PROTOSOME/DEUTROSOME

Animals

Multicellular, heterotrophic, lack cell walls

Porifera

No true tissues, asymmetrical, choanocytes, spicules

Ctenophora

Biradial symmetry, comb rows (ctenes), diploblastic

Cnidaria

Radial symmetry, diploblastic, cnidocytes, gastrovascular cavity

Bilateria

Bilateral symmetry, triploblastic development, cephalization

Protostomia

Mouth forms first (classic), spiral cleavage, mesoderm splits

Lophotrochozoa

Trochophore larva OR lophophore OR spiral cleavage

Rotifera

Pseudocoelom, ciliated corona for feeding, complete digestive tract

Platyhelminthes

Acoelomate, flattened body, incomplete digestive tract

Annelida

True coelom, segmentation, chaetae (bristles)

Mollusca

Mantle, muscular foot, visceral mass, often radula

Ecdysozoa

Growth by molting (ecdysis), cuticle or exoskeleton

Nematoda

Pseudocoelom, thick cuticle, longitudinal muscles only, molting

Tardigrada

Molting, segmented body, cryptobiosis ability

Onychophora

Velvet worms, lobopod legs, molting, transitional to arthropods

Arthropoda

Segmented body, jointed appendages, chitinous exoskeleton

Deuterostomia

Anus forms first, radial cleavage, mesoderm outpocketing

Echinodermata

Pentaradial adults, water vascular system, tube feet, calcareous endoskeleton

Chordata

Notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail (at some life stage)

Cephalochordata (Lancelets)

All four chordate traits retained as adults, no vertebrae, no cranium

Urochordata (Tunicates)

Larvae have chordate traits, adults lose notochord and tail, tunic present, sessile adults

Vertebrata

Vertebral column, cranium, neural crest cells, complex brain

Myxinoidea (Hagfishes)

Cranium present, no vertebrae, no jaws, slime production

Petromyzontida (Lampreys)

Cranium, rudimentary vertebrae, no jaws, parasitic lifestyle

Gnathostomata

Jaws, paired appendages, increased feeding efficiency

Chondrichthyes (sharks, rays, and skates)

Cartilaginous skeleton, jaws, paired fins, no swim bladder

Actinopterygii

Bony skeleton, ray-finned appendages, swim bladder

Sarcopterygii

Lobed fins with internal bones, lungs in some groups

Actinistia (Coelacanths)

Lobed fins, fleshy appendages, skull hinge

Dipnoi (Lungfishes)

Lobed fins, lungs, air breathing, closest living relatives of tetrapods

Tetrapoda

Four limbs with digits, neck, strengthened vertebral column

Amphibia

Moist skin, eggs laid in water, metamorphosis, cutaneous respiration

Anura (Frogs & Toads)

No adult tail, long hind limbs for jumping, external fertilization common

Urodela (Salamanders)

Tail retained as adults, elongated body, limbs present

Gymnophiona (Caecilians)

Limbless, burrowing, reduced eyes

Amniota

Amniotic egg, internal fertilization, keratinized skin

Mammalia

Hair, mammary glands, three middle ear bones, endothermy

Reptilia

Keratinized scales, ectothermy, amniotic egg

Lepidosauria (lizards, snakes)

Overlapping scales, movable quadrate bone

Testudinia (turtles)

Shell composed of ribs and vertebrae, toothless beak

Crocodilia

Four-chambered heart, parental care, secondary palate

Aves

Feathers, hollow bones, endothermy, wings