Questions and Answers
What role does the madreporite play in the water vascular system of sea stars?
Pressure regulation and simple filter
Does the sea star possess a heart or circulatory system? How do you suppose nutrients and oxygen are distributed to the body tissues?
Internal water canals branching from a central ring canal; O2 & nutrients are distributed via water pumped throughout
Does the sea star possess an excretory system? How do you suppose metabolic wastes are eliminated from the body?
No excretory system; Mostly excretes uric acid and waste via diffusion through tube feet
Why are ossicles classified as an endoskeleton?
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How do sea cucumbers defend themselves given their loss of sharp spines?
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What characteristics do sea cucumbers possess that would cause zoologists to group them in the same phylum with other echinoderms?
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Why are chordates and echinoderms similar?
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What are the advantages of an endoskeleton?
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What is unique about the madreporite of sea cucumbers (class Holothuroidea)?
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What is the class of Asterias?
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What is the class of sea lilies and feather stars?
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What is the class of sea cucumbers?
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What is the class of brittle stars?
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What is the class of soft, cylindrical body with leathery skin?
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What is the class of body containing a stalk with mouth and anus on the oral surface?
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What is the class of body plates fused into a solid test with long, movable spines?
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What is the phylum and class for a starfish?
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What are the main components of sea cucumber anatomy?
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What is the function of sea star spines?
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What is the function of sea star pedicellariae?
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What is the function of sea star dermal branchiae?
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What is the function of the sea star mouth?
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What is the function of the sea star madreporite?
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What is the function of the sea star ambulacral grooves?
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What is the function of sea star tube feet?
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What is the function of the sea star cardiac stomach?
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What is the function of the sea star pyloric stomach?
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What is the function of sea star digestive glands?
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What is the function of sea star rectal ceca?
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What is the function of sea star gonads?
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What is the function of the sea star ring canal?
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What is the function of sea star radial canals?
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What is the function of sea star ampullae?
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What is the function of sea cucumber tentacles?
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What is the function of the sea cucumber ring canal?
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What is the function of sea cucumber ampullae?
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What is the function of the sea cucumber pharynx?
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What is the function of the sea cucumber madreporite?
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What is the function of the sea cucumber cloaca?
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What is the function of the sea cucumber anus?
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Study Notes
Echinoderms Overview
- Echinoderms include diverse marine species with a water vascular system, uniquely adapted for movement and feeding.
- Key classes include Asteroidea (sea stars), Crinoidea (sea lilies), Holothuroidea (sea cucumbers), Ophiuroidea (brittle stars), and Echinoidea (sea urchins).
Madreporite
- Serves as a pressure regulator and filter within the water vascular system.
- In sea cucumbers, it lies freely in the coelom, differing from its fixed position in other echinoderms.
Circulatory System
- Echinoderms lack a traditional heart and circulatory system.
- Nutrients and oxygen are distributed through internal water canals connected to a central ring canal, using hydraulic pressure.
Excretory System
- Echinoderms lack a distinct excretory system.
- Metabolic wastes are primarily excreted through diffusion via tube feet.
Endoskeleton and Ossicles
- Ossicles are hard structures that form an internal endoskeleton, providing support while allowing for growth.
- The water vascular system and pentaradial symmetry unite echinoderms, including sea cucumbers.
Defense Mechanisms
- Sea cucumbers defend themselves through evisceration, expelling water and internal organs to escape predators.
Sea Star Anatomy
- Features include a mouth leading to a cardiac stomach, equipped with tube feet for locomotion and prey capture.
- The pyloric stomach receives digestive secretions for further digestion.
- Gonads produce gametes for reproduction; the rectal ceca enhance nutrient absorption.
Functions of Various Structures
- Pedicellariae: Pincer-like structures that eliminate small organisms from the surface, keeping skin free of parasites.
- Dermal Branchiae: Facilitate gas exchange and waste excretion through diffusion.
- Ampullae: Provide hydraulic pressure, enabling movement of tube feet.
Sea Cucumber Anatomy
- Characterized by a mouth, pharynx (food transport), intestines, gonad, and a cloaca for ventilating seawater.
- Tube feet movement is supported by hydraulic pressure provided by ampullae.
Reproductive Structures
- Gonads generate gametes, influencing reproduction, demonstrating variations in sexual reproduction methods across echinoderm classes.
Summary of Classes
- Asteroidea: Sea stars; recognized for their multiple arms and retractable stomachs.
- Crinoidea: Sea lilies and feather stars; possess a stalk and mouth/anus orientation on the oral surface.
- Holothuroidea: Sea cucumbers; have a soft body and specialized tentacles for feeding.
- Ophiuroidea: Brittle stars; known for their brittle arms and small size.
- Echinoidea: Sea urchins; body plates fused into a solid test with movable spines.
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Description
Test your knowledge on the water vascular system of echinoderms, particularly sea stars. This quiz covers various aspects such as the role of the madreporite and the distribution of nutrients and oxygen. Perfect for students studying marine biology or related subjects!