Final answer:
Arthropods undergo molting to shed their exoskeleton and grow, which involves vulnerability but is essential for their development and the success of their diverse species.
Step-by-step explanation:
During molting, arthropods shed their exoskeleton and secrete a larger one. This process is essential for arthropods to grow, as their hard exoskeletons do not expand. The exoskeleton is made up of layers, including the chitinous procuticle which consists of an exocuticle and an endocuticle.
As arthropods grow, the exoskeleton must be periodically shed, allowing for a new, larger exoskeleton to harden. This ecdysis process is risky because the arthropods are vulnerable until their new exoskeleton hardens, but it is a necessary part of their life cycle that allows for size increase and morphological changes. The high success and diversity of arthropod species, such as insects, spiders, and crustaceans, can be attributed to their ability to molt and adapt physically through this unique process.