Which of the following is NOT a characteristic of arthropods?

The choice regarding the presence of lungs as a characteristic of arthropods is the correct answer because most arthropods do not possess lungs. Instead, they generally utilize other respiratory structures such as gills (in aquatic species), book lungs, or tracheae to facilitate breathing. While some terrestrial arthropods, like certain spiders, possess structures akin to lungs, the majority rely on tracheal systems for gas exchange, which further emphasizes the diversity in respiratory adaptations rather than a general characteristic of all arthropods.

In contrast, the presence of three body regions—head, thorax, and abdomen—is a defining feature common to many arthropod groups, encompassing insects, arachnids, and crustaceans. Jointed appendages are another hallmark of arthropods, providing them with a wide range of movement and functionality. An exoskeleton made of chitin is a significant protective feature that supports and protects the body, making it a consistent characteristic across different arthropod species. The discrepancy with lungs underlines the unique adaptations arthropods have developed, but as a group, they are not typically defined by the presence of lungs.