Phylum Platyhelminthes
Worm Prevalence Speculation: worm form maybe the ___ to house a ___
Simplest way; complete digestive system
Complete digestive system: ___ at one end and ___ at the other
Mouth; anus
A complete digestive system provides ___
Huge benefits
Worm Prevalence Speculation: worm body has much ___ in contact w ___
Surface area; substrate
Surface area in contact w substrate makes ___ and ___ easy
Swimming; crawling
Phylum Platyhelminthes:
Flatworms
Feature 1: all are ___
Acoelomate
Acoelomate: ___ w no ___ or ___
Solid; body cavity; coelom
Coelom
Body cavity
___: a loose net like aggregation of ___
Parenchyma; irregularly shaped cells
Feature 2: show some ___ including brain like cluster of ___ at 1 end
Cephalization; ganglia
Ganglion
A cluster of neurons
Feature 3: ___ flattened
Dorsoventrally
Feature 4: if a ___ exists ___ is the only opening
Digestive system; mouth
Feature 5: lack ___ and ___ systems
Respiratory; circulatory
Feature 6: lack a ___ – body is ___
Skeleton; entirely soft
Feature 7: ___ – body derived from ___ germ layers
Triploblastic; three
Recall: all cnidarians are ___
Diploblastic