Questions and Answers
What makes an organism an invertebrate?
no backbone
Why are earthworms classified as annelids?
rings or segments make up their bodies
External segments of annelids are called ____
metameres
The mouth is at the ____ end and the anus is at the ____ end.
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What are setae and where are they located?
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What is the function of setae?
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Are earthworms segmented internally?
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Name the internal cross-walls that separate the inside of an earthworm.
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What is the swollen band around the earthworm called and what is its purpose?
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At what segment do the reproductive structures start?
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Tell the location and function of seminal receptacles.
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Tell the location and function of seminal vesicles.
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Tell the location and function of ovaries.
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Tell the location and function of testes.
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Describe earthworm mating.
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Why are earthworms hermaphrodites?
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What are the hearts called and how many do earthworms have?
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Name two major blood vessels in earthworms.
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Is circulation in earthworms open?
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Name the parts of an earthworm's digestive tract in order beginning with the mouth.
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What is the function of the mouth in the digestive tract?
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What is the function of the pharynx in the digestive tract?
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What is the function of the esophagus in the digestive tract?
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What is the function of the crop in the digestive tract?
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What is the function of the gizzard in the digestive tract?
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What is the function of the intestines in the digestive tract?
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What is the function of the anus in the digestive tract?
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Name the three main parts of the earthworm's nervous system.
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What are ganglia?
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Do other animals have ganglia?
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Earthworms, like all animals, respond to ____ from their environment.
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What is the job of the excretory system in an animal?
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What are nephridia and where are they found in the earthworm?
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What gas do earthworms need to live?
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How do earthworms obtain their oxygen?
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Study Notes
Annelida Overview
- Invertebrates lack a backbone, defining a major group of animals including annelids.
- Earthworms are classified as annelids due to their segmented body structure known as metameres.
Structural Features
- Earthworms exhibit an anterior end (mouth) and a posterior end (anus).
- Setae, or bristle-like structures located on the underside, assist in locomotion.
- An adult earthworm has over 100 internal segments, contributing to its segmentation.
- Internal cross-walls called septa divide the body cavities of earthworms.
Reproductive Anatomy
- The clitellum, a swollen band on sexually mature worms, is vital for cocoon formation.
- Reproductive structures:
- Seminal Receptacles: Located in segments 9 and 10; store sperm from other worms.
- Seminal Vesicles: Found in segments 9-12; produce sperm within testes.
- Ovaries: Located in segment 13; site of egg production.
- Testes: Also in segment 13; responsible for sperm production.
Reproductive Process
- Earthworms are hermaphrodites, producing both eggs and sperm.
- Mating involves the transfer of sperm along sperm grooves to seminal receptacles of another worm, with external fertilization occurring in the cocoon.
Circulatory System
- Earthworms have five aortic arches, often referred to as hearts.
- Key blood vessels include the ventral and dorsal blood vessels.
- They possess a closed circulatory system, with blood contained within vessels at all times.
Digestive System
- The digestive tract includes: mouth, pharynx, esophagus, crop, gizzard, intestines, and anus, functioning sequentially for nutrient processing.
- The mouth ingests soil and organic matter, while the pharynx initiates digestion.
- The esophagus serves as a passageway, and the crop temporarily stores food.
- The gizzard grinds the mixture, whereas digestion and absorption occur in the intestines.
- Undigested material and soil particles are expelled through the anus.
Nervous System
- The earthworm's nervous system consists of a ventral nerve cord, a brain, and ganglia.
- Ganglia are clusters of nerve cell masses, present in other animals as well.
Sensory Response
- Earthworms respond to environmental stimuli, integral for survival.
Excretory System
- The excretory system eliminates waste products from metabolic processes.
- Nephridia, found in pairs in each body segment, carry out excretory functions.
Respiration
- Earthworms require oxygen for survival, which they absorb through their skin by diffusion.
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Description
Test your knowledge on Annelida with these flashcards! This quiz covers key definitions, classifications, and anatomical features of earthworms and other segmented worms. Perfect for students studying biology or focusing on invertebrate zoology.
