Intro to Animals 1. Soon after gastrulation, a researcher injects a dye into the developing anus of a deuterostome embryo. Initially, the dye should be able to flow directly into the ________. a. archenteron 2. A researcher is trying to construct a molecular-based phylogeny of the entire animal kingdom. Assuming that none of the following genes are absolutely conserved, which of the following would be the best choice on which to base the phylogeny? a. collagen genes 3. In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at is a protostome and not a deuterostome? a. You see a mouth, but not an anus. 4. Which of the following would you classify as something other than an animal? a. choanoflagellate 5. While looking at some seawater through your microscope, you spot the recently fertilized egg of an unknown animal. Which of the following tests could you use to determine whether the developing organism is a protostome or a deuterostome? See whether the embryo ________. a. exhibits spiral cleavage or radial cleavage 6. Which tissue type or organ is NOT correctly matched with its germ layer tissue? a. nervous—mesoderm 7. What is absent in a diploblastic animal? a. mesoderm 8. What do all deuterostomes have in common, not found in other animals? a. The pore (blastopore) formed during gastrulation becomes the anus. 9. Collectively, coelomates (animals with coeloms) form a monophyletic group. a. False 10. Arthropods invaded land about 100 million years before vertebrates. This fact most clearly implies that ________. a. arthropods have had more time to coevolve with land plants than have vertebrates 11. If you think of the earthworm body plan as a drinking straw within a pipe, where would you expect to find most of the tissues that developed from endoderm? a. Lining the straw 12. Whatever its ultimate cause(s), the Cambrian explosion is a prime example of ________. a. Adaptive radiation 13. Which is a correct sequence of the stages of animal embryonic development? a. Morula, blastula, gastrula, germ layer development Invertebrates Part A 1. What is true of all eumetazoans? a. They have tissues 2. An embryo that develops an anus before a mouth is most certainly going to be in the clade a. Deuterostomia 3. Which is NOT in the clade bilateria? a. Hydrozoa 4. A hydrozoan that is attached to a surface is in a ________ stage. a. polyp 5. Tapeworms are in the clade ____________. a. Platyhelminthes 6. Blood flukes are transmitted by ___________. a. penetrating skin 7. Most animals are vertebrates. a. False 8. Which sponge cells are most similar to the most recent protist ancestor of animals? a. choanocytes 9. Which sponge cells are motile within the sponge body? a. amoebocytes 10. Which is a feature of a Cnidarian body? a. one opening to the digestive cavity 11. Anthozoans are _____________. a. cnidarians 12. What would be the most effective method of reducing the incidence of blood flukes in a human population? a. reduce the population of the intermediate snail host 13. Which of the following can be found in the mesohyl of a sponge? a. amoebocytes and spicules 14. Which is NOT a mollusc? a. Brachiopod 15. Animals in the phylum Porifera are ____________. a. filter feeders 16. Which is a feature of a Cnidarian body? a. coelenteron 17. Which characteristic is shared by cnidarians and flatworms? a. a digestive system with a single opening 18. Snails are in the clade ____________. a. Mollusca 19. A clam's shell is secreted by its ___________. a. mantle 20. Earthworms are in the clade ____________. a. Annelida 21. An animal with no true tissue is in which lineage? a. Porifera 22. A swimming sea jelly is in the clade ___________. a. Medusozoa 23. Tapeworms are transmitted by ___________. a. Eating undercooked meat Invertebrates Part B 1. The arthropod exoskeleton is made primarily of ____________. a. chitin 2. Lobsters are in the clade ______________. a. Pancrustacea 3. Sea stars are in the clade _____________. a. Asteroidea 4. _____________are an extinct lineage of marine animals. a. Trilobites 5. The lineage known for shedding their exoskeleton is ____________. a. Ecdysozoa 6. Spiders are in the clade ______________. a. Chelicerata 7. Brittle stars are in the clade _____________. a. Ophiuroidea 8. Feather stars are in the clade _____________. a. Crinoidea 9. Arthropods have an open circulatory system a. True 10. Trichinosis is caused by a ___________. a. nematode 11. Insects are ________. a. Hexapods 12. _____________are known to withstand extreme conditions, even outer space. a. Tardigrades 13. Shrimp and crabs are ________. a. Decapods 14. A digestive tube with both a mouth and an anus is a/an___________. a. Alimentary canal 15. Some chordates are invertebrates. a. True 16. Myriapods with two pairs of legs per body segment are ______________. a. Millipedes 17. Sea stars are a. Echinoderms 18. Which is NOT a pancrustacean? a. Horseshoe crab 19. Centipedes are in the clade ______________. a. Myriapoda 20. Sea cucumbers are in the clade _____________. a. Holothuroidea 21. _____________ is used in research on genetics and cellular biology. a. Caenorhabditis elegans 22. Sea urchins are in the clade _____________. a. Echinoidea 23. Pill bugs are ________. a. Isopods Vertebrates Part A Open Notes Quiz 1. To reproduce, many plants produce seeds—structures containing embryonic offspring along with nutrients inside a tough coat. These offspring develop after being released by the parent plant. To which animal reproductive "strategy" is seed production most comparable? a. oviparous reproduction 2. Tiktaalik was an exciting fossil discovery that showed an animal with a. traits like a fish and traits like a tetrapod 3. Which of the following is a characteristic of all chordates at some point during their life cycle? a. post-anal tail 4. What is the function of a swim bladder in fishes? a. controlling buoyancy 5. Vertebrates and tunicates share ________. a. a notochord and a dorsal, hollow nerve cord 6. Ray-finned fishes are in the clade ______________. a. Actinopterygii 7. An animal in which the offspring develop within eggs yet the eggs hatch within the uterus is ________________, a. ovoviviparous 8. It is believed that the coelacanths represent a crucial link between other fishes and tetrapods. What is the major feature in these fish in support of this hypothesis? a. Their fins have skeletal and muscular structures similar to amphibian limbs. 9. Which is NOT a derived trait of tetrapods? a. Jaw 10. Placoderms are ___________________. a. gnathostomes 11. At one time, Chondrichthyes were thought to have split off from other vertebrates before the evolution of bone. Now we have concluded that the Chondrichthyes split off after the evolution of bone had started. This change demonstrates ________. a. as new evidence emerges, scientists revise their hypotheses 12. Myxini are ____________________. a. cyclostomes 13. Which of the following could be considered the most recent common ancestor of living tetrapods? a. a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates 14. Which extant chordates are postulated to be most like the earliest chordates in appearance? a. lancelets 15. Which is FALSE about Coelacanths? a. They are extinct. 16. Which is NOT a Sarcopterygii member? a. tuna fish 17. Why do skates and rays have flattened bodies, while sharks are torpedo shaped? a. Sharks are streamlined for active swimming at mid-depths, while skates move about mostly on the ocean bed. 18. Which animal has a jaw? a. chondrichthyan 19. Which is NOT an osteichthyan? a. Sharks 20. An animal with a cartilaginous skeleton, flat body, and a whip-like tail is probably a/an __________. a. Ray 21. Chordate pharyngeal slits appear to have functioned first as ________. a. Suspension-feeding devices 22. Which is NOT a derived character of vertebrates? a. Notochord 23. What is NOT one of the functions of a cloaca? a. Oxygen exchange Vertebrates Part B 1. Which of the following are the only extant animals that descended directly from dinosaurs? a. Birds 2. A trend first observed in the evolution of the earliest tetrapods was ________. a. feet with digits 3. The oldest known bird is ____________. a. Archaeopteryx 4. Which of the following statements about the geographic distribution of marsupials is accurate? a. they occur in Australia and the Americas 5. Which is NOT a hominoid? a. New world monkey 6. Primate evolution and behavior, such as hunting skills, have been directed in part by the development of depth perception. What anatomical change made depth perception possible? a. location of the eyes at the front of the head 7. A vertebrate with four legs, a tail, and can "breath" through its skin is in the clade ______________. a. Urodela 8. What group of mammals have (a) embryos that spend the most time feeding through the placenta than the mother's nipples, (b) young that feed on milk, and (c) a prolonged period of maternal care after leaving the placenta? a. Eutheria 9. A vertebrate with four legs,no tail, powerful hind legs, and can "breath" through its skin is in the clade ______________. a. Anura 10. Unlike eutherians, both monotremes and marsupials ________. a. have some embryonic development outside the uterus 11. Which of these are amniotes? a. Turtles 12. Which characteristic is common to all the modern representatives of all major reptilian lineages (turtles, lepidosaurs, crocodilians, and birds)? a. Presence of a notochord 13. An extant endothermic diapsid is a __________________. a. Bird 14. Which clade does not include humans? a. Diapsids 15. During chordate evolution, what is the sequence (from earliest to most recent) in which the following structures arose? a. Jaws, swim bladder, amniotic egg, mammary glands Short Answers: Question 1 Name and describe each stage of an embryo’s development. 1. Zygote undergoes a series of mitotic divisions called cleavage 2. After 3 mitotic divisions, the 8-cell stage occurs 3. There are 16 cells called a morula, and during the first couple of divisions, the cells are totipotent, meaning they can form any tissue and are undifferentiated 4. At over 100 cells, the ball becomes a hollow blastula, with each cell being a blastomere. The hollow interior is a blastocoel. Blastomeres are pluripotent and can give rise to most cell types 5. Gastrulation occurs, where the ball of cells fold inward forming the gastrula 6. Three germ layers develop, and the ectoderm (outer layer that forms dermal and nervous organs) and endoderm (inner layer with tissues developing into digestive tract) form 7. The two germ layers are separated by the blastocoel, a fluid-filled cavity 8. The pouch formed is the archenteron and the opening is the blastopore TLDR: zygote cleavage, 8 cell stage to 16 cell morula, then hollow blastula which folds inward to form gastrula, then 3 germ layers develop, and two of them separate and a pouch is formed with the opening being the blastopore Question 2 Contrast protostome and deuterostome development in terms of the origins of the mouth and anus, the patterns of cell division, and the relative amount of time it takes the embryo’s cell’s fate to be determined. Triploblastic animals can be characterized as having protostome or deuterostome development. In protostome development, cleavage is spiral, meaning it has planes of cell division diagonal to the vertical axis of the embryo. On the other hand, deuterostome development is radial: planes of cell division are either parallel or perpendicular to the vertical axis of the embryo. In protostome development, cleavage is determinate- the developmental fate of cells is determined early on. In deuterostome development, cleavage is indeterminate, meaning each cell in the early stages of cleavage retains the capacity to develop into a complete embryo. In protostomes, the mouth develops from the blastopore and in deuterostomes, the anus does. Examples of protostomes are molluscs and annelids, and examples of deuterostomes are echinoderms and chordates. TLDR: Deuterostome: radial, indeterminate, anus develops from blastopore. Protostome: spiral, determinate, mouth develops from blastopore Question 3 Describe the synapomorphies that are shared amongst members of 1) Eumetazoa (what differentiates Eumetazoa from the basal lineage of Metazoa?) 2) Bilateria (what differentiates Bilateria from the earlier lineages?) 3) Deuterostomia (what trait is certain to be found in members of Deuterostomia, even if not exclusively?) 4) Lophotrochozoa (what characters might be found in members of Lophotrochozoa?) 5) Ecdysozoa (what character is found in members of Ecdysozoa, even if not exclusively?) Eumetazoa is a clade of animals with true tissues. Basal eumetazoans have radial symmetry and are diploblastic. Examples of this are cnidaria like jellyfish. There are also bilaterians, which have 3 germ layers (triploblastic) and are bilaterally symmetrical. This includes most animals. Deuterostomia includes hemichordata, echinodermata, and chordata. All have deuterostome development. Lophotrochozoa is a clade of bilaterian invertebrates. Some have a feeding structure called a lophophore, or a mouth with a crown of ciliated tentacles that sweep in food. Others go through a distinct developmental stage called the trochophore larva. This includes molluscs and annelids. Ecdysozoa is a clade of invertebrates that, as they grow, shed their exoskeletons through molting. This includes nematodes and arthropods. TLDR: Eumetazoa have true tissues. Basal eumetazoans have radial symmetry and are diploblastic. Deuterostomia have deuterostome development. Lophotrochozoa have lophophores that sweep in food or go through trochophore larva stage. Ecdysozoa molt. Question 4 State the derived traits (i.e. vertebrae, round mouths, jaws, etc) of each major chordate clade (chordates, vertebrates, cyclostomes, gnathostomes, and so on) and describe the relative adaptive advantages that each derived trait confers to the clade. For example, describe why vertebrate chordates have an advantage over invertebrate chordates, why gnathostomes have an advantage over cyclostomes, and so on. There are 4 derived characters of chordates, including notochords, a dorsal, hollow nerve cord, pharyngeal slits or clefts, and a muscular, post-anal tail. Vertebrates are chordates that have a backbone. The vertebrae that enclose the spinal cord have taken over the mechanical roles of the notochord. A skeletal system and complex nervous system have allowed vertebrates efficiency at capturing food and evading predators. Gnathostomes have jaws with teeth that can grip and slice food, an adaptation that likely evolved by modification of the skeletal rods that supported gill slits. On the other hand, cyclostomes are jawless vertebrates. They have toothlike formations in their mouths, but no jaw. Most are bottom dwelling scavengers rather than hunters. TLDR: Vertebrates are chordates that have a backbone. A skeletal system and complex nervous system have allowed vertebrates efficiency at capturing food and evading predators. Gnathostomes have jaws and cyclostomes do not, therefore gnathostomes have an advantageous adaptation. Question 5 Name and explain the function of each of the extraembryonic membranes of the amniotic egg. Explain why the amniotic egg allowed for amniotes to reproduce on land and why non-amniotic tetrapods cannot. Compare the amniotic eggs of amniotes to the seeds of seed plants in terms of the advantage they confer. The extraembryonic membranes within the shell are the amnion, chorion, yolk sac and allantois. The allantois is the disposal sac for certain metabolic waste produced by the embryo. The chorion is the exchange gasses between the embryo and air (along with the allantois) The amnion provides a fluid filled cavity that protects the embryo against mechanical shock. The yolk sac contains nutrient rich yolk (other nutrients are in the albumen). The amniotic egg allows for gasses such as oxygen and carbon dioxide to pass through the shell, but liquid is held inside to prevent the embryo from drying out. If you look at amphibian eggs that don’t have an amnion, the eggs will dry out if they were laid on land. The larvae of most amphibians have gills in order to survive in moist environments and will undergo a metamorphosis. The amniotic egg and the seed of a plant are very similar. They both provided protection from desiccation and nutrients for the developing embryo. Question 6 Compare monotremes, marsupials and eutherians in terms of their means of protecting and providing for their developing young. Why do eutherians dominate most habitats where mammals exist as opposed to the other two groups? Why is this not so in Australia? Monotremes are a small group of egg laying mammals. The females lack nipples and secrete milk from glands on their bellies. The baby sucks milk from the mother’s fur. The newborn baby is tiny and will stay in the pouch for several weeks and continues to develop. Marsupial embryo develops within the mother’s uterus and is nourished by the placenta. They are born very early in their development and complete their embryonic development while nursing in the maternal pouch. Eutherians are placental mammals because placentas are more complex than those of marsupials. They will have a longer pregnancy than marsupials. Young eutherians complete their embryonic development within the uterus, joined by their mothers by the placenta. This creates a longer lasting and intimate association between the mother and the developing young. During the Mesozoic era, marsupials were on every continent because there were land bridges connecting the continents. As the continents began to drift, it was hard for the newly arrived eutherians to disperse why most of them are found where mammals exist. South American and Australia became isolated and prevented eutherians from reaching Australia. This allowed marsupials to dominate. Marsupials in Australia look so much like eutherians on other continents due to convergent evolution.