Pistolpete007:
Platyhelminthes include trematodes, cestodes, flatworms, flukes, tapeworms, etc. They have bilateral body symmetry no respiratory, circulatory, or coeloms. Their digestive systems are either incomplete or absent, they use flame cells or protonephridia for excretion. Nerve rings or long nerve cords make up their nervous system. They have all 3 germ layers: Epi, Meso and Endoderm and they reproduce sexually by internal fertilzation (hermaphrodites).
Annelids includes Earthworms, lumbricoids, etc. They have bilateral body symmetry, a complete digestive system, no respiratory system, a closed and complete circulatory system. This too has all 3 germ layers and also reproduces sexually-internal fertilization (herma.). They use true nephridia aka metanephridia for excretion.
Nematodes are like roundworms (ascarius, etc.) Similar to annelids in many ways but their sexes are separate and they use a simple way of excretion.
