: Categorization into artificial and natural systems based on evolutionary relationships. Body Bauplans
invertebrate zoology lecture notes and presentations (PPT) typically review the of animals without a backbone, which comprise approximately 97% of all animal species . Core Review Concepts
: Most are mobile at some point in their life cycle, though some (like sponges) are sessile as adults. Support Structures : Many use exoskeletons arthropods hydrostatic skeletons cnidarians , annelids) for protection and structure Classification Criteria
