The advantages of exoskeletons include enhanced leverage for muscular movements and protective covering for muscles and internal organs, while their disadvantages include heightened vulnerability during the molting process and restrictive in terms of sizes and weights. Exoskeletons are the stiffened, resilient structures that form the external covering of arthropods. The members of Phylum Arthropoda, having insects as the largest group, are the most diverse organisms on Earth.
The exoskeletons, also referred to as "integuments," are divided into four functional sections: epidermis, basement membrane, procuticle and epicuticle. The epidermis secretes the cuticle layers and forms a portion of the basement membrane, which separates the exoskeleton from the main body cavity. Directly below the epidermis lies the procuticle, consisting of a tough fibrous and protein-based substance called chitin. The chitin-rich procuticle either develops into rigid, outer layers called "exocuticle" or into soft, inner tiers called "endocuticle."
The epicuticle, located on the topmost area of the cuticle layers, guards against foreign invasion. This region has an innermost stratum called the "cuticulin layer" that contains lipoproteins and fatty acids. Another layer made up of wax molecules occupies the area above the cuticulin layer. The wax serves as an impermeable barrier against dehydration. The majority of insects often have another protective layer called a "cement layer" that prevents the waxy material from being abraded. Although the materials comprising the exoskeleton are relatively light, the size of arthropods are limited by this structure and they are forced to constantly shed it.