Concept explainers
Fierce debate centers on whether ctenophores or sponges are the earliest-diverging animals. Choanoflagellates, the closest living relatives to animals, appear very similar to the choanocyte cells of sponges. In addition, sponges lack true tissues, although they have distinct types of cells. In contrast, all other animals possess one or more types of tissues. Both the Cnidaria and the Ctenophora are radially symmetric and, until very recently, both were thought to have only two germ layers, endoderm and ectoderm. All other animals are bilaterally symmetric and have three germ layers. Draw an animal phylogenetic tree that illustrated this viewpoint, including Cnidaria and Ctenphora as part of the same phyla, and label the critical innovations.
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BIOLOGY
- You take a field trip to tide pools in Puget Sound and encounter all sorts of Animals. Please use the following descriptions of those adult Animals to determine which of the 9 major phyla each belongs. Has radial symmetry and two tissue layers: ["cnidaria", "Mollusca", "Arthropoda", "Annelida", "Platyhelminthes", "Porifera"] Has 6 jointed appendages and a chitinous exoskeleton: ["cnidaria", "Mollusca", "Arthropoda", "Annelida", "Platyhelminthes", "Porifera"] Has bilateral symmetry with a digestive sac and no coelom: ["cnidaria", "Mollusca", "Arthropoda", "Nematoda", "Platyhelminthes", "Porifera"] Has bilateral symmetry, an open circulatory system, a digestive tube, gills and a radula: ["cnidaria", "Mollusca", "Arthropoda", "Nematoda", "Platyhelminthes", "Porifera"] Has no true tissues and no body symmetry: ["cnidaria", "Mollusca", "Arthropoda", "Nematoda", "Platyhelminthes", "Porifera"]arrow_forwardImagine you come across a small worm. How can you determine whether it is a class Hirudinida or a turbellarian? Give two distinct differences between the two without naming the same structure/invisible features of each animal (e.g animal x has 2 wings, animal y has 4 wings are not distinct differences)arrow_forwardThe phylogenetic tree in Exercise 1 above shows an outdated relationship between Brachiopoda, Bryozoa, and Mollusca. We now know that: (1) Brachiopoda is more closely related to Mollusca; and (2) Bryozoa forms the sister-group to the clade formed by Brachiopoda+Mollusca. In the space below draw a phylogenetic tree showing the correct interrelationships among the 5 clades listed: Bryozoa: Brachiopoda: Linguliformea: Craniiformea: Rhynchonelliformea: Please include mollusca. Should be 6 classes totalarrow_forward
- The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of (A) a body cavity. (B) a complete digestive tract. (C) mesoderm. (D) tissues.arrow_forwardMollusca (clams, abalone, nudibranchs, snails, squid, octopi, etc). Unifying features include shell, mantle, radula, foot, visceral mass Which classes show a loss of the shell. How does the shell benefit an organism, how does the loss of the shell benefit other members of this phylum? Distinguish between polyplacophora, bivalva, gastropoda, and chephalopoda We see the first evolution of a true eye here. Who has it? What are chromatophores? How doe members of this group use them? What other unique defense addaptaions do we see in this group? (warning colors, 2 shells, ink)arrow_forwardClass Gastropoda and Class Bivalvia independently evolved modifications to their body plan that allowed them to invade sandy and muddy habitats, burying their bodies under the surface and accessing the surface via siphons. For an example organism in each Class, (1) draw a diagram showing the morphological modifications and (2) write a description of how this organism had evolved from the hypothetical ancestral mollusk (HAM) body plan.arrow_forward
- Give at least (3) body structures that are salient among these groups of animals: Protozoans Poriferan Cnidariansarrow_forwardIn the different lineages of molluscs, it is easy to understand the variations from the basic organizational plan in relation to the lifestyles of the organisms. For example, the clam is a buried living organism that feeds by filtration and the cuttlefish is a free predatory organism. The organization of Lamellibranchs and Cephalopods can then be related to these lifestyles.Based on the texts provided, the various illustrations and your knowledge, indicate in a short text :Adaptations to filtration in clams (and by extension in lamellibranchs)arrow_forwardWhich of the following statements is CORRECT? Eumetazoans lack true tissues Cnidarians have three germ layers Animals evolved from an ancestral protist Sponges belong the clade called Eumetazoaarrow_forward
- Rotifers and acanthocephalans previously belonged to separate phylum. But recent molecular studies and genome analysis show that acanthocephalans are sister groups of a class under Phylum Rotifera. And thus, the two should belong to a single taxon. Aside from the molecular evidences, what morphological and physiological features of both the rotifers and acanthocephalans support this claim? Explain your answer.arrow_forwardWhich of the following structures would be found in the mesohyl of a sponge? amoebocytes and choanocytes amoebocytes and spicules spicules and choạnocytes amoebocytes and polypsarrow_forwardCreate a body plan table (Insert → Add Table) for the following animal phyla: Porifera, Cnidaria, Platyhelminthes, Mollusca, Annelida, Nematoda, Arthropoda, Echinodermata, and Chordata. Describe each phylum by identifying the following body plan features. Use Lesson 12 (Chapter 32) and Lesson 13 (Chapter 33) as a guide. 1) Symmetry: Asymmetrical, Radial, or Bilateral 2) Tissue type: Parazoa, Eumetazoa (diploblastic), or Eumetazoa (triploblastic) 3) Body cavity (if triploblastic): Acoelomate, Psuedocoelomate, or Coelomate 4) Developmental mode (if Coelomate): Protostome or Dueuterostome Note: Depending on the body plan, features 3 & 4 may not apply to specific phyla. * Please answer 3) and 4) ONLY. Thank you.arrow_forward
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