The key difference between carapace and plastron is that carapace is the dorsal part of the shell while plastron is the ventral part of the shell of an animal, especially a crustacean.
Arthropods have an exoskeleton or a shell. Some vertebrates, especially tortoises and turtles, also have an exoskeleton. The exoskeleton protects the animal body. Moreover, the shell or exoskeleton has two parts; a dorsal carapace and a ventral plastron joined each other on the sides. The dorsal or upper section of the shell is known as the carapace, while the lower or ventral side of the exoskeleton is known as the plastron. Generally, the carapace is convex in shape while the plastron is flat shaped. Also, the carapace covers the dorsal portion of the animal, while the plastron covers the ventral side of the animal. Therefore, both structures act as protective coverings. They are made from fused bones.
CONTENTS
1. Overview and Key Difference
2. What is Carapace
3. What is Plastron
4. Similarities – Carapace and Plastron
5. Carapace vs Plastron in Tabular Form
6. Summary – Carapace vs Plastron
What is Carapace?
The carapace is a hard protective covering that covers the dorsal side of an animal. Structurally, it is the dorsal or upper part of the shell/exoskeleton. The main function of the carapace is protection. It is a convex-shaped cover made from fused bones. Therefore, it is a bony or chitinous structure.
Figure 01: Carapace
Furthermore, a carapace can be seen in crustaceans, arachnids, and some vertebrates such as tortoises and turtles. In crustaceans, the carapace is a prominent and characteristic feature. The calcification of carapace differs among the different crustaceans. Carapace does not cover the head of the animal. It wraps all of the dorsal parts of an animal, which is known as cephalothorax. In some animals, the carapace is a decorative shell, while in some other animals, it is a camouflaging shell.
What is Plastron?
The plastron is the ventral part of the exoskeleton of some animals. It is a flat shell structure. The composition of the plastron is similar to that of the carapace. Therefore, it is made up of fused bones. Plastron protects the vital organs of turtles and other animals.
Figure 02: Plastron
In turtles, there is a difference in pigmentation in plastron between sexes. In addition, female turtles have a lighter plastron than males. Certain turtles exhibit a greater degree of plastron reduction. Moreover, the shape and the size of the plastron have a relationship with the degree of freedom and range of motion of the limbs in turtles.
What are the Similarities Between Carapace and Plastron?
- Carapace and plastron are protective coverings.
- They are parts of an exoskeleton of crustaceans and some other animals.
- Compositions of carapace and plastron are similar.
- They are made of many fused bones.
- They are bony structures.
- They usually join one another along each side of the body.
- Pigmentation can be seen in both carapace and plastron.
What is the Difference Between Carapace and Plastron?
Carapace and plastron are two parts of the exoskeleton of some animals. The carapace is the dorsal surface of the shell, while the plastron is the ventral surface of the exoskeleton. So, this is the key difference between carapace and plastron. Moreover, generally, the carapace is a convex structure, while a plastron is a flat surface.
The below infographic lists the differences between carapace and plastron in tabular form for side by side comparison.
Summary – Carapace vs Plastron
The carapace is the dorsal part of the shell, while the plastron is the ventral part of the shell in a number of animals, including crustaceans and some vertebrates. Both carapace and plastron are bony structures that work as protective coverings. They join one another along each side of the body. Their compositions are similar. They are also made from fused bones. Thus, this summarizes the difference between carapace and plastron.
Reference:
1.“Turtle Shell.” Wikipedia, Wikimedia Foundation, 23 Sept. 2021.
2.“Carapace.” Wikipedia, Wikimedia Foundation, 14 Apr. 2021.
Image Courtesy:
1. “Penaeus diagram carapace” (Public Domain) via Commons Wikimedia
2. “Painted Turtle’s Plastron “belly shell” “By Ptarp – Own work (CC BY-SA 3.0) via Commons Wikimedia