BIOL412 Chapter Notes - Chapter 44: Endodermis, Agnatha, Swim Bladder
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44. 1 a tree of life for more than a million animal species. The organisms most closely related to animals are choanoflagellates (type of protist). Does not mean that multicellular = animal, as plants and fungi are also multicellular. What makes animals different from plants is that animals are heterotrophs. This means they cannot create energy themselves, and instead rely on consuming plants or other animals as a source of carbon and energy. What makes animals different from fungi (which are also heterotrophs) is that animals have a specific pattern of early embryological development. That"s a character not found in fungi or other multicellular groups. The fundamental mechanism by which biological diversity increases is speciation (= the divergence of two populations from a common ancestor). Speciation creates a tree-like pattern of relatedness, also called a phylogenetic tree. The branches of a phylogenetic tree do not say much about time, but rather the complexity of that organism.