BSC 1011L 6, 7 & 8

• What are three types of body symmetry?

  asymmetry, radial symmetry, bilateral symmetry
• asymmetry


  having no symmetry
• radial symmetry


  symmetry around a central axis

  
• bilateral symmetry


  symmetry with right-left mirror images

  
• cephalization


  formation of a head
• anterior


  head end of an animal
• posterior


  away from the head end, or rear end of an animal
• dorsal


  top or back side
• ventral


  front or belly side
• gastrulation


  Stage of embryonic development; reorganization of the hollow ball of cells (blastula) into germ layers; has archenteron and blastopore

  
• germ layers

  cell layers of the embryo- the ectoderm, mesoderm and endoderm

  
• ectoderm


  outermost germ layer (develop into skin and nervous system)

  
• mesoderm


  middle layer (develop into circulatory and reproductive systems, muscles, and bones

  
• endoderm


  innermost germ layer (develops into lining of digestive and respiratory tracts, as well as liver, pancreas and other glands

  
• blastopore


  During gastrulation: the pore or opening formed in the hollow blastula

  
• protostome


  Organisms in which the blastopore becomes the mouth. "mouth first"

  
• deuterostome


  Organisms in which the blastopore becomes the anus. "mouth second"

  
• diploblastic


  animals having two cell layers (no mesoderm)

  
• triploblastic


  animals having three cell layers (endoderm, mesoderm and ectoderm)

  
• coelom


  A second body cavity that forms between the germ layers. Organs are suspended and protected in this cavity.

  
• acoelomate


  not having a coelom or enclosed body cavity

  
• pseudocoelomate


  having a fluid filled space, but it is not a true cavity formed from the mesoderm

  
• coelomate


  a true body cavity formed from the mesoderm, as in the earthworm

  
• What is the one group that lacks true tissues?

  Phylum Porifera
• Collagen


  fibers that support animal cells. Only found in animals
• Porifera


  sponges. Oldest lineage of animals

  
• Eumetazoa


  "true animals". Clade that consists of all animals except sponges (Porifera)
• Oldest lineages within Eumetazoa

  Cnidaria (and Ctenophora).
• Bilateria


  All other animals except Cnidaria and Porifera

  
• Sponges (Phylum Porifera)


  Single germ layer, Acoelomate, No mouth or anus, No true tissues, Asymmetrical.

  
• Spongocoel


  interior cavity of the sponge. Note the repeated use of coel for interior cavity (coelom, blastocoel)

  
• Choanocytes


  flagellated cells that line the spongocoel and draw water through the sponge by the movement of the flagella

  
• Skeleton of a sponge

  made up of spongin fibers and spicules
• spicules


  part of the skeleton of the sponge, made up of calcium carbonate or silica (glass).
• Sequential hermaphrodites


  when individuals can function as a male and a female, but at different times
• glass sponge

  
• bath sponge

  
• Phylum Cnidaria

  Two germ layers, Acoelomate, Only one opening (mouth), Have true tissues, Radial symmetry

  
• Medusozoans


  Cnidarians- include Hydrozoa, jellies, and box jellies
• Medusa


  free moving form of medusozoans