sclerotised

Sclerotised is an adjective used in biology, particularly in entomology and mycology, to describe a tissue or structure that has become hardened and darkened. This process, known as sclerotisation, involves the deposition of a sclerotising agent, typically quinones, onto the protein and chitin matrices of the cuticle or cell walls. This chemical transformation results in a rigid, dark, and often waterproof material.

In insects, sclerotisation is a crucial step in the development of their exoskeleton. Newly molted insects have a soft cuticle, which quickly hardens through sclerotisation, providing structural support and protection against predators and desiccation. This process is particularly evident in the formation of hard body parts like the head capsule, thorax, and the elytra (hardened forewings) of beetles. The degree of sclerotisation can vary, leading to differences in the texture and color of insect cuticles, ranging from leathery to extremely hard and black.

In fungi, sclerotised structures, known as sclerotia, are hardy, dormant bodies. These are typically composed of aggregated fungal hyphae that have undergone a process similar to sclerotisation. Sclerotia serve as a means of survival during unfavorable environmental conditions, such as drought or cold, and can persist for long periods before germinating when conditions improve. Their tough, darkened outer layers protect the viable fungal tissue within.