BIOL-UA 12 Lecture 7: Lecture 7 _Animal Diversity I_
18 Mar 2016
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Document Summary
The history of animals spans > . 05 billion years. The common ancestor of animals lived 675-800 million years ago. Great diversity of living species (1. 3 million) and an even greater diversity of extinct ones. Multicellular true tissues (including nervous and muscle tissues lack cell walls structural proteins such as collagen. Reproducing: most animals reproduce sexually diploid stage usually dominates the life cycle, several animals are hermaphrodites s(sperm and egg) 95% of known animal species are invertebrates = animals that lack a backbone. Collar (choano) with a stalk, single cell, and have a flagella. Large species that are sedentary suspicions feeders, with numerous pores. Sponges lack true tissue and organs (not animals) but have specialized type cells. Flagellum generates a water current, the collar traps good particles, and the collar cell ingests these foods through phagocytosis where an amoebocyte carries nutrients to other cells.
