Animal Body Plans, Taxonomy and Phylogeny Flashcards
What did early zoologists use to describe relationships between animals?
Body Plans
- symmetry
- segmentation
- size and shape
Are body plans useful for understanding relationships between animals?
No. It’s useful for for describing differences but not for understanding relationships because of convergent evolution.
What are the types of symmetry?
Radial Symmetry
-Symmetry around a central point
Bilateral Symmetry
-Symmetry accross the sagittal plane
Asymmetry
-No planes of symmetry
What characteristics are associated with bilateral symmetry?
Directional movement
Cephalization
-sense organs and mouth usually at head
What is segmentation?
repetition of structures along the longitudinal axis of body
-result from linear series of mesodermic somites
What is the purpose of body cavities?
allow for
- greater separation of function
- localization of internal organs
- hydrostatic skeleton in place of endo/exo
What is modularity?
Increasing body size by adding new units
-adding modules that are genetically identical but not morphologically identical
What is coloniality?
Increasing body size by adding ramets
-adding modules that are genetically identical and morphologically identical
What are different constraints of body plans?
Hydrostatic skeletons and Exoskeletons cause all animals with that feature to look alike
Give examples of constrained body plans.
Highly Constrained
-Annelida - Hydrostatic skeleton under pressure
Moderately Constrained
-Arthropoda - exoskeleton limits size
Unconstrained
-Mollusca, Chordates - grow large
How do surface area/volume ratio interact?
Size
-Large animals have less surface area relative to their volume than smaller animals of same shape
Shape
-Two organisms with the same volumes can have different ratios depending on shape
How do size and shape influence endotherms?
Endotherms (Produce heat internally)
- Volume: heat generating
- Surface area: heat losing
- Result: minimize surface area/volume ratio w/ large size
How do size and shape influence ectotherms?
Ectotherms (Capture heat)
- Volume: heat usage
- Surface area: heat capturing
- Result: maximize surface area/volume ratio w/ small size and snake like shapes
What are the pros and cons of having a large size body plan?
PROS
- buffer against small environmental fluctuations
- provide greater protection against predation
- enhance offensive tactics
CONS
-sudden large environmental changes will kill off the large animals first (require large amounts of energy)
What is taxonomy?
systematic ordering and naming of organisms
