Question

The presence or absence of mandibles can be used to distinguish between

• A. Insects and centipedes
• B. Insects and crustaceans
• C. Insects and millipedes
• D. Insects and spiders

Answer 1

The correct option is D Insects and spiders

• Insect mandibles are a pair of appendages near the insect's mouth, and the most anterior of the three pairs of oral appendages (the labrum is more anterior, but is a single fused structure). Their function is typically to grasp, crush, or cut the insect's food, or to defend against predators or rivals.
• Insect mandibles, which appear to be evolutionarily derived from legs, move in the horizontal plane unlike those of vertebrates, which appear to be derived from gill arches and move vertically.
• Spiders are different from insects in several features, especially in the absence of mandibles.