Annelida Flashcards
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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.

<p>anterior and posterior</p> Signup and view all the answers

What are setae and where are they located?

<p>they are on the underside of the earthworm (bristles)</p> Signup and view all the answers

What is the function of setae?

<p>they help the earthworm move</p> Signup and view all the answers

Are earthworms segmented internally?

<p>True</p> Signup and view all the answers

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

<p>septa</p> Signup and view all the answers

What is the swollen band around the earthworm called and what is its purpose?

<p>the clitellum - found on sexually mature worms and is active in the formation of an egg capsule, or cocoon</p> Signup and view all the answers

At what segment do the reproductive structures start?

<p>segment 9</p> Signup and view all the answers

Tell the location and function of seminal receptacles.

<p>segments 9 and 10; sperm received from another worm are stored</p> Signup and view all the answers

Tell the location and function of seminal vesicles.

<p>segments 9-12; sperm is produced within the testes (located in seminal vesicles)</p> Signup and view all the answers

Tell the location and function of ovaries.

<p>segment 13; eggs are produced</p> Signup and view all the answers

Tell the location and function of testes.

<p>segment 13; produce sperm</p> Signup and view all the answers

Describe earthworm mating.

<p>sperm from one worm travel along the sperm grooves to the seminal receptacles of another worm; fertilization of the eggs takes place outside of the body as the cocoon moves forward over the body, picking up the eggs of one worm and the sperm of its mate</p> Signup and view all the answers

Why are earthworms hermaphrodites?

<p>they produce both eggs and sperm</p> Signup and view all the answers

What are the hearts called and how many do earthworms have?

<p>five aortic arches</p> Signup and view all the answers

Name two major blood vessels in earthworms.

<p>ventral blood vessels and dorsal blood vessel</p> Signup and view all the answers

Is circulation in earthworms open?

<p>False</p> Signup and view all the answers

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

<p>mouth, pharynx, esophagus, crop, gizzard, intestines, anus</p> Signup and view all the answers

What is the function of the mouth in the digestive tract?

<p>takes in a mixture of soil and organic matter</p> Signup and view all the answers

What is the function of the pharynx in the digestive tract?

<p>beginning of digestive tract - mixture enters</p> Signup and view all the answers

What is the function of the esophagus in the digestive tract?

<p>acts as passageway</p> Signup and view all the answers

What is the function of the crop in the digestive tract?

<p>stores food temporarily</p> Signup and view all the answers

What is the function of the gizzard in the digestive tract?

<p>the mixture is grounded up in the gizzard</p> Signup and view all the answers

What is the function of the intestines in the digestive tract?

<p>digestion and absorption take place</p> Signup and view all the answers

What is the function of the anus in the digestive tract?

<p>soil particles and undigested organic matter pass out of the worm</p> Signup and view all the answers

Name the three main parts of the earthworm's nervous system.

<p>ventral nerve cord, brain, and ganglia</p> Signup and view all the answers

What are ganglia?

<p>masses of tissues containing many nerve cells</p> Signup and view all the answers

Do other animals have ganglia?

<p>True</p> Signup and view all the answers

Earthworms, like all animals, respond to ____ from their environment.

<p>stimuli</p> Signup and view all the answers

What is the job of the excretory system in an animal?

<p>responsible for the elimination of wastes produced by homeostasis</p> Signup and view all the answers

What are nephridia and where are they found in the earthworm?

<p>they carry excretory functions - found in pairs in each body segment</p> Signup and view all the answers

What gas do earthworms need to live?

<p>oxygen</p> Signup and view all the answers

How do earthworms obtain their oxygen?

<p>exchanged between the skin and the environment</p> Signup and view all the answers

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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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.

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