Questions and Answers
What is the function of the anus in a starfish?
Where is the mouth located in relation to the anus in a starfish?
What is the role of the stomach in a starfish?
What surrounds the stomach in a starfish?
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What structure extends from the ring canal into the starfish's arms?
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What attaches to the radial canal in a starfish?
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Where are digestive glands located in a starfish?
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What does echinoderm mean?
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Do echinoderms have a brain or a nervous system?
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How do echinoderms move?
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Which echinoderm is globular in shape?
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Which echinoderm can eject part of its intestines?
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What do starfish eat?
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What surrounds the mouth of sea cucumbers?
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Why are starfish said to have pentaradial symmetry?
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What is Aristotle's lantern and what echinoderm has this structure?
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On which surface is the mouth usually found in echinoderms?
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What is a 'test' in the context of echinoderms?
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What is unusual about the spines of sea urchins?
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What helps move food toward the mouth of sea urchins?
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How do sea cucumbers move?
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How does a sea cucumber breathe?
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What makes up the skin of sand dollars?
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Where do sand dollars live?
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Study Notes
Anatomy of a Starfish
- The anus of a starfish is located on top, serving as the waste exit point.
- The mouth, positioned opposite the anus, is the entry point for food.
- The stomach is centrally located between the mouth and anus, where food digestion occurs.
- Surrounding the stomach is the ring canal, an integral part of the starfish's water vascular system.
- Radial canals extend from the ring canal into the starfish's arms, facilitating movement and water circulation.
- Tiny tube feet with suckers are attached to the radial canals, aiding in locomotion and feeding.
- Digestive glands reside within the starfish's arms, releasing chemicals to help break down food.
Echinoderms Overview
- Echinoderm translates to "spiny-skinned invertebrates" that inhabit ocean floors.
- Echinoderms lack brains and traditional nervous systems, relying instead on a decentralized nerve net.
- Movement in echinoderms is achieved through their water vascular system.
Specific Echinoderms
- Sea urchins are characterized by their globular shape.
- Sea cucumbers have the unique ability to eject parts of their intestines as a defense mechanism.
- Starfish primarily feed on mollusks and other small marine animals.
Physical Features
- Sea cucumbers are surrounded by 8-30 tentacles, modified tube feet, which assist in feeding.
- Starfish exhibit pentaradial symmetry, meaning their bodies are arranged in five or more radiating parts.
- Aristotle's lantern is a specialized feeding structure found in sea urchins.
Additional Facts
- The mouth of echinoderms is typically located on the oral surface, facilitating feeding.
- A "test" refers to the hard shell or exoskeleton of sea urchins, providing protection.
- Sea urchin spines are known for their unusual, hardened structure, aiding in defense.
- Food grooves, or podia, help move food toward the mouth of sea urchins.
- Sea cucumbers move using five double rows of tube feet.
- Breathing in sea cucumbers occurs by pumping seawater in and out of an internal organ called the respiratory tree.
- Sand dollars possess a flattened disk structure and reside on the sandy sea floor, from the intertidal zone to the subtidal zone.
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Test your knowledge on the anatomy of starfish and other echinoderms with these flashcards. Each card covers key terms and their definitions. Perfect for students looking to deepen their understanding of marine biology.
