BI256 Lecture Notes - Lecture 2: Archenteron, Blastocoel, Germ Layer
Document Summary
Lecture 2 animal architecture continued jan 6 /17. Intestine: salivary gland, liver, gall bladder, pancreases. More complex grades of metazoan organization permit and promote evolution of large body size. As body increases in size: surface area to volume ratios have important consequences for animal respiration, heat etc, surface area increases as the square of body length, sa=l2, volume increases as the cube of body length. Provides protection against predators and promotes offensive tactics. Cost of maintaining body temperature is less per gram of body weight than in small animals. Energy costs of moving a gram of body weight over a given distance less for larger animals. Series of progressive changes in an individual from its beginning to maturity. Begins when a fertilized egg divides mitotically. Specialization occurs as a hierarchy of developmental (cid:862)decisions(cid:863) Blastula cluster of cells (few hundred several thousand) created by the cleavage.
