Name 3 things that some, but not all animals are capable of...
The ability to actively move
Sexual reproduction
Specialized tissues
What does it mean for an animal to have specialized tissue?
Muscles and nerve cells are central to the animal's lifestyle
What are the 5 key innovations in animal evolution?
1. Symmetry
2. Tissues that allow for specialized structures/functions
3. Body cavity
4. Various patterns of embryonic development
5. Segmentation or repeated body units
Most animals exhibit ___ or ___ symmetry.
Radial or bilateral
Shape: Sponges are _____
Asymmetrical
Radial symmetry:
longitudinal plane through the central axis divides the animal into two halves that are mirror images of each other.
Examples: members of phylum Cnideria
Bilateral Symmetry:
Body has right and left halves that are mirror images of each other
Example: Most animals that are not sponges or Cnidarians
What are some advantages of bilateral symmetry?
Move in a consistent direction with head end leading
Associated with brain, sensory structures such as eyes and ears (cephalization)
Give an example of an animal type with radial symmetry:
members of the phylum Cnidaria
Give an example of an animal type with bilateral symmetry:
Most animal that are not a sponge or cnidarian
What is cephalization?
Centralization of neural and sensory organs in the head or anterior region of the animal
The evolution of tissues allowed for _____ and ___.
Specialized structures and functions
Zygotes are _____. They can give rise to any and all cells in the animals body.
Totipotent--all powerful, cell fate not yet determined
True or false: Cells specialize during embryonic development
true
True or False: Specialization is irreversible in all animals.
False! All animals, EXCEPT sponges.
List the 4 steps of early embryonic development:
Cleavage
Blastula formation
Gastrula formation
Archenteron
Cleavage:
succession of mitotic cell divisions without cell growth between the divisions
Blastula
hollow ball of cells produced by cleavage; cavity inside is the blastocoel.
Coel means what?
Cavity
Gastrula:
formed from the blastula when one end of the embryo folds inward, expands, and fills the blasocoel.
Archenteron:
pouch inside the gastrula
opens to the outside via the blastopore
What made possible the development of advanced organ systems?
A body cavity
What are the 3 germ layers?
1. Ectoderm (outer layer)
2. Mesoderm (middle layer)
3. Endoderm (inner layer)
The ectoderm layer gives rise to:
nervous system
outer covering of the body
The mesoderm gives rise to:
Skeleton
Muscles
The endoderm gives rise to:
digestive system, including intestines
organs like the liver
lungs of vertebrates
Animals that have all three germ layers are ____.
triploblastic.
Also members of the bilateria
Cnidarians have how many germ layers?
Only two germ layers
Ectoderm
Endoderm
_____ are diploblastic, meaning they have no organs.
Cnidarians
True or false: Sponges have some tissues but no organs
False! Sponges do not have any tissues or organs!
Name the 3 body plans for bilaterally symmetrical animals (CAP):
1. Coelomate
2. Acoelomate
3. Pseudocoelomate
Coelomate:
Body cavity develops entirely within the mesoderm
Example: annelids, humans
Acoelomate
No body cavity between digestive tract and muscle layer.
Example: flatworms
Pseudocoelomate
Have body cavity that develops between mesoderm and endoderm
Example: Roundworms
Which body plan for bilaterally symmetrical animals contains those with a body cavity between the medoderm and endoderm?
Pseudocoelomate
The circulatory system functions to carry ______ to tissues and removes ________, by diffusion between the circulatory fluid and other cells in the body.
nutrients and oxygen
wastes, including carbon dioxide
Open circulatory system:
blood passes from vessels into sinuses, mixes with body fluid that bathes the cells or tissues, and then re-enters vessels in another location.
Closed circulatory system:
Blood is entirely confined to vessels and is physically separated from other body fluids.
