Applied Biology - Earthworm Anatomy

Questions and Answers

What is a crop?

Digestive system sac in which earthworms store ingested soil.

What is the function of the gizzard?

Grinds up food.

What are nephridia?

Excretory structures in earthworms in each body segment.

What do seminal vesicles do?

Secrete a fluid rich in sugar that nourishes and helps sperm move. Signup and view all the answers

What is the role of seminal receptacles?

Receive sperm from another worm. Signup and view all the answers

What is the prostomium?

Liplike covering over the mouth of the worm. Signup and view all the answers

What is the clitellum?

Band of thickened, specialized segments in annelids that secretes a mucus ring. Signup and view all the answers

What is the function of a cuticle?

Protects the organism and keeps it moist. Signup and view all the answers

What are setae?

Bristle-like structures that help segmented worms move. Signup and view all the answers

What are aortic arches?

Heart-like pumping organs of earthworms. Signup and view all the answers

What is the function of the pharynx?

A common passageway for solid food, liquids, and air. Signup and view all the answers

What does the dorsal blood vessel do?

Carries blood toward the head of the earthworm. Signup and view all the answers

What is the ventral nerve cord?

Carries nerve impulses. Signup and view all the answers

What is a closed circulatory system?

A circulatory system in which blood moves only within a connected network of tubes called blood vessels. Signup and view all the answers

What is an open circulatory system?

A circulatory system that allows blood to flow out of the blood vessels and into various body cavities. Signup and view all the answers

What is internal fertilization?

Type of fertilization that occurs when sperm and egg combine inside an animal's body. Signup and view all the answers

What is external fertilization?

Eggs shed by the female are fertilized by sperm in the external environment. Signup and view all the answers

What does anterior mean?

Toward the front. Signup and view all the answers

What does posterior mean?

Toward the back. Signup and view all the answers

How do earthworms mate?

Two worms line up inverted from each other to exchange sperm. Signup and view all the answers

What is unique about the worm circulatory system?

Earthworms have a closed circulatory system that circulates blood exclusively through vessels. Signup and view all the answers

How do earthworms respirate?

They breathe through their skin. Signup and view all the answers

Study Notes

Digestive System

Crop: A sac in the digestive system of earthworms for storing ingested soil.
Gizzard: A thick muscular organ found in birds, earthworms, and grasshoppers that grinds food.
Pharynx: A passageway for solid food, liquids, and air within the digestive tract.

Excretory and Reproductive Structures

Nephridia: Excretory structures located in each body segment of earthworms.
Seminal Vesicles: Two glands that secrete a sugar-rich fluid to nourish and aid sperm movement.
Seminal Receptacles: Structures that receive sperm from another earthworm.
Clitellum: Specialized band that secretes a mucus ring for egg and sperm release during reproduction.

Body Coverings and Movement

Cuticle: A tough, flexible protective covering that keeps the organism moist.
Setae: Bristle-like structures that assist segmented worms in movement.

Circulatory System

Aortic Arches: Heart-like organs in earthworms responsible for pumping blood.
Dorsal Blood Vessel: Carries blood toward the head of the earthworm.
Ventral Blood Vessel: Carries blood toward the tail end of the worm.
Closed Circulatory System: Blood circulates only within blood vessels, found in earthworms and humans.

Respiratory System

Earthworms lack lungs and respire through their skin via diffusion of oxygen and carbon dioxide, requiring moist skin.
They release body fluids and mucus to keep skin damp and typically surface at night to reduce evaporation.

Fertilization and Reproduction

Earthworms are hermaphroditic, possessing both male and female reproductive organs.
They require a mate for reproduction, exchanging sperm during mating.
Eggs are stored and fertilized within a cloacal tube before being deposited in the soil as cocoons.

Anatomical Orientation

Anterior: Refers to the front side of the earthworm.
Posterior: Refers to the back side of the earthworm.

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Test your knowledge on the anatomy of earthworms with this set of flashcards. Each card provides a key term such as 'crop' and 'gizzard,' along with their definitions related to the earthworm's digestive and excretory systems. Perfect for students of applied biology!