Biology

Difference Between Endoskeleton and Exoskeleton

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Main Difference

The main difference between Endoskeleton and Exoskeleton is that Endoskeleton is known as the toughest part, which is present in a body, whereas Exoskeleton is known as the toughest part which is present out of the body.

Endoskeleton vs. Exoskeleton

Endoskeleton usually mentions the internal skeleton of the body, such as a cartilaginous skeleton or the bony skeleton of the vertebrates. On the other hand, exoskeleton mentions the exoskeleton or bone armor of the body, like the arthropod’s chitinous skeleton. The endoskeleton is composed of phosphorus and calcium; on the contrary, the exoskeleton is composed of the chitinous cuticle, scales, or calcified shells.

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The endoskeleton is located inside the organism’s body; on the flip side, the exoskeleton is located outside the organism’s body. The endoskeleton is found in higher vertebrates; on the other hand, the exoskeleton is found in arthropods.

The endoskeleton is normally made up of bones and cartilages, while the exoskeleton is typically made up of chitin or mostly calcium compounds. The endoskeleton is considered as a living structure, whereas exoskeleton is considered as the non-living structure.

The development of the endoskeleton takes place from the endoderm; on the contrary, the development of exoskeleton takes place from the ectoderm. The endoskeleton normal grows with the growth of the body; on the flip side, the exoskeleton has to be shed with time because it usually does not grow with the growth of the body.

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The flexibility of the endoskeleton is considered more than the exoskeleton, while the exoskeleton is considered less flexible. The endoskeleton provides a specific structure for the attachment of muscles to the body; on the other hand, the exoskeleton provides a structure in which the wings of insects are joined with the exoskeleton through muscles.

The endoskeleton protects from predators by moving away with the use of their muscles, which are attached to their bones, while animals having exoskeleton protected themselves from their predators by using skeleton modifications such as camouflage colors or spines.

The endoskeleton of vertebrates takes a long time to recover with cartilage, and then bone being placed; on the other hand, the exoskeleton can be recover or replaces quickly by using chitin and protein, or by using deposited calcium carbonate. The endoskeleton contains a blood supply, whereas the exoskeleton does not have this case.

Comparison Chart

EndoskeletonExoskeleton
The skeleton, which is found inside the body of an animal/vertebrates, is known as an endoskeleton.The skeleton which is found and developed outside of the body of animals is known as an exoskeleton.
Refers To
Mentions the internal skeleton of the body such as a cartilaginous skeleton or the bony skeleton of the vertebratesMentions the external skeleton of the body such as the chitinous skeleton in arthropods
Structure
Composed of phosphorus and calciumComposed of the chitinous cuticle, scales, or calcified shells
Internal/External
Located inside the organism’s bodyLocated outside the organism’s body
Found In
Found in higher vertebratesFound in the arthropods
Composition
Made up of bones and cartilagesMade up of chitin or mostly calcium compounds
Living/Non-living
Considered as a living structureConsidered as the non-living structure
Development
The development takes place from the endodermThe development takes place from the ectoderm
Growth
Normally grows with the growth of the bodyHas to be shed with time because it usually does not grow with the growth of the body
Flexibility
The flexibility is considered more than the exoskeletonConsidered less flexible
Attachment of Muscles
Provides a specific structure for the attachment of muscles to the bodyProvides a structure in which the wings of insects are joined with the exoskeleton through muscles
Protection from Predators
Protects from predators by moving away by using their muscles which are attached to their bonesProtected themselves from their predators by using skeleton modifications such as camouflage colors or spines
Repair and Replacement
Takes a long time to recover with cartilage and then bone being placedCan recover or replaces quickly by using chitin and protein, or by using deposited calcium carbonate
Blood Supply
Contains a blood supplyDoes not contain a blood supply

What is Endoskeleton?

The internal bony or cartilaginous skeleton of the animal is known as an endoskeleton. All vertebrates consist of the endoskeleton, for instance, amphibians, fish, reptiles, birds, and mammals.

To serve as the internal support system in the animal’s body is the main function of the endoskeleton. The endoskeleton is considered more flexible than the exoskeleton, and it mainly provides protection and support to the internal organs.

The endoskeleton is typically composed of bones and cartilages, and also contains blood supply. The endoskeleton of vertebrates takes a long time to recover with cartilage, and then bone being placed.

The endoskeleton is composed of bones and cartilages such as in cartilaginous fishes; it is made up of cartilages except for bones. The bone comprises concentric circles of bone cells known as osteoblasts, and calcium phosphate is present in the composition of its extracellular matrix.

What is Exoskeleton?

The skeleton which is present outside of the body, such as the chitinous skeleton of arthropods, is known as an exoskeleton. The arthropods mainly consist of an exoskeleton such as Chilopoda, insects, crustaceans, Diplopoda, arachnids.

The exoskeleton is also helpful in providing protection and support to the internal organs of the body. The insect’s wings are joined directly by their muscles with the exoskeleton. Though, the exoskeleton sheds many times during the lifetime of an organism in a process known as molting because it does not grow with the growth of the body.

The exoskeleton is also present on mollusks in the form of hard, outer protective covering, which is made of calcium compounds except for chitin. The reptiles, including turtles, contain a hard exoskeleton like mollusks. The reptiles and mollusks do not shed their exoskeleton during their growth and development.

Key Differences

  1. The endoskeleton originates in the vertebrates; on the other hand, the exoskeleton is present in arthropods.
  2. The endoskeleton is found inside the body of organisms; on the contrary, the exoskeleton is found outside the body of living organisms.
  3. The endoskeleton is fabricated with bones and cartilages; on the flip side, the exoskeleton is made up of chitin or deposited calcium compounds.
  4. The endodermis responsible for the production and development of endoskeleton, while the ectoderm is responsible for the development of the exoskeleton.
  5. The endoskeleton is considered a living structure because it grows with the growth of the body; conversely, the exoskeleton is considered non-living because it does not grow with the growth of the body, and it must have to be shed off from the body of an organism over time.
  6. The endoskeleton provides the safety of the predators by running with the help of their muscles, which are attached to the bones; on the contrary, the exoskeleton protects by having camouflage colors or rocky spines on the surface of the body.

Conclusion

The above discussion concludes that the endoskeleton and exoskeleton are the two specific types of hard structures that provide animal structural support. The endoskeleton is known as the internal skeleton of an animal, which is composed of calcium and phosphate, whereas the exoskeleton is the outer region/skeleton of an animal, which is composed of chitin.

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Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White