Protostome - Mouth forms first

Deuterostomes - Mouth forms second

1. include starfsih, sharks, frogs, turtles, birds and mamls
2. Triploblastic coelomates (3 layer - body cavity)
3. Three phyla:
   1. Echinodermata (starfish, sea urchins)
   2. Hemichordata (acorn worms)
   3. Chordata (fishes, tetrapods)

Phylum Echinodermata

• 7,000 described spp. of "spiny-skinned" animals, including sea lilies, starfish, and brittle stars, sea cucumbers
• Three Classes: Crinoidea, ASteroida, Ophiuroidea

Phylum Chordata

body plan: a notochord, pharyngeal slits, dorsal hollow nerve cord, and postanal tail (only found in the human embryo)

Subphylum Urochordata

Marine tunicates, sea squirts, etc.

• Have traits of chordates in larval form
• Enclosed in a non-living tunic (big bag)

marine tunicate

Subphylum Cephalochordata

sea lanceletes: resemeble a small lance or willow leaf

nerve cords and notochords persists along entire length of animal