Chapter 32- Overview of Animal Diversity Flashcards
What are the 5 key transitions in animal evolution?
- ) Tissues
- ) Symmetry
- ) Body Cavity
- ) Development
- ) Segmentation
Define Tissues
Closesly associated, similar or identical cells that work together to perform one or more functions
Define Organs
Discrete body part composed of several tissue types that performs one or more functions
Organ system?
Several organs that work together to perform one or more functions (circulatory system)
What are the two types of animals as defined by tissues
Parazoa-sponges, lack defined tissues and organs
Eumatozoa-all other animals
What are the two main types of symmetry in animals?
Radial symmetry
Bilateral symmetry
What is Radial Symmetry
Body parts arranged around central axis
-Can be bisected into two equal halve in any 2d plane
Bilateral Symmetry
Body has right and left halves that are mirror images; adaptation for motile life
What are the 2 advantages bilateral animals have over the radially symmetrical ones
Cephalization
Greater mobility
What is cephalization
evolution of a definite brain area; contains most sensory apparatus
What is the ectoderm
The outer germ layer-body coverings and nervous system
What is the mesoderm
The middle germ layer; skeleton and muscles and many internal organs
What is the endoderm
the inner germ layer; The digestive organs and intestines
What is the order of germ layers during embryonic development
Ectoderm (outer)
Mesoderm (middle)
Endoderm (inner)
What is the coelem
The body cavity; space between the endoderm and mesoderm
What are the 3 basic kinds of body plans
Acoelomates
Pseudocoelomates
Coelomates
What are acoelomates
no body cavity
What are pseudocoelomates
body cavity between mesoderm and endoderm
What are coelomates
Body cavity entirely within the mesoderm
What is an Open Circulatory system
blood passes from vessels into sinuses, mixes with body fluids, and reenters the vessels
What is a closed circulatory system
blood moves continuously through vessels that are separated from body fluids
What is the Blastula
Mitotic cell divisions of the egg form a hollow ball of cells: the blastula
What is the Blastopore
The blastula indents to form a 2 layer thick ball with an opening to the outside
What is the archenteron
formed from the blastula, it is a primitive digestive tract
What are Protostomes
They develop the mouth first from or near the blastopore
-anus develops either from blastopore or another region of embryo
What are Deuterostomes
develop the anus first form the blastopore
-mouth develops later from another region of the embryo
Cleavage pattern of embryological features
Protostomes= spiral cleavage
Deuterostomes=radial cleavage
Development fate of cells in bilaterians
Protostomes: determinate development
Deuterostomes: indeterminate development
Origination of Coelom in Bilaterians
Protostomes= Forms simply and directly from the mesoderm
deuterostomes=forms indirectly from the archenteron
Which (protostome or deuterostomes) are more evolutionary recent?
Deuterostomes; evolved from protostomes
What are the 2 advantage of segmentation
- ) allows redundant organ system in adults such as occurs in the annelids
- ) allows for more efficient and flexible movement because each segment can move independently
