Arthropod neurons and nervous system.

Arthropods are very diverse, come in many different forms with diverse adaptations, and through such diversity have populated all environmental niches on the planet. Almost 80% of the animals on planet Earth belong to this phylum. Despite their very diverse phenotypes they share fundamental similarities which were previously used to generate a phylogenetic tree. All arthropods have segmented bodies and possess jointed limbs at all or many of their body segments. An additional common feature of arthropods is their exoskeleton, made mainly of chitin and/or sclerotin.