Plasmogamy- the cytoplasm of two parent mycelia fuse together without the fusion of nuclei, as occurs in higher terrestrial fungi. After plasmogamy occurs, the secondary mycelium forms. The secondary mycelium consists of dikaryotic cells, one nucleus from each of the parent mycelia.
Karyogamy- In fungi that lack sexual cycles , it is an important source of genetic variation through the formation of somatic diploids .
Animals are multicellular, heterotrophic eukaryotes. In contrast to the autotrophic nutrition of plants and algae, animals must take into their bodies preformed organic molecules; they cannot construct them from inorganic chemicals. Most animals do this by ingestion---eating other organisms or organic material that is decomposing.
Animal cells lack the cell walls that provide strong support in the bodies of plants and fungi. The multicellular bodies of animals are held together by structural proteins, the most abundant being collagen.
Animal symmetry is of three types: irregular (asymmetry), radial and bilateral. Irregular symmetry is the most primitive type of symmetry followed by radial, and the most advanced type which is the bilateral symmetry.