Textbook Question
Which synapomorphy (shared, derived trait) distinguishes animals as a monophyletic group, distinct from choanoflagellates?
a. Multicellularity
b. Coloniality
c. Heterotrophy
d. Movement
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Ch. 30 - An Introduction to Animals
Freeman7th EditionBiological ScienceISBN: 9783584863285
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Table of contents
- Ch. 1 - Biology: The Study of Life11
- Ch. 2 - Water and Carbon: The Chemical Basis of Life10
- Ch.3 - Protein Structure and Function11
- Ch.4 - Nucleic Acids and the RNA World10
- Ch. 5 - An Introduction to Carbohydrates10
- Ch. 6 - Lipids, Membranes, and the First Cells10
- Ch. 7 - Inside the Cell10
- Ch. 8 - Energy and Enzymes: An Introduction to Metabolism10
- Ch. 9 - Cellular Respiration and Fermentation16
- Ch. 10 - Photosynthesis14
- Ch. 11 - Cell-Cell Interactions14
- Ch. 12 - The Cell Cycle12
- Ch. 13 - Meiosis13
- Ch. 14 - Mendel and the Gene32
- Ch. 15 - DNA and the Gene: Synthesis and Repair8
- Ch. 16 - How Genes Work35
- Ch. 17 - Transcription, RNA Processing, and Translation16
- Ch. 18 - Control of Gene Expression in Bacteria19
- Ch. 19 - Control of Gene Expression in Eukaryotes17
- Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers23
- Ch. 21 - Genes, Development, and Evolution13
- Ch. 22 - Evolution by Natural Selection17
- Ch. 23 - Evolutionary Processes13
- Ch. 24 - Speciation15
- Ch. 25 - Phylogenies and the History of Life13
- Ch. 26 - Bacteria and Archaea17
- Ch. 27 - Diversification of Eukaryotes19
- Ch. 28 - Green Algae and Land Plants18
- Ch. 29 - Fungi19
- Ch. 30 - An Introduction to Animals9
- Ch. 31 - Protostome Animals20
- Ch. 32 - Deuterostome Animals19
- Ch. 33 - Viruses16
- Ch. 34 - Plant Form and Function16
- Ch. 35 - Water and Sugar Transport in Plants16
- Ch. 36 - Plant Nutrition13
- Ch. 37 - Plant Sensory Systems, Signals, and Responses16
- Ch. 38 - Flowering Plant Reproduction and Development16
- Ch. 39 - Animal Form and Function16
- Ch. 40 - Water and Electrolyte Balance in Animals16
- Ch. 41 - Animal Nutrition16
- Ch. 42 - Gas Exchange and Circulation16
- Ch. 43 - Animal Nervous Systems16
- Ch. 44 - Animal Sensory Systems16
- Ch. 45 - Animal Movement11
- Ch. 46 - Chemical Signals in Animals16
- Ch. 47 - Animal Reproduction and Development18
- Ch. 48 - The Immune System in Animals16
- Ch. 49 - An Introduction to Ecology16
- Ch. 50 - Behavioral Ecology16
- Ch. 51 - Population Ecology16
- Ch. 52 - Community Ecology20
- Ch. 53 - Ecosystems and Global Ecology16
- Ch. 54 - Biodiversity and Conservation Ecology16
Chapter 30, Problem 4
Which of these characteristics does not apply to cnidarians?
a. Are diploblastic
b. Possess a gastrovascular cavity with one opening
c. Undergo metamorphosis
d. Have a central nervous system
Verified step by step guidance1
Understand the characteristics of cnidarians: Cnidarians are a group of animals that include jellyfish, corals, and sea anemones. They are known for their radial symmetry, diploblastic tissue organization (having two germ layers: ectoderm and endoderm), and a gastrovascular cavity with a single opening that serves as both mouth and anus.
Review the term 'diploblastic': Diploblastic organisms develop from two primary germ layers during embryonic development. This is a defining feature of cnidarians, so option 'a' applies to them.
Examine the gastrovascular cavity: Cnidarians possess a gastrovascular cavity with one opening, which is used for both ingestion and excretion. This characteristic matches option 'b'.
Analyze metamorphosis: Some cnidarians, such as jellyfish, undergo metamorphosis during their life cycle, transitioning from a polyp stage to a medusa stage. This means option 'c' applies to them.
Consider the central nervous system: Cnidarians do not have a central nervous system. Instead, they have a decentralized nerve net that coordinates their movements and responses. Therefore, option 'd' does not apply to cnidarians.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cnidarian Characteristics
Cnidarians are a group of animals that include jellyfish, corals, and sea anemones. They are characterized by their radial symmetry, presence of specialized cells called cnidocytes for capturing prey, and a simple body plan that includes a gastrovascular cavity. This cavity serves both digestive and circulatory functions, allowing for the distribution of nutrients throughout the organism.
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Characteristics of Life
Diploblastic Organization
Diploblastic organisms, like cnidarians, develop from two primary germ layers: the ectoderm and endoderm. This contrasts with triploblastic organisms, which have a third layer called the mesoderm. The diploblastic structure contributes to the simpler body organization of cnidarians, influencing their physiological functions and overall morphology.
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Nervous System in Cnidarians
Cnidarians possess a decentralized nerve net rather than a central nervous system. This nerve net allows for basic responses to environmental stimuli, but it lacks the complexity found in organisms with a central nervous system. As a result, cnidarians do not exhibit behaviors associated with higher nervous systems, such as learning or complex movement patterns.
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Related Practice
Textbook Question
In a tube-within-a-tube body plan, what is the interior tube derived from?
a. Ectoderm
b. Mesoderm
c. The coelom
d. Endoderm
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Textbook Question
True or false?
New major animal body plans have continued to evolve since the Cambrian about 550 million years ago.
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Textbook Question
Why is it ecologically significant that animals are heterotrophic and multicellular?
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Textbook Question
To estimate the relative abundance of the major phyla, calculate how many named species of arthropods, mollusks, and nematode worms exist per named species of chordate (the phylum containing vertebrates, including humans; see Table 30.1).
Do you think these calculations are likely to be underestimates or overestimates? Why?
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Textbook Question
Evaluate this statement: Animals evolved from simple to complex.
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