1. Sea urchin
2. Sand dollar
3. Earthworm
4. Ichthyophis
Earthworm
1. Haemocoel
2. Neurocoel
3. Pseudocoelom
4. True coelom
True coelom
1. Sycon
2. Sepia
3. Nereis
4. Euglena
Sycon
1. Placoid scale
2. Ventral mouth
3. Ctenoid scale and ventral mouth
4. Placoid scale and ventral mouth
Placoid scale and ventral mouth
1. Seven cervical vertebrae
2. Seven cranial nerves
3. Fourteen cervical vertebrae
4. Single ventricular chamber
Seven cervical vertebrae
1. Pinctada roding
2. Pinctada margaritifera
3. Placuna blacenta
4. Pinctada maxima
Pinctada margaritifera
1. Cyclostomata
2. Osteichthyes
3. Chondrichtyles
4. Amphibian
Chondrichtyles
1. Pavo
2. Struthio
3. Columba
4. Testudo
Testudo
1. Aves
2. Reptiles
3. Amphibians
4. Fishes
Aves
1. Sea horse
2. Sea hare
3. Sea pen
4. Sea cucumber
Sea pen