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Phyla: Chordata, Echinodermata, Arthropoda, Pentastomida, Nematomorpha, Nematoda, Mollusca, Annelida, Nemertea, Platyhelminthes, Ctenophora, Cnidaria, Porifera, Choanoflagellata
Organization: Triploblasts, Deuterostomes, Ecdysozoans, Lophotrochozoans, Protostomes, Metazoa, Diploblasts

Chordata: Animals with notochord at some life stage
Vertebrata: Chordates with vertebrae and cranium
Gnathostomata: Vertebrates with jaws
Osteichthyes: Bony fishes + tetrapods
Tetrapoda: Four-limbed vertebrates
Amniota: Tetrapods with specialized embryonic membranes
Protochordata: Includes Agnatha, Cephalochordata, Cyclostomata, and Urochordata
Chondrichthyes: Sharks, rays, chimaeras
Actinopterygii: Ray-finned fishes
Tetrapod classes: Amphibia, Mammalia, Reptilia (Lepidosauria, Crocodilia, Testudines), Aves

Notochord: Flexible structure, replaced by vertebrae in vertebrates
Dorsal Tubular Nerve Cord: Hollow, protects brain and spinal cord
Pharyngeal Pouches and Slits: Filter-feeding, gill evolution in vertebrates, Eustachian tubes in humans
Endostyle or Thyroid Gland: Secretes mucus for feeding, homologous to thyroid gland
Post-anal Tail: Used for swimming, modified in different species

Urochordata (Tunicates): Marine, free-swimming larvae, sessile adults, filter feeding
Cephalochordata (Lancelets): Live on sandy bottoms, retain all chordate hallmarks as adults
Vertebrata: Endoskeleton, specialized organ systems

Cyclostomata (Jawless Fishes): Lack vertebrae, with a cartilaginous skeleton, includes hagfishes and lampreys
- Hagfishes: Marine, eyeless, produce slime
- Lampreys: Freshwater larvae, parasitic adults
Chondrichthyes (Cartilaginous Fishes): Jaws, paired appendages, etc.
- Examples: Sharks and rays, streamlined bodies, specialized sensory systems