Final answer:
Cephalon, thorax, and pygidium are body segments of arthropods, particularly trilobites, and relate to the head, midsection, and tail section, respectively. Arthropods have segmented bodies with a cuticle exoskeleton and specialized jointed appendages, which are key features for their physiological processes.
Step-by-step explanation:
The terms cephalon, thorax, and pygidium are related to the body segments of arthropods, specifically a group known as trilobites. Trilobites are extinct marine arthropods that had their bodies divided into three major sections: the cephalon or head, the thorax or midsection, and the pygidium or tail section. Additionally, arthropods, including insects, have bodies comprised of segmented sections that are often fused into functional groups called tagmata. For insects, the tagmata typically include the head, thorax, and abdomen. The thorax usually bears the wings and three pairs of legs in hexapods, such as insects. This segmentation and organization of body parts is crucial for the various physiological processes that arthropods perform, such as digestion, respiration, and movement.
The outer layer of an arthropod's exoskeleton is called the cuticle, which is composed of two layers: the outer exocuticle and the inner thicker layer. This cuticle is essential for protection and water resistance in arthropods. Furthermore, in terms of functionality, the morphological features of arthropods allow for a diversity of actions, including the jointed appendages that have been specialized for a myriad of functions.
Insect anatomy also includes well-developed systems for digestion, respiration via spiracles and tracheae, circulation, and nervous coordination. The Hexapoda comprise the class of arthropods with six legs. Notably, incorrect is the statement that the trachea is part of the digestive system; it is in fact part of the respiratory system in insects.