BIO 182 Lecture Notes - Lecture 20: Homeostasis, Motility, Coelom
Document Summary
Burst in animal diversity during cambrian era: 15 million years long, possibly initiated by complex predator-prey relationships. Define animals: no cell walls, eukaryotes, extensive extracellular material, get carbon from other organisms, get energy from ingestion, motility at some point in their life. Growth and development: form and function, specialize cells by expressing different parts of the dna, reproduction. Can"t reproduce until development is complete since it"s so costly. Evolution: from choanoflagelates, more complex, sense and respond to environment. Muscle cells (except sponges: internal regulation. Key features: symmetry radial or bilateral, structure of the body cavities. Coelomate organs lined with mesoderm tissue (muscles: segmentation. Allows complex alterations of the body shape. Deuterostome: radial cleavage, mouth opposite of blastopore, coelom from mesodermal pockets form body cavities, most bilaterally symmetric animals are deuterostomes, triploblastic. Amphibians: first land animals, need water for reproduction, become terrestrial as adults. Tetrapods: amphibians, mammals, and reptiles, four feet, foot print discovery. Water to land barriers: breathe, reproduction.
