- Plasmogamy involves the fusion of cytoplasm between two parent fungi without nuclear fusion, forming a secondary mycelium with one nucleus from each parent. Karyogamy involves nuclear fusion and produces genetic variation through somatic diploids. - Animal cells lack cell walls and have structural proteins like collagen to hold their multicellular bodies together. Most animals reproduce sexually through fertilization and have a diploid stage dominating their life cycle. - Animal development proceeds through cleavage, formation of a blastula and gastrula, and then organogenesis from the three germ layers. Their multicellular origin can be traced to colonial protistan ancestors.