Mutation or ecdysis is a process that occurs in arthropods and is characterized by the exchange of the skeleton of these animals to ensure their growth. This process is essential, as these invertebrates have an external skeleton, which makes continuous growth impossible.
→ exoskeleton of arthropods
One of the most striking characteristics of an arthropod is the presence of a chitinous exoskeleton or cutin that covers its entire body. Despite being rigid, the animal manages to move thanks to its joints. Due to this property, the phylum received the name of Arthropoda, which means «jointed feet».
The exoskeleton of arthropods is formed by an epicuticle and a procuticle composed of an external exocuticle and an internal endocuticle. The epicuticle is formed by proteins and wax, while the procuticle is rich in chitin.
→ How does molting occur in arthropods?
The exoskeleton has several advantages with regard to support, protection against water loss and predators, and even movement. Nonetheless, represents a serious problem when it comes to growthso it is periodically eliminated to allow the animal’s body to grow.
Don’t stop now… There’s more after the publicity 😉
For molting to occur, the animal begins to produce inactive enzyme precursors at the base of the skeleton. The epidermis detaches from the skeleton and production of a new epicuticle begins. Inactive enzymes are activated and begin to digest the endocuticle. The epidermis produces a new procuticle, which lies under the old one. It is noticed, then, that the arthropod is trapped inside two exoskeletonsthe old and what is forming.
The ancient skeleton begins to break down at specific, predetermined points called fracture lines or ecdysis lines. The animal leaves its old skeleton, already involved by the new one, however, this one is soft, which leaves the animal unprotected. Furthermore, the exoskeleton that was just formed it’s all wrinkled and, over time, it will stretch to accommodate the new animal, now a little bigger. This adaptation of the exoskeleton to the new body is possible thanks to the blood pressure in the animal’s organism. Hardening, in turn, occurs after the stretching of the exoskeleton has been completed.
By Ma. Vanessa dos Santos