Questions and Answers
What does 'monoecious' mean?
What is the prostomium?
That part of the head located in front of the mouth.
Where is the mouth located in an earthworm?
Just behind the prostomium.
What are segments in relation to the body structure?
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What is the function of the clitellum in earthworms?
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What are cerebral ganglia?
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What is the role of the subpharyngeal ganglion?
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What is the pharynx?
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What is the esophagus in earthworms?
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What do aortic arches do?
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What is the role of calciferous glands?
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What are seminal receptacles?
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What is the function of seminal vesicles?
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What is the role of testes in earthworms?
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What do ovaries do in earthworms?
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What is an oviduct?
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What is the function of the crop in an earthworm?
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What is the gizzard?
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What does the dorsal vessel do?
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What is the ventral nerve cord?
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What is the function of lateral nerves?
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What is the role of the intestine in earthworms?
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What is a septum?
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What is a nephridium?
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How do body segments react when longitudinal muscles contract?
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How do body segments react when circular muscles contract?
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What is the most obvious difference between clamworms and earthworms?
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Know the excretory system and nervous system of an earthworm.
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Study Notes
Annelida Class Oligochaeta: Earthworm Overview
- Earthworms are monoecious, meaning each individual possesses both male and female reproductive organs.
- The prostomium is the head segment located in front of the mouth in annelids.
Anatomy and Digestion
- The mouth is positioned just behind the prostomium and serves as the intake for food.
- Earthworm bodies are made up of multiple segments, each functioning as a distinct unit.
- The pharynx connects the mouth to the esophagus, serving as a passageway for food.
- The esophagus is a muscular tube that transports food to the crop.
- The crop serves as a storage area for food before it moves to the gizzard.
- The gizzard is a modified stomach that grinds food with the help of stones.
Circulatory System
- Aortic arches act as a primitive heart, with five pairs pumping blood into dorsal and ventral vessels.
- The dorsal vessel runs along the worm's back, transporting blood toward the anterior end.
Nervous System
- Cerebral ganglia function as a rudimentary brain; they extend into paired ventral nerve cords.
- The subpharyngeal ganglion acts as a connection beneath the pharynx, part of the ventral nervous system.
Reproductive Structures
- The clitellum is a thickened, saddle-like structure involved in reproduction, secreting a sac for egg storage.
- Seminal receptacles store sperm received from other worms, while seminal vesicles produce seminal fluid.
- Testes produce sperm, and ovaries are responsible for egg production and maturation.
Excretory System
- Nephridia are paired excretory tubules that help in waste elimination and osmoregulation.
- Calciferous glands in the esophagus excrete excess calcium for elimination through feces.
Muscular System Functionality
- Longitudinal muscle contractions shorten the body, while circular muscle contractions narrow the diameter.
Comparative Anatomy
- Oligochaetes like earthworms have few chaetae (bristles), contrasting with the many chaetae found in polychaetes such as clamworms.
- Both groups differ in reproductive structures; oligochaetes are hermaphroditic and possess a clitellum.
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Description
Test your knowledge on the Earthworm's anatomy and characteristics through these flashcards focusing on the Oligochaeta class of annelids. Learn definitions of key terms such as 'monoecious' and 'prostomium' to enhance your understanding of these fascinating organisms.