Ch 27: The Rise of Animal Diversity Flashcards
List the general characteristics of animals.
Multicellular; Heterotrophic; Cells lack cell walls and therefore can move during development and in the adult animal; Early development includes a blastula and typically a gastrula; Huge diversity
Describe how and why animal diversity has changed over time.
Animal diversity has been shaped by five mass extinctions followed by adaptive radiations; Most of the animal body plans seen today first evolved during the Cambrian explosion (period of land colonization)
List the characteristics associated with the major branch points on the phylogenetic tree of animal
Multicellularity - Poniferans
Multicellularity; Radial symmetry; Diploblastic - Cnidarians
Multicellularity; Bilateral symmetry; Triploblastic; Blastopore becomes anus - Deuterostomes (Echinoderms; Chordates)
Multicellularity; Bilateral symmetry; Triploblastic; Blastopore becomes mouth - Protostomes (Nematodes; Arthropods; Mollusks; Annelid worms; Flatworms)
List and describe the structure and function of the 4 major tissue types found in animal bodies.
Connective Tissues - Bone tissue; blood tissue; connective dermis tissue
Nervous Tissues - Nervous tissue in brain
Epithelial Tissues - Reproductive tissues
Muscle Tissues - Smooth muscle tissue; cardiac muscle; skeletal voluntary muscle
Describe and contrast radial and bilateral symmetry
Radial symmetry - Many planes of symmetry around the body axis
Bilateral symmetry - A single plane of symmetry runs from mouth to tail
Define cephalization and describe its relationship to bilateral symmetry
- Bilateral symmetry is correlated with cephalization (The concentration of sense organs, nervous control, etc., at the anterior end of the body, forming a head and brain, both during evolution and in the course of an embryo’s development.)
- Need to capture information from the environment: sensory receptors and to respond to it: motor functions
Identify major animal phyla that have a segmented body plan
annelids, arthropods & chordates
Define coelom and pseudocoelom
- Coelem - a body cavity, a fluid- or air-filled space located between the digestive tract and the outer body wall; A true coelom is lined on all sides by tissues derived from the mesoderm
- A pseudocoel is not lined on all sides by mesodermal derived tissues
Contrast the body plans of coelomate, acoelomate, and pseudocoelomate animals
Coelomate- Coelomates have a body cavity that is lined with mesoderm called the peritoneum. An example of a coelomate is phylum Chordata (such as tigers).
Acoelomate- Acoelomates have no true body cavity. An example of an acoelomate is phylum Cnidaria (such as sea anemones).
Pseudocoelomate- Pseudocoelomates have a pseudocoelom; that is, they have a body cavity, but it is not lined with mesoderm.
Describe the process of cleavage; Distinguish between spiral and radial cleavage
Cleavage is a series of mitotic cell divisions that transform the zygote into a blastula
Spiral cleavage - Early protostome embryo: its four cells are undergoing cleavages oblique to the original body axis
Radial cleavage - Early deuterostome embryo: its four cells are undergoing cleavages parallel with and perpendicular to the original body axis
Define blastula, blastopore, gastrula, germ layers, endoderm, ectoderm, mesoderm, diploblastic, triploblastic
Blastula - The end product of cleavage
Blastopore - the opening by which the cavity of thegastrula, an embryonic stage inanimal development, communicates with the exterior.
Gastrula - An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.
Germ Layers - a group of cells in an embryo that interact with each other as the embryo develops and contribute to the formation of all organs and tissues
Endoderm - the germ layer covering the surface of the embryo, gives rise to the outer covering of the animal and, in some phyla, to the central nervous system
Ectoderm - the innermost germ layer, gives rise to the lining of the digestive tract (or cavity) and to the lining of organs such as the liver and lungs of vertebrates.
Mesoderm - all bilaterally symmetric animals have a third germ layer, called the mesoderm, which fills much of the space between the ectoderm and endoderm; forms the muscles and most other organs between the digestive tract and the outer covering of the animal.
Diploblastic - Diploblastic animals have two germ layers (Endoderm; Ectoderm)
Triploblastic - Triploblastic animals have three germ layers (Endoderm; Mesoderm; Ectoderm)
Describe what happens during gastrulation and what is formed as a result of this process
In animal development, a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula.
Distinguish (similarities and differences) between protostomes and deuterostomes
Protostomes: Spiral Cleavage; Blastopore becomes mouth; Anus forms secondarily
Deuterostomes: Radial Cleavage; Blastopore becomes anus; Mouth forms secondarily
Describe the characteristics of Ponifera
Examples: Sponges
No body plan; no nervous system; filter feeding; intracellular digestion; no circulatory system; Respiration via diffusion across the body wall; support via spicules of calcium carbonate + protein fibers;
Key structures:
- choanocytes: flagellated cells that circulate water
- ostia: pores through which water enters
- oscula: opening through which water leaves
Describe characteristics of Cnideria
Examples: Jellyfish, Corals, Sea Anemones
No body plan; nerve net; feeding via predation + mutualistic association with algae; Gastrovascular cavity; No circulatory system; Respiration via diffusion across the body wall; Support system via mesoglea + hydrostatic skeleton + hard exoskeleton
Key Structures:
- Cnidocytes: specialized cells containing cnidae. The stinging structures of jellyfish (nematocysts) are an example of these.
* Polyp: sedentary, column shaped form with oral surface facing upward
* Medusa: free-swimming, umbrella shaped form with mouth oriented downward
* Diploblastic; radial body symmetry typical
