BIOL 111 Lecture Notes - Lecture 11: Flatworm, Invagination, Skeleton

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Rajinder Dhindsa

Document Summary

Biol 111-lecture 11-embryonic development and symmetry, cnidarians and. Platyhelminthes: embryonic development, zygote multicellular organism, diploid cell resulting from union of two haploid gametes, 1st cell of next generation. Embryo young animal of plant while it is still contained within a protective structure: two major processes curing embryonic development. Cleavage process forming many cells from one cell. Gastrulation in-folding, invagination, process forming embryonic tissue layers. --gastrula layers of embryonic cells are formed=germ layers (ectoderm epidermis, nervous system; endoderm lining of respiratory and digestive system; mesoderm most internal organs & muscles, skeletal system, heart, stomach; archenteron digestive space, gut cavity blastr opore mouth & anus) Mesoglea, between ectoderm and endoderm (collagen and proteoglycans) Sexual reproduction: simple nervous system nerve net sensory information from any direction little to no integration or processing of signals provide direct lines of communication between sensors and effectors (muscles, diversity. -polyp dominant, alternate between polyp and medusa e. g. hydra. Portuguese man-of-war (colonial polyps specialized for different functions)