Where is the only place that an exoskeleton is thin and soft?

Question: Where is the only place that an exoskeleton is thin and soft?

If you are fascinated by the amazing diversity of animals with exoskeletons, such as insects, spiders, crabs, and lobsters, you might wonder how these creatures manage to move their rigid bodies. Exoskeletons are external coverings that provide support, protection, and attachment for muscles. They are made of different materials, such as chitin, calcium carbonate, or silica, depending on the animal group. Exoskeletons are usually hard and strong, but they also have some drawbacks, such as limiting the growth and size of the animal.

However, nature has found a clever solution to overcome these challenges: joints. Joints are the places where the exoskeleton is thin and soft, allowing for flexibility and movement. Joints can be found between the plates and cylinders that make up the exoskeleton of arthropods, the largest group of animals with exoskeletons. At these junctions, the exoskeleton lacks the hardening layer called the exocuticle and is folded to create creases. These creases act like hinges that enable the animal to bend and extend its limbs and body segments.

Joints are essential for the locomotion and survival of animals with exoskeletons. They allow them to walk, run, jump, fly, swim, dig, and grasp objects. Joints also enable them to sense their environment and communicate with other animals through sounds, vibrations, or gestures. Without joints, animals with exoskeletons would be stiff and immobile.