Two characteristics that arthropods possess that make them distinctive from annelids and chordates
1. Exoskeleton: Arthropods have a hard external skeleton made of chitin, which provides protection and support for their bodies. In contrast, annelids do not have a hard exoskeleton, and chordates have an internal skeleton made of bone or cartilage.
2. Jointed limbs: Arthropods have segmented bodies with jointed appendages that allow for a wide range of movement and specialized functions such as walking, swimming, and grasping. Annelids lack jointed limbs, and while chordates have limbs, they are not as highly specialized or diverse in their movements as those of arthropods.