Here's why:
* Chitin's primary function: Chitin is a tough, flexible polysaccharide that forms the structural component of exoskeletons in many animals, like insects, crustaceans, and fungi. It provides support, protection, and a rigid outer layer.
* Preventing water loss: While chitin is a strong material, it's not inherently waterproof. It's the wax layer found on top of the chitinous exoskeleton that provides the primary water-proofing mechanism. This waxy layer acts as a barrier against water loss.
* Other adaptations: Some animals, like insects, also have special adaptations like spiracles (breathing holes) and a closed circulatory system to conserve water.
In summary, chitin contributes to the structural integrity of the exoskeleton, but the wax layer on top of it is responsible for preventing water loss and protecting animals from drying out.