Earthworm Anatomy and Reproduction

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Questions and Answers

What makes an organism an invertebrate?

No backbone

Why are earthworms classified as annelids?

They have rings or segments that make their bodies

External segments of annelids are called?

Metameres

Where is the mouth located in an earthworm?

Anterior Signup and view all the answers

Where is the anus located in an earthworm?

Posterior Signup and view all the answers

What are septa and where are they located?

Dividing walls between segments Signup and view all the answers

Are earthworms segmented internally?

True Signup and view all the answers

Name the internal cross walls that separate the inside of an earthworm.

Septa Signup and view all the answers

What is the swollen band around the worm and what is its purpose?

Clitellum, reproduction Signup and view all the answers

What is the 'lip' called and what is its function?

It's called the prostomium and it's used to dig through soil. Signup and view all the answers

What are setae and where are they located?

They are bristles on the underside of an earthworm, located between segments. Signup and view all the answers

What is the function of setae?

Help it move Signup and view all the answers

At what segment do the reproductive structures start?

9 Signup and view all the answers

What are seminal receptacles?

Where sperm from another worm is stored, located in segments 9 & 10. Signup and view all the answers

What are seminal vesicles?

Where testes are located, located in segments 9-12. Signup and view all the answers

What are ovaries?

Where eggs are produced, located in segment 13. Signup and view all the answers

What are testes?

Where sperm is produced, located in seminal vesicles and segments 9-12. Signup and view all the answers

Describe earthworm mating.

Sperm from one worm travels along the sperm grooves to the seminal receptacles of another worm. Fertilization takes place outside of the body. They are hermaphrodites. Signup and view all the answers

Why are earthworms hermaphrodites?

They produce both eggs and sperm. Signup and view all the answers

What are the hearts called?

Aortic arches Signup and view all the answers

How many hearts does an earthworm have?

5 Signup and view all the answers

What are the two major blood vessels in earthworms?

Ventral blood vessel and dorsal blood vessel Signup and view all the answers

Is circulation in earthworms open or closed? Why?

False Signup and view all the answers

Name the parts of an earthworm's digestive tract in order beginning with the mouth.

It goes from mouth to pharynx to esophagus to the crop to the gizzard to the intestine through the rectum and anus. Signup and view all the answers

What is the mouth in the context of an earthworm?

Beginning of the digestive tract Signup and view all the answers

What does the pharynx do?

Floods through this Signup and view all the answers

What is the function of the esophagus?

Acts as a passageway between the pharynx and crop. Signup and view all the answers

What is the purpose of the crop?

Stores food temporarily Signup and view all the answers

What is the function of the gizzard?

Holds the ground up mixture Signup and view all the answers

What does the intestine do?

Digests and absorbs the mixture Signup and view all the answers

What is the anus in the context of an earthworm?

Used to pass out the mixture Signup and view all the answers

What are ganglia?

Masses of tissue containing many nerve cells Signup and view all the answers

Earthworms respond to ___________ from their environment.

Nerve impulses Signup and view all the answers

What is the job of the excretory system?

It eliminates wastes produced by homeostasis. Signup and view all the answers

What are nephridia?

Tiny white fibers that carry out excretory functions Signup and view all the answers

Where are nephridia found in an earthworm?

On the dorsal body wall Signup and view all the answers

What gas do earthworms need to live?

Oxygen Signup and view all the answers

How do earthworms obtain their oxygen?

From the skin. The gases are exchanged between the circulatory system and the environment. Signup and view all the answers

Do earthworms fertilize their own eggs?

False Signup and view all the answers

What are the three main parts of the earthworm's nervous system?

Ventral nerve cord, brain, ganglia Signup and view all the answers

What is the purpose of a cocoon in earthworms?

A clitellum/egg capsule holds female eggs Signup and view all the answers

What is the difference between seminal receptacles and seminal vesicles in earthworms?

Seminal receptacles store sperm, while seminal vesicles contain testes. Signup and view all the answers

Study Notes

Earthworms Overview

Earthworms are invertebrates, meaning they lack a backbone.
Classified as annelids due to their segmented body structure featuring rings called metameres.

Body Structure

Anterior end is where the mouth is located; the posterior end houses the anus.
Septa are the internal dividing walls found between segments of the worm.
Earthworms exhibit internal segmentation, reinforced by the presence of septa.
Setae are bristles located on the underside, present between segments, aiding in movement.

Reproductive Features

The clitellum is a swollen band vital for reproduction, indicating readiness to mate.
The prostomium, a liplike structure, assists in soil excavation.
Reproductive structures emerge from segment 9, including seminal receptacles (segments 9 and 10) for storing sperm, and seminal vesicles (segments 9-12) where testes are located.
Ovaries in segment 13 produce eggs.
Earthworms are hermaphrodites, producing both eggs and sperm; fertilization happens externally.

Circulatory System

Earthworms have five aortic arches, functioning as hearts.
Circulatory system is closed, meaning blood is contained within vessels.

Digestive System

The digestive tract includes: mouth → pharynx → esophagus → crop (temporary food storage) → gizzard (breaks down food) → intestine (digestion and absorption) → rectum → anus (excretes waste).
Anus facilitates the passage of undigested material.

Nervous System

Composed of a ventral nerve cord, brain, and ganglia (masses of nerve cells).
Earthworms respond to environmental stimuli via nerve impulses.

Excretory System

Eliminates metabolic wastes through nephridia, tiny white structures located on the dorsal body wall, performing excretory functions.
Ensures homeostasis within the organism.

Respiration

Earthworms require oxygen for survival, obtained through skin respiration where gases are exchanged with the environment.

Miscellaneous

Earthworms do not fertilize their own eggs; they require a partner for reproduction.
A cocoon serves as a protective capsule for female eggs, created by the clitellum during reproduction.

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Description

Explore the fascinating world of earthworms, invertebrate annelids known for their unique segmented bodies. This quiz covers their body structure, reproductive features, and key anatomical components like the clitellum and setae. Test your knowledge on these important soil organisms!