Chapter 32 Flashcards
Asymmetry
No organization or symmetry
Radial symmetry
Any division through central axis yields mirror image
Bilateral symmetry
Only one division straight through middle yields an L/R image
Cephalization
“Head”, sensory organs concentrated at anterior end
Ectoderm
Germ layer covering surface of embryo (gives rise to nervous system, integumentary system)
Endoderm
Innermost germ layer (gives rise to digestive, respiratory, circulatory systems)
Mesoderm
In between ectoderm and endoderm (gives rise to muscular, skeletal system, & internal organs)
No tissue =?
No organization
Diploblastic
2 layers, ectoderm + endoderm
Triploblastic
3 layers, ectoderm + mesoderm + endoderm
Body cavity
space between outer body wall & digestive tract
Coelom
“Hollow”, body cavity
Coelomates
Animals w/ true body cavity
- Coelom derived from mesoderm only
- Lines both body wall and digestive tract
Pseudocoelomates
“False hollow”
- Coelom derived from mesoderm +endoderm
- Lines only body wall and not digestive tract
Acoelomate
No body cavity
Development
Zygote -> blastula -> gastrula -> embryo -> (larva -> metamorphosis ->) adult
Blastula
Hollow ball of cells
Gastrula
Tissue layer folds inward to form GI tract
Protostome
First opening is mouth
Deuterostome
First opening is anus
Larva
Sexually immature form (morphologically different from adult)
Metamorphosis
Developmental transformation into adult
Levels of tissue organization
Cellular -> tissue -> organ -> organ systems
Animal phylogeny
Need to identify by what they look like (morphological)
Choanoflagellates
Suspension feeder protista
Metazoans
Multicellular animals (ex. Porifera)
Porifera
Sponges (Ediacaron Period 550 mya)
Eumetozoa
Animals w/ true tissues
Protostomes
Platyhelminthes Nematoda Rotifera Mollusca Annelida Arthropoda
Ectoprocta
Brachiopoda
Echinodermata
Chordata
