Practice question

Myriapoda includes Chilopoda centipedes, Diplopoda millipedes, Pauropoda and Symphyla, characterized by elongated homonomous trunk with numerous segments each bearing legs and head with single pair of antennae, not two as in crustaceans. Antennae moniliform or filiform serve olfaction and tactile sensation via sensory setae and cone sensilla. Second antennal pair lost during atelocerate evolution reflecting head segment fusion and mandibular specialization. Three pairs of antennae absent in arthropods. Single antennal pair thus distinguishes myriapods and hexapods from crustaceans with two pairs and chelicerates lacking antennae, providing clear subphylum synapomorphy used in identification keys.