Multicellularity
Single-cell Ancestor
A flexible axis. Present in Embryo. Replaced by Vertebal Column.
Medusa(Upside-down bowl Shape):MotileSexual
Cell → Tissue → Organ → Organ System
Larvae: BilateralAdult: Radial
Radial Symmetry
Notochord
Sponge(Porifera)
Cnidarians
Arthropods
Tissues
Three Germ Layers
Planaria
Diploblastic:Ectoderm + EndodermMesoglea: connection
Coelom
Flat Worms(Platyhelminthes)
Echinoderms
Cephalization
Pharyngeal gill slit
Bilateral Symemetry
Roundworms (Nemarodes)
1. Bilateral and Coelomate2. Digestive system: A tube within a tube; Crop (嗉囊) + Gizzard (砂囊) + Intestine3. Closed circulatory4. Nephridia: Excrete Urea5. Hermaphrodite
Basic structure of nervous system
Annelida(Annelids)
Mouth + Anus
Tail beyond digestive tract
Special Structures
Dorsal Nerve Cord
Primitive: RadialComlex: Bilateral(Many Triploblastic)
Gastrovascular cavity
1. Acoelomates: Digestive Cavity (Flatworms)2. Pseudocoelomate: Not completely lined with mesoderm (Nemarodes)3. Coelomate: With real coelom
Pseudocoelom
DeuterostomeDevelopment
1. Bilateral2. No respiratory or circulatory systems (Sheer Diffusion)3. Parasitic
Body Shape
1. Bilateral2. Open circulatory; Blood flows in Hemocoels or Sinuses
1. No symmetry2. No nerve or muscles3. Sessile4. Fragmentation or sexual reproduction5. Most are Hermaphroditic (Male And Female... Like Pea Flowers)
Tail behind anus: Motor and Balance.Human's COCCYX BONE is from tail
Extra-cellular Digestion+Lysosomes
Chordates
Direct Exchange of substances;Waste product: NH3
Mollusca(Mollusks)
Polyp Form(Vase Shape):SessileBudding
Peristom + 肠腔
Protosome Development
