adapted for jumping and movement.


Limbs

Typical tetrapod pattern.

Forelimbs: Humerus → Radius & Ulna → Carpals → Metacarpals → Digits (usually 4).

Hindlimbs: Femur → Tibia & Fibula (fused in frogs) → Tarsals → Metatarsals → Digits (usually 5).

In frogs, hindlimbs are long and muscular for leaping and swimming.



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Limbless Amphibians (Gymnophiona)

Limbs and girdles are absent.

The body is elongated with many vertebrae, adapted for burrowing.



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Summary Table

Structure Function

Skull Protects brain, supports sensory organs
Vertebral column Supports body, aids movement
Pectoral girdle Supports forelimbs
Pelvic girdle Supports hindlimbs
Limbs Locomotion (jumping, walking, swimming)
Urostyle Aids in jumping (especially in frogs)



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