Chapter 32: Animal Diversity
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What are 3 general features of all animals?
- No cell walls
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 _____
- longitudinal plane through the central axis divides the animal into two halves that are mirror images of each other.
- Examples: members of phylum Cnideria
- 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 or False: Specialization is irreversible in all animals.
False! All animals, EXCEPT sponges.
List the 4 steps of early embryonic development:
- Blastula formation
- Gastrula formation
succession of mitotic cell divisions without cell growth between the divisions
hollow ball of cells produced by cleavage; cavity inside is the blastocoel.
formed from the blastula when one end of the embryo folds inward, expands, and fills the blasocoel.
- 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:
The endoderm gives rise to:
- digestive system, including intestines
- organs like the liver
- lungs of vertebrates
Animals that have all three germ layers are ____.
- Also members of the bilateria
Cnidarians have how many germ layers?
- Only two germ layers
_____ are diploblastic, meaning they have no organs.
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
- Body cavity develops entirely within the mesoderm
- Example: annelids, humans
- No body cavity between digestive tract and muscle layer.
- Example: flatworms
- 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?
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.
Bilaterians have 2 main types of development:
- 1. Protostome
- 2. Deuterostome
- "First mouth"
- Mouth develops from the blastopore
- Example: flatworms, nematodes, mollusks, annelids, arthropods
- "second mouth"
- anus develops from the blastopore
- Examples: echinoderms (starfish, sea urchins) and chordaes (humans, animals with backbone)
Chordates and echinoderms are (protostomes/deuterostomes).
Opening into the archenteron
Name the two types of cleavage patterns:
- Spiral cleavage
- Radial cleavage
- New later of cells, nestles into the space between the older cells
- Examples: annelids, mollusks, nemerteans, and other protosomes.
- pairs of new cells are positioned directly above the older cells
- Example: All deuterostomes
Protostomes have (determinate/indeterminate) development.
Deuterostomes have (determinate/indeterminate) development.
- the type of tissue that each embryonic cell will form is determined early
Each cell remains totipotent and each cell's fate is not determined for several cleavages.
What are the advantages of segmentation?
- Efficient and flexible movement
- Redundant organ systems
There are _____ phyla based on shared characteristics. All animals share a common ancestor.
includes the sponges that DO NOT have embryonic germ layers or differentiated cells that form tissues.
- includes animals that have embryonic germ layers and differentiated cells that form tissues.
- Most animals
What has helped reveal evolutionary relationships?
Morphology and molecule based phylogenies agree on many major groupings.
- Sponges: monophyletic; shares common ancestor with other animals
- Cnidarians: evolved before bilaterally symmetrical animals
- Annelids and arthropods were thought to be closely-related based on segmentation, but the arthropods are now grouped with animals
____ evolved before bilaterally symmetrical animals
____ molt their cuticles at least once during their life.
Morphology-based phylogeny focused on the state of the ____.
The protostomes and deuterostomes differ in ______.
Embryology (mouth or anus development)
All acoelomates and pseudocoelomates are (deuterostomes/protostomes).
True or Falsue: All coelomates deuterostomes.
False. Some coelomates are protostomes (like earthworms) and some are deuterostomes (humans).
Protostomes consist of what two subgroups?
Spiralian animals grow by:
adding mass to the body and exhibit spiral cleavage
Ecdysozoans grow by:
- they grow by molting external skeletons.
- nematodes and arthropods
Annelids, mollusks, rotifers, platyhelminthine worms, ectoprocts, and brachiopods are _____
Lophotrochozoa, spiralian animals (subgroup of protosomes)
- Patterns of development indicate that echinoderms and chordates evolved from a common ancestor
Metazoans appear to have evolved from colonial _____.
The Eumentazoa most likely evolved from colonial _____.
_____ analysis may explain the Cambrian explosion.
Rapid diversification may be result of evolution of ______ genes.
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