Invertebrate Zoology, Questions 1

Lecture 1 – Lecture 4 (Bauplans)

  1. What is a bauplan? To what aspects of an animal does its bauplan relate?
  1. List the major functions carried out by animal bodies. (NOTE: As we go through the course, you should be able to list these key functions and describe how the animal actually carries them out.)
  1. One point made in the introductory lecture is that animals have somewhat limited options for accomplishing necessary tasks. Provide an example.
  1. Another point made is that “a bauplan is a mix of ancestral and derived characters.” Provide an example.
  1. Animals are considered to have evolved from single-celled Protists. Describe at least two advantages of being an organism with >1 cell.
  1. “Multicellular” does not mean simply having >1 cell. What does it mean?
  1. What potentially limits size even in multicellular organisms? What adaptations do the more simple animals (i.e. Porifera and Cnidaria) have for overcoming this type of size limitation? What adaptations do more derived animals have for overcoming this type of size limitation?
  1. What advantages might a diploblastic animal have over an animal without true tissues (i.e. Porifera?) Conversely, now that you have studied the Porifera, what advantages might the Porifera have over animals with true tissues? (No correct answer, but THINK!)
  1. What advantages might a triploblastic animal have over a diploblastic one?
  1. Body cavities!
  2. What is a body cavity? Be precise!
  3. Do all triploblastic animals have a body cavity?
  4. List the key functions of a body cavity?
  5. Describe the key body-cavity related differences among the Acoelomates, Pseudocoelomates (=Blastocoelomates) and Eucoelomates. Provide at least one example of an animal found in each of these groups.
  1. Reynold’s numbers
  2. Write the formula for the Reynold’s number, and define each of the variables.
  3. Explain how size relates to Reynold’s number.
  4. How does the experience of an animal with a high Reynold’s number fundamentally differ from one with a low Reynold’s number, even if they are in exactly the same medium (i.e. both in seawater of the same salinity and density.)
  1. List the four key modes of locomotion of animals and their parts.
  1. Briefly describe amoeboid motion.
  1. Cilia/flagella
  2. How are cilia and flagella similar to each other? How do they differ?
  3. Are cilia and flagella generally associated with high or with low Reynold’s numbers? What makes them effective within this range of Reynold’s numbers?
  4. Sketch the arrangement of the microtubules of cilia/flagella.
  5. What are the dynein arms located, and what is their function?
  6. What allows cilia and flagella to bend rather than shorten like muscle fibers?
  7. What patterns of movement are generally seen in flagella?
  8. What patterns of movement are generally seen in cilia? What is a metachronal wave, and how does this motion pattern keep the organism (or particles) moving continuously in one direction?
  1. Hydrostatic skeletons
  2. What property of water allows hydrostatic skeletons to be effective at providing structure?
  3. Provide a step-by-by step description of peristaltic movement in an earthworm, being sure to include which muscles are contracting and where the fluid shifts as a result. Also explain the role of anchoring hairs (called setae.)
  4. What is the role of diagonally or helically-oriented muscle fibers in hydrostatic skeletons?
  1. Name the two categories of rigid skeletons, and explain the difference. Also provide an example of each type.
  1. What is meant by an articulated skeleton? Provide an example from a mollusc as well as from an arthropod.
  1. How do the origin and insertion points of a muscle differ? Do muscles of hydrostatic skeletons have clear origins and insertions?
  1. List and compare (both similarities and differences) the three types of digestion, and provide an example of each.
  1. What is the key difference between suspension and deposit feeding?
  1. What is excretion? Specifically, which types of wastes are excreted?
  1. Why are nitrogenous wastes excreted if the body, in fact, needs nitrogen to build proteins?
  1. What are the three nitrogen-contained waste products that are excreted from animals? Also, compare them in terms of their solubility in water, relative toxicity and whether they are most effective in water vs. terrestrial environments. Also, which of these is relatively uncommon in invertebrates?
  1. Sketch the movement of both water and salts into/out of invertebrates for each of the following environments:
  2. Fresh water
  3. Salt water (marine)
  4. Terrestrial

  1. Osmoconformers vs. osmoregulators
  2. What is the difference between an osmoconformer and an osomregulator? (Yep, I’m just looking for a simple answer here…)
  3. Create a graph that compares the response of a perfect osmoregulator with a perfect osmoconformer when subject to water of varying salinity. Be sure to label your axes!
  4. Are there limits to the ability of osmoregulators to regulate their water and ion balance? Explain/graph.
  5. Do osmoconformers have some ability to osmoregulate? Explain/graph.
  6. Explain how an individual cell could osmoregulate, albeit in a limited way.
  1. What is a common osmoregulatory structure in freshwater protists, and probably also present in freshwater sponges?
  1. What are nephridia? What is the key difference between protonephridia and metanephridia?
  1. What is the value of circulation within an animal? What key types of substances are transported?
  1. Provide some examples of circulation within the body of an animal other than within a true circulatory system.
  1. What is the key difference between an open and a closed circulatory system? Which type is correlated with a well-developed coelom? Where does exchange of dissolved materials between the blood and the tissues take place for closed circulatory systems? Where does exchange of dissolved materials between the circulating fluid and body tissues take place for open circulatory systems?
  1. List, briefly compare the three types of hearts/pumping mechanisms.
  1. What is the difference between myogenic and neurogenic control of contraction?
  1. Where is the circulatory fluid generally pumped right after it is oxygenated?
  1. “Go with the flow…”
  2. Which flow rate would be most effective for transport of fluids, relatively high or relatively low?
  3. Which flow rate would be most effective for exchange of dissolved materials (i.e. dissolved gas, etc…), relatively high or relatively low?
  4. How is it possible to have a low flow rate over capillary beds, given that each capillary is much narrower than the arteries and arterioles that feed them?
  1. Why must gas exchange surfaces be moist? What else do gas exchange structures/surfaces have in common?
  1. What is the function of respiratory pigments? Are the respiratory pigments associated with cells, dissolved in the circulatory fluid or both? Is there any commonality between the respiratory pigments of invertebrates and those of vertebrates? Explain. (NOTE: Except for hemoglobin, you don’t need to yet memorize the different pigments. We may cover some more specifically when we get to various organisms.)
  1. How is carbon dioxide transported (i.e. in what forms) and is it generally associated with cells or dissolved in the fluid?
  1. List several different types of receptors and indicate the type of stimulus associated with each receptor type.
  1. What types of asexual reproduction occur in invertebrates? Provide a couple of examples.
  1. What is a colony? Is an “ant colony” a true colony according to this definition?
  1. Define the following:
  2. Gonochoristic
  3. Protandrous hermaphrodite
  4. Protogynous hermaphrodite
  5. Simultaneous hermaphrodite
  1. What is parthenogenesis? What does it have in common with sexual reproduction? What does it have in common with asexual reproduction?
  1. In the aphid life cycle, of what adaptive value is parthenogenesis? Think especially about the parthenogenic reproduction that occurs via the original stem mother that hatches from the resting egg. In contrast, of what adaptive value is the sexual reproduction that occurs once per year?

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