The presence or absence of chelicerae distinguishes which groups among arthropods?

The presence or absence of chelicerae helps to distinguish between spiders and insects within the arthropod phylum. Chelicerae are specialized mouthparts found in the Chelicerata subphylum, which includes arachnids such as spiders, scorpions, and mites. These structures are typically adapted for feeding, such as piercing or grasping.

Insects, belonging to the subphylum Hexapoda, lack chelicerae altogether. Instead, they possess mandibles, which are different types of mouthparts used for various feeding strategies. This distinction makes it clear that the presence of chelicerae is a defining characteristic of spiders, while insects have a completely different structure. This anatomical feature is crucial in classifying these two significant groups of arthropods.