BIO SCI 94 Lecture Notes - Lecture 6: Cephalization, Cephalopod, Cnidaria

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Nancy Burley

Document Summary

Increase in free oxygen (cyanobacteria; eukaryotic algae: 2. As some organisms got larger, new biotic niches created: 3. Previously soft-bodied animals, probably not hunters increased body size increased skeletalization: 4. Homeotic genes: specifies axis and segment identity (location) within embryo to develop certain structure this gene arose once. Paedomorphosis: retention in adults of juvenile features of ancestors, occurs by stopping development sooner or slowing rate of development. Mesoderm: muscle, circulatory system, bone, organs, cephalization. Neural tissue, sensory regions, etc: central nervous system. Orient and move in one direction: coelom. A fluid-filled body cavity completely lined by mesoderm. Coelomates: enclosed body cavity completely lined with mesoderm. Pseudocoelomates: an enclosed body cavity partially lined with mesoderm, hydrostatic skeleton. System of body support with body wall surrounding fluid under compression: protostomes looks like worms, 22 phyla, protostomes = first mouth = mouth, deuerostomes = second mouth = anus, 1st radiation: lophotrochozoa. Named for ciliated structures for feeding: phylum platyhelminthes, flatworms.