Origin of metazoa | theories of origin of metazoa easy way

Origin of metazoa. Hackel's theory simple and easy way #originofmetazoa ....
origin of metazoa
The theories are devided into three groups
i)
Colonial theory
Butchli’s theory
Lankster’s theory
Haeckel’s theory
ii)
Syncytial theory
iii)
Polyphyletic theory
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