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Animal Evolution. Precambrium Sea Multicellular Competition. Characteristics of animals. Animals are multicellular heterotrophic eukaryotes Ingestion to make inorganic chemicals Animal cells lack cell walls and are held together by proteins (collagen) Nervous Tissue and Muscle Tissue
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Animal Evolution • Precambrium Sea • Multicellular • Competition
Characteristics of animals • Animals are multicellular heterotrophic eukaryotes • Ingestion to make inorganic chemicals • Animal cells lack cell walls and are held together by proteins (collagen) • Nervous Tissue and Muscle Tissue • Reproduce sexually with the diploid stage being dominant
Early Embryonic Development Cleavage: mitotic division Multiple cells combine Blastula: hollow ball of cells Hollow portion called Blastocoel Embyronic Layers Form. Endoderm and Ectoderm
Traditional “Body Plans” • Major characteristics, embryonic development • Major branches called Grade 1. Parazoa-Eumetazoa: Formation of Tissues 2. Radiata-Bilateria: 3. Acoelomate-Pseudocoelomate-Coelomate 4. Protostome-Deuterostome:
Radiata-Bilateria Dichotomy • Bilateralism forms: Dorsal, Ventral, Anterior, Posterior • Cephalization: adaptation for movement. • Germ Layers: various layers of cells in development. • Ectoderm: gives rise to outer covering, CNS • Endoderm: innermost layer, digestive tube • Mesoderm: b/w other two layers, muscle and other organs • Diploblastic: two germ layers (radiata) • Triploblastic: Three germ layers (bilateria)
Protostome-Deuterostome Dichotomy Protostome: mollusks, annelida, arthropoda Deuterostomes: Echinodermata, Chordata • Cleavage: division of cells, • Spiral Cleavage: Protostomes, Early developmental fate, • Radial Cleavage: Deuterostomes, indeterminate cleavage • Coelom Formation: Blastophore Fate: Protostome: blastophore forms mouth Deuterostome: blastophore forms anus