Podcast
Questions and Answers
Identify 4 general examples of echinoderms.
Sea stars, sand dollars, sea urchins, sea cucumbers
Differentiate the symmetry of adult echinoderms from that of their larvae stage.
Adults are radially symmetrical; larvae are bilaterally symmetrical
Were early echinoderms able to move as adults?
False
Because of adults being sessile, what evolved as a result?
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How many species of echinoderms are still sessile?
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What characteristic makes echinoderms different from all other invertebrates?
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Are echinoderms more closely related to us or other invertebrates? Justify your answer.
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Identify the four major characteristics of echinoderms.
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What is the meaning of the name Crinoidea?
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What is the meaning of the name Ophiuroidea?
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What is the meaning of the name Echinoidea?
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What is the meaning of the name Holothuroidea?
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What is the meaning of the name Asteroidea?
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Name examples of echinoderms in class Crinoidea.
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Name examples of echinoderms in class Ophiuroidea.
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Name examples of echinoderms in class Echinoidea.
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Name an example of an echinoderm in class Holothuroidea.
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Name an example of an echinoderm in class Asteroidea.
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Trace the flow of water through the Water-vascular system (WVS).
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What are general characteristics of class Asteroidea?
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How do podia operate?
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Which one is bigger, the cardiac or the pyloric stomach?
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Explain the nutrition of organisms in class Asteroidea.
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What are additional characteristics of class Asteroidea?
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What are general characteristics of class Echinoidea?
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Study Notes
General Echinodermata Characteristics
- Examples include sea stars, sand dollars, sea urchins, and sea cucumbers.
- Adult echinoderms exhibit radial symmetry, while larvae are bilaterally symmetrical.
- Early echinoderms were sessile as adults, which led to the development of radial symmetry.
- Approximately 80 species of echinoderms remain sessile today.
- Unique characteristic: echinoderms are deuterostomes, linking them more closely to vertebrates than to other invertebrates.
Major Echinodermata Features
- Four key characteristics:
- Pentaradial symmetry, where body parts extend from the center along five spokes.
- Ossicles, the calcium carbonate plates forming the endoskeleton, sometimes protruding through the skin.
- Water-vascular system, a network of water-filled canals aiding locomotion and feeding.
- Tube feet, small extensions for movement, feeding, respiration, and excretion.
Echinoderm Diversity
- Total number of echinoderm species is around 7,000.
- Five major classes of echinoderms:
- Crinoidea (e.g., sea lilies, feather stars) - meaning “lily-like”
- Ophiuroidea (e.g., basket stars, brittle stars) - meaning “snake-like”
- Echinoidea (e.g., sea urchins, sand dollars) - meaning “spine-like”
- Holothuroidea (e.g., sea cucumbers) - meaning “water polyp”
- Asteroidea (e.g., sea stars) - meaning “starlike”
Water-Vascular System (WVS)
- Water circulates through the WVS via the following path: madreporite → stone canal → ring canal → radial canal → lateral canal → ampullae → tube feet.
Class Asteroidea Characteristics
- Typically possess five arms merging with a central disk.
- The mouth is located on the central oral surface facing downward.
- Podia operate by fluid movement: the ampulla contracts, extending the podia. Suckers grip the substrate, the podia then retract, pulling the body forward.
- Nutrition involves a two-part stomach system: cardiac (larger) and pyloric, leading to digestive glands in each arm.
Additional Class Asteroidea Features
- Endoskeleton comprises calcareous plates (ossicles) and spines, with gas exchange facilitated by papulae.
- Pedicellariae serve as jaw-like appendages for various functions.
General Class Echinoidea Characteristics
- Members lack arms and exhibit a rounded body shape.
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Description
Test your knowledge about Phylum Echinodermata with these flashcards. You'll explore various echinoderm species, their symmetry, and historical movement patterns. Perfect for students studying marine biology or zoology.