BIOL 152 1st Edition Lecture 12 Outline of Last Lecture Animal Diversity Outline of Current Lecture The First Animals Animals most likely derived from a colonial flagellated protists like today s choanoflagellates Multicellular organisms have different specialized cells Unicellular organisms have group of cells that work toward a similar goal colonial these ancestors lived 1 2 billion years ago 800 million years ago Choanocytes are collar cells that absorb food similar colonial structures Precambrian animals The Ediacaran fossils document embryos and small soft bodied animals Sponges were the first fossil record cnidarians that began to appear latter during this period Geologic Time Scale These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute als m i An Land plants Fig 2610 Paleozoic Mesozoic Origin of solar CenosystemSingle celled andzoic Earth eukaryotes 4 Prokaryotes 1 2 3 Multicellular eukaryotes The Cambrian Explosion Occurred 542 million years ago At the beginning of the Paleozoic was the time period when most animal phyla and all major body plans appeared Paleozoic fishes dominated the marine environment insects and plants colonized land amphibians appeared then reptiles appeared on land Causes of Cambrian explosion predator prey relationship increase in oxygen hox gene complex arose Mesozoic coral reefs formed and provided new niches reptiles dominated the seas and land small nocturnal mammals appeared birds began to appear during this time Cenozoic was followed after mass extinction during this time period major radiation of flowering plants and insects appeared large mammalian herbivores and carnivores appeared Animal Characteristics 1 Heterotrophs have to consume food 2 Multicellular 3 No cell walls 4 Specialized cells only found in animals muscle and nerve 5 Most reproduce sexually 6 Diploid form dominated the life cycle 7 Regulatory genes hox genes Early developmental patterns Most animals reproduce sexually The zygote proceeds through several stages of mitotic divisions Cleavage Blastula Gastrula Current Lecture Animal Diversity
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