Ch. 31 Biology
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External appendages do what?
- Allow better control of movement.
- May not be apparent externally
What are the body cavity functions?
- · Cushions suspended organs
- · Acts as a hydrostatic skeleton against which muscles can work (soft-bodied animals)
- mesoderm surrounds body cavity (coelom) and organs
- Ectoprocts, nemerteans, phoronids, brachiopods, annelids, mollusks and arthropods
mesoderm surrounds body cavity (pseudocoel) but not internal organs
- no fluid-filled body cavity
What are the three types of body cavities?
Where is the body cavity located?
between digestive tract and outer body wall
- Only 1 plane through midline divides animal into mirror-image halves.
Radial are and is?
- (cnidarians and ctenophores)
- Any plane along central axis divides animal into similar halves.
What are the three types of symmetry?
Asymmetrical, Radial, Bilateral
Animal Body Plans Vary in 4 features. What are the four features?
Symmetry, Body cavity, Body segmentation, External appendages
Triploblastic animals divided into 2 groups. What are those two groups?
protostomes and devitrosomes
Characteristics of animals are?
- · Muliticellular, heterotrophic eukaryotes
- · Ingest food and digest internally
- · Cells lack cell walls
- · Most have tissues and capable of movement
- · Most reproduce sexually (diploid stage usually dominates life cycle)
- · In most, a small flagellated sperm (n) fertilizes a larger, nonmotile egg (n) to form a zygote (2n)
- · Embryonic development regulated by Hox genes; includes cleavage and gastrulation
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