Porifera Quiz Questions 1. What structures give sponges their support? Cacareas: spongin, a proteinaceous substance. Spicules, CaCO3. Hexactinelidae: SiO2, Siliceous hexactines 2. What cells are responsible for moving water, nutrients, and wastes through the sponge? Amoebocyte: waits in mesohyl, carry food/nutrients. compensate for lack of circulatory system Choanocyte (or collar cells), collar, flagella- food is phagocytized Epithelial cell: cells lining non-flagellated edge of sponge Mesoglea 3. What are the three body forms of sponges, from least to most complex? Demospongae- bath sponges, lack calcareous/siliceous spicules. Many visable oscula (excurrent, large holes) and ostia (incurrent). Calcarea- Hexactinellida- SiO2, silicon oxide. 'Glass sponges'. Nearly all are deep-water. 4. Water enters sponges through openings called __________ and exits via __________. ostia, oscula 5. The sponges are thought to have evolved from what colonial ancestors? choanoflagellates Invertebrate Animal Diversity Study Guide How did we get all of this invertebrate diversity? What are the events that have led to today’s diversity? What is the Cambrian Explosion and what are some potential causes for it? What are some extinct groups of organisms that are related to living organisms now? How can ancestral relationships be illustrated on phylogenetic trees? What are sister taxa and how can you recognize them on a phylogenetic tree? What are clades and can you recognize them on a tree? Can you recognize older diversification events versus younger ones on a tree? What is the common ancestor to all Metazoan life and what evidence supports this hypothesis? Distinguish between plesiomorphies, synapomorphies, and autapomorphies and give some examples in different groups. plesiomorphic: the primitive or generalized characteristics that arose early in the evolutionary history of a taxonomic group. Example would be multicellularity in metazoans. synapomorphic: an apomorphy (derived/specialised character) shared by 2+ groups that originated in their last common ancestor. Example: bilateral autapomorphic: a derived trait, unique to a given taxon. cnidocytes in cnidarians What are the major extinction events and how have they affected diversity? What are the main body plans of Poriferans? How do surface area:volume relationships affect the size of an organism? Distinguish between multicellularity and coloniality. What advantages to colonial organisms have over solitary organisms? What are some unique features of freshwater organisms to deal challenges they face in their environment? Discuss feeding and defense in Cnidarians. Compare and contrast swimming and locomotion in Scyphozoans and Ctenophores. What is a hydrostatic skeleton? How is it involved in feeding and locomotion? How does a neural net allow for differential cell signaling? What are some examples of mutualism and how does each partner benefit? Discuss bioluminescence. What organisms display this and how does this benefit the organisms? Discuss reef-building in sponges and corals. How are they similar? Why are they important? What is coral bleaching? What are some of the causes? How do protostomes and deuterostomes differ in their development with respect to cleavage, blastopore development, tissue layer organization, and cell fate? How are tissue layers arranged in coelomates, acoelomates, and pseudocoelomates? How do coelomic spaces aid in digestion and locomotion? How do antagonistic muscles control movement in hydrostatic skeletons? What are some adaptations seen in meiofauna and how do they relate to their ecology? What is cryptobiosis? Discuss the relationships of the Lophophorates and Trochozoans. What are some advantages of metamerism? What are some examples of different waste removal systems? How do Annelid body plans relate to their habitat and locomotion? Discuss some feeding strategies of Annelids and Annelid allies. How do leeches differ from other Annelids with respect to body morphology, locomotion, feeding, and reproduction? How do Sipulculids, Echiurans, and Pogonophorans feed and obtain energy? Compare and contrast body morphologies among the worm-like trochozoans. What is the HAM and how does it compare to body morphologies seen in different Molluscan classes? What are some criteria that make invertebrates good biomonitors and bioindicators? What are the functional tagma in arthropods? What are the key features of exoskeletons? How do exoskeletons allow for movement? Discuss the 5 steps of molting. How do hormones control molting in insects and crustaceans? What are some adaptations that have allowed for terrestrialization? What are 5 hypotheses regarding the evolution of wings from protowings? Explain ametabolous, hemimetabolous, and holometabolous development in insects. Compare and contrast tube-foot positioning in Echinoderms. What are the key Chordate features? Discuss jet propulsion. Which organisms use jet propulsion? How do Larvaceans feed? This exam is worth 50 points, 25% of lecture grade. Shorter Essay: Answer 3 of 4. (18/50 points). Provide short statements, figures, or lists. 5 points each. 1. (6 pts) Why are sponges sometimes considered colony of unicells (protozoans) or ’parazoa,’ rather than metazoans? What do they lack? Parazoa because celles are somewhat independent, can dissociate and reaggregate, use phagocytosis, and lack many metazoan features: basal lamina, gut, muscles, nerves (elaborate cell specialization, connective tissue) 2. (6 pts) What characteristics do Anthozoan polyp and Scyphozoan medusa share? How do they differ from Hydrozoan polyps and medusae? Anthozoan polyp and Scyphozoan medusa share: gastrodermal gonads, septate gut, nematocysts in gastrodermis, pharynx lined with ectoderm, mesoglea cellular and thick Hydrozoans differ: coelenteron simple, mesoglea thin and acellular, epidermal and gastrodermal gonads, hydromedusa with velum ( colonial polymorphism) 3. (6 pts) Describe the developmental processes, and the external and internal body plan features associated with a bilateral body plan, using 'worms' as an example. Features: Developmental: Gastrulation, triploblastic External and internal: bilateral symmetry, longer than thick, longitudinal and circular muscles, longitudinal nerves, Cephalization, mobility, body cavity Dorsal/ventral axis in addition to anterior/posterior 4. (6 pts) Describe a typical trematode life cycle. How does it differ from the life cycle of a parasitic nematode? Trematode life cycle: two or more hosts, vertebrate definitive (final) host (adult fluke) sexual phase, eggs liberated sometimes forming a miracidia stage that invades intermediate host. Asexual phase of trematode with several stages in the Intermediate host. (Asexual stages include redia, sporocyts, cercaria). Cercaria shed and swims to another intermediate or definitive host, may include metacercaria. Nematode: in contrast, may be plant parasites, and ectoparasites, not as many larval stages, some with eggs and free-living larva stage in soil, (some species are both plant and animal parasites). Essay questions. Answer 2 of 3. Each question is worth 16 pts. 1. (16 pts) Compare the Symbiotic, Cellularization, or Colonial theories for the origin of metazoans in general. What are the strengths of weakness of each theory? Which theory most likely explains the origin of Sponges. Which protozoan group is the likely ancestor of Sponges? 3 x 4pts Symbiotic: two or more different protozoan species form an association and a multicellular individual (e.g. an amoeba and a flagellate). Strength: explains the presence of different types of cells (amoebocytes, flagellated cells) in metazoans like sponges Weakness: requires an advantage to association for both species because a loss of reproductive fitness is likely for one of the species. Cellularization: from a multinucleate single cell to multicellular after the partitioning of cytoplasm and nuclei by cell membranes Strength: ciliates form a multinucleate state during sexual reproduction Weakness: cellularization is not seen in protozoans or in the early development of any metazoan. Only ciliates form a multinucleate state, but Sponges and Cnidarians have flagellated cells Colonial: single cell divides asexually to form a colony of daughter cells. Specialization of cell function leads to multicellular individual. 4pts For sponges: colonial theory most likely— cellularization theory is probably not correct-- ancestor was probably a flagellate. Choanoflagellates protozoan cells have a similar microvillar-collar and single-flagella structure, and some are colonial. DNA evidence shows close relationship between sponges and choanoflagellates. The blastula stage of metazoans may reflect a blastea ancestor that was similar to Colonial flagellates like Volvox. EXTRA CREDIT: Larval stages do not reflect the blastea ancestor because anphiblastula begins with inward-directed flagella, and parenchymula larva is flagellated on outside but solid (stereoblastula) (Sponges resemble loose colonies of unicells, given their cell independence, ability to reaggregate.) 2. (16 pts) The Cnidarians are puzzling because the class with the simplest life-cycle has the most complex polyp form, and this complicates any conclusion about the evolutionary relationships among the classes. Which class and which life cycle do you believe is ancestral? Describe two hypotheses for the relationships among these classes, and their strengths and weaknesses. This question was argued both ways. Polyp-only first (Medusazoa) hypothesis: Anthozoan is ancestral. This is supported by cladistic parsimony using 18S, 16S and morphological data. However, Anthozoans have the most complex polyp form (septa in coelenteron, cellular mesoglea) and the sexual phase occurs in the polyp but in the medusa in Medusazoa. Can evolution lead to simplification, and the transition to sexual reproduction in the Medusa? Medusa-only first: Hydrozoans ancestral Hydrozoans are the simplest polyp form, and Anthozoans are derived under this hypothesis, thus is consistent with an evolutionary trend of greater complexity. This hypothesis also accounts for the similarity between Scyphozoans and Anthozoans. Hydrozoans also display a full range of life-cycles, which might form the stem groups for the two other classes. Life-cycle of Aglaura sp. may be ancestral. Transition of sexual stage in medusa to polyp in Anthozoanscould occur by the settlement of an actinula or planula, and paedomorphosis to get a sexual polyp. 3. (16 pts) What are some similarities and differences between the free-living Platyhelminthe and Nemertean worms? Do you think they are closely or distantly related and why? What characteristics point to a close relationship between these two groups? To a distant relationship? Similarities and close relationship: apparent acoelomate solid body (Parenchyme), flat body plan, protonephridia, rhabdites, ciliated ectoderm Differences: Nemerteans have a closed blood/circulatory system, complete gut, rhynchocoel and proboscis, nerve ring around rhynchocoel, and rhynchocoel is mesoderm-lined like a true coelom Close relationship: the similarities above Distant relationship: differences above, plus ribosomal RNA sequence shows Nemertean related to coelomates, rhynchocoel and blood vessels seem to be remnant coelomic spaces Zool 322: Exam I study questions (NOTE, when the question asks "Why or Why not?", you will want to think about the following questions: What are the strengths of this conclusion? What evidence suggests it is true? What evolutionary transitions must be envisioned? 1.Trace the probable origins of sponges. Which protozoan group is the most likely ancestor of Sponges? Why? Describe the pattern of similarities and differences that lead to your conclusion. 2. Do you think the Symbiotic, Cellularization, or Colonial theory is correct, and why? What are the strengths and weaknesses of the Colonial theory in explaining the origin of Porifera? 3. Why are sponges sometimes classified in a group called "Parazoa"? Are sponges unicellular colonies, or multicellular individuals? Which aspects of sponges suggests that they are unicellular colonies, rather than multicellular individuals? 4. What characteristics do Anthozoan polyps and Scyphozoan medusa share in common? How do they both differ from Hydrozoan medusae? Which body plan and class seem like they have the simplest structures? Which body plan probably is ancestral for Cnidarians (polyp only, or medusa only)? 5. Describe the patterns in the variation of life-cycle polymorphism seen in the Hyrdozoans. Which life cycle is the most ancestral, and why? 6. Which Cnidarian class might be most ancestral? What are the strengths and weaknesses of the alternative theories? 7. According to the Polyp-first (Medusazoa) theory, Anthozoan relatives are the ancestral group of Cnidarians. Do you think this is the most likely scenario? Why or why not? 8. Do you think the Medusa-first theory is most likely? Why or why not? 9. What characteristics indicate a close relationship between Ctenophores and Cnidarians, and in what ways do these groups differ? 10. The transition to bilateral symmetry is associated with a number of developmental and morphological traits. What are they? Describe the bilateral body plan. What external and internal features are associated with a bilateral body plan? Explain how the worm body plan is an example. 11. Describe the organ systems in Platyhelminthes that are significantly more complex than those found in Cnidarians. 12. Describe three ways to derive Platyhelminthes from different ancestors (from protozoans, diploblasts, and triploblasts). Which show a trend of increasing complexity versus a trend of simplification? What did the 18S rRNA data show? Which do you think is most likely? 13. Compare the similarities and differences between the life cycles of parasitic trematodes and parasitic nematodes. 14. What are some similarities and differences between the free-living Platyhelminthe and Nemertean worms? Do you think they are closely or distantly related and why? What characteristics point to a close relationship between these two groups? To a distant relationship? A) HYDROZOA B) CUBOZOA C) SCYPHOZOA D) ANTHOZOA E) OBELIA F ) PHYSALIA 7. _______ dominant medusa stage 8. _______ dominant polyp stage 9. _______ has scyphostomes 10. _______ colonial 11. _______ planula larvae 12. _______ produces skeletal material SECTION 2. SHORT ANSWER. PROVIDE CONCISE ANSWERS WITH GOOD CONTENT (5-10PTS each). 13. COMPARE and CONTRAST MICROEVOLUTION and MACROEVOLUTION. Make sure you include TIME, SPACE, and SCALE of organism diversity (species level, phylum level, etc..). A good answer would describe what micro and macroevol. are wrt timescale and spacescale, mentioning processes (e.g., natural selection, adaptation, speciation, extinction) and patterns -- geographic variation, species differences, mass extinction, radiations -- etc... 14. SPONGES are said to have a CELLULAR LEVEL of ORGANIZATION, whereas CNIDARIANS are organized at the TISSUE LEVEL. Discuss what this means. Cite specific cells, extracelluar materials, cell layers, structures, and "tissues" that each have to support your answer. A good answer would describe the what tissues are, and discuss the forms/functions/locations of specific cells, materials, layers, etc... found in the 2 groups. Mention of germ layers (endo, ecto, meso) and how they differ in the 2 lineages wrt the level of organization.... etc... 15. What was was the significance of the CAMBRIAN EXPLOSION that apparently occurred during the EDIACARAN (represented in North America by the Burgess Shale fossil deposits) ? Why is this – or WHY IS THIS NOT -- an example of ADAPTIVE RADIATION ? A good answer would describe the Cambrian explosion (about 600 mya) and what it represents. In answering if it is an example of Adaptive radiation, you would be explaining what adaptive radiation is... etc... 16. WHY DOES SIZE MATTER? Discuss the major physical factors that effect LARGE versus SMALL organisms. How is SURFACE AREA and VOLUME effected as a small organism becomes LARGER during EVOLUTION ? What is the significance of surface area to volume ratios? A good answer would describe the important effects of size, including esp. the impact of gravity. Discussion of surface area/vol should include some biological/physiological impacts... etc... 17. DESCRIBE the LIFE CYCLE of one the following ORGANISMS. Make sure you include – a) the organisms scientific name, b) how it enters its host(s), c) what host(s) they have, d) where they go within the host and e) how they exit the definitive (last) host. PLASMODIUM, TRYPANOSOMA CRUZI, GIARDIA A good answer would describe the cycle with the a-e parts included -- possibly a good diagram (clearly labeled) would work well ... etc... 18. Cnidarians that form HYDROPOLYP COLONIES (Obelia) have a variety of polyp forms that have dramatically different forms and functions. DISCUSS the FORM and FUNCTION of the following: a) GASTROZOIDS, b) GONOZOIDS, c) DACTYLZOOIDS. A good answer would show that you understand that these different polyps have different biological roles. Your description of their forms (anatomy) leads to defining their function... etc.... 19. Cnidarians have a nervous system, including simple sense organs. DESCRIBE the FORM, FUNCTION, and LOCATION of SENSE ORGANS in a typical SCHYPHOZOAN MEDUSA. A good answer would describe statocyts and ocelli, including their specific location in schypozoan medusae... etc... 20. COMPARE and CONTRAST the body plans of CTENOPHORES and CNIDARIANS. How are they similar and how do they differ? Why have these 2 phyla been considered together traditionally, and why do we now believe they are only distantly related ? A good answer would address the major body plan similarities (esp. radial symmetry) and discuss whether this might be homologous (indicating close relationship) or convervgent (including distant relationship)....etc... 21. COMPARE and CONTRAST the body plans of ASCONOID, SYCONOID, and LEUCONOID sponges. How are they similar and how do they differ ? A good answer would describe what micro and macroevol. are wrt timescale and spacescale, mentioning processes (e.g., natural selection, adaptation, speciation, extinction) and patterns -- geographic variation, species differences, mass extinction, radiations -- etc... 22. COMPARE and CONTRAST the body plans of typical free-living HYDROPOLYP (e.g., Hydra) versus a ANTHOZOAN (e.g., sea anemone). How are they similar and how do they differ ? A good answer would really focus on the similarities / differences. E.g., both are polyp-dominated forms but anthozoans have siphonoglyphs, "retractor muscles", and a thick mesodermal layer and Hydra are much simpler. 23. Look at the CLADOGRAM (phylogenetic hypothesis) shown below. If one was to try to group species A, B, and C, would they be a monophyletic, paraphyletic, or polyphyletic group ? If one was to group species A, B, and D, would that group be monophyletic, paraphyletic, or polyphyletic ? Why should we prefer classifications that are based on monophyletic groups ? A B C D E | | | | | |______| | |_______ | | | | | | | |__________| | | | |___________________| | A good answer would correctly identify A,B,C, as monophyletic and A, B, D, and paraphyletic (see Chapt. 3) and explain the power of classifying based on groups supported by data ... etc... 24. What is the significance of GASTROVASCULAR CAVITIES ? What is it, what organisms possess them, where are they located (in those organisms) ? The GVC is said to be a major evolutionary innovation – HOW is it an innovation, i.e., what major function does it contribute to organisms during the history of life on earth ? A good answer would explain would a GVC is, who has them, and its major function (and why that function is special) ... etc... SECTION 3. FILL-IN. PROVIDE CONCISE ANSWERS WITH GOOD CONTENT ( 3 PTS each). 6 MAJOR PORIFERAN CHARACTERISTICS 6 MAJOR CNIDARIAN CHARACTERISTICS