chapter 13: Animal Evolution Flashcards
Porifera- sponges
no true tissues –> show plasticity
cells can change their identities (most do)
cells are connected by an extracellular matrix of protein and skeletal elements of calcium carbonate or silica (spicules)
Ctenephora- comb jellies
Ctenes- fused cilia form paddles
two tissue layers with mesoglea gel in between muscles, nerves through gut
complex animals
Why is multicellularity so significant ?
it allows for division of labour between cells and thus the formation of tissues (differentiated cells grouping into tissues to complete different functions)
thus leading to internal organization
most animals are composed of epithelia cells (sheets of cells)
describe the significance (location/function/form) of the following
Cuboidal epithelium
Simple columnar epithelium
pseudostratified ciliated columnar epithelium
stratified squamous epithelium
simple squamous epithelium
*focus on the relationship of form to function
Describe key characteristics of Cnidaria and their significance
two true tissue layers –>
epidermis (outside): muscle cells, nerve cells, and cnidocytes on tentacles (prey imobilization via toxins in the cells)
gastrodermis: muscle cells and digestive cells
radial symmetry–> no directional movement, no intentional movement (“wafting” movement)
gastrovascular cavity (sac with central digestive compartment-single opening functions as mouth and anus)–>
two examples of cnidaria
sea anemone and crystal jellyfish
What is bilateria and why is it significant?
most animals are bilateria (have bilateral symmetry) and three tissue layers
Bilateral symmetry: anterior/posterior; dorsal/ventral; right and left sides
organisms can partake in intentional directional movement. This is significant for prey hunting and predator avoidance/ survival.
Triploblastic: Three tissue layers: ectoderm, mesoderm (coelum), endoderm
coelum- body cavity (surrounds and contains the digestive tract “protection”)
organisms now can have complex systems, especially a digestive tract
Why is bilateral symmetry so significant?
why is triptoblasticity so significant?
allows for the formation of mesoderm layer/ coelum
internal organs are suspended and protected, large organs can develop, the digestive tract is independent of body movement therefore it does not move along with the movement of the body. there is cushioned protection
while previously no coelum movement was also minimal however once you get a coelum movement can become more intentional and sporadic?
describe the characteristics of a lophotrochozoan
locophore or trochopore at some stage in their life cycle
spiral cleavage in embryonic development
