Branch of ZOOLOGY or Animal Biology - the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems.. It also includes Anthrozoology, Arachnology, Archaeozoology, Bionics, Cetology, Embryology, Ethology, Helminthology, Herpetology, Histology, Ichthyology, Malacology, Mammalogy, Morphology, Nematology, Ornithology, Palaeozoology, Pathology, Primatology, Protozoology, Taxonomy, Zoogeography, Zoography, Zoometry, Zootomy, etc.).