Cuticula

Cuticula is a term used in biology to denote the outer protective layer secreted by epidermal cells in a variety of organisms. It is commonly equated with the cuticle, though the usage and scope can vary by group. The word derives from Latin cuticula, a diminutive of cutis (skin).

In arthropods such as insects, crustaceans, and arachnids, the cuticle forms the exoskeleton. It is a multilayered structure usually comprising the epicuticle, exocuticle, and endocuticle. The matrix is primarily chitin and structural proteins, which may be sclerotized in hardened forms. The epicuticle contains lipids and waxes that reduce water loss. The cuticle is secreted by the epidermis and is periodically shed and renewed in a process called ecdysis during growth.

In nematodes and some other invertebrates, the cuticle is a flexible extracellular matrix produced by underlying hypodermal cells and rich in collagen-like proteins. It serves as a protective covering and assists in movement, and is also renewed during molts.

In plants, the outer protective layer covering aerial organs is commonly called the cuticle; some older literature uses cuticula. The plant cuticle, composed mainly of cutin with embedded waxes, forms a hydrophobic barrier that minimizes water loss, protects against pathogen entry, and interacts with stomata to regulate gas exchange. Its thickness and composition vary with species, developmental stage, and environment.

Knowledge of cuticula properties informs fields from pest management and forensics to postharvest biology, where wax coatings (natural or applied) influence durability, appearance, and shelf life of plant and fruit tissues.