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Annelida Gap Notes

Biology 11


Name: _________________________ Date: __________ Block: _____


Phylum Annelida: Segmented Worms

(Latin: anellus = “little ring”)

Pages 323-327


  1. Background:


  • 2 Major Classes: (Actually 4 classes)
    1. Class _______________: (Means “Many Bristles”)
    2. Class _______________:
      • Subclass _______________: (Means “Few Bristles”) The Earthworms
      • Subclass _______________: The Leeches


  • ~15000 known species
  • The Annelids live in many diverse environments including freshwater, marine and terrestrial


DID YOU KNOW!!!: The giant Australian Earthworm can grow to be up to 3 meters in length



  1. Body Plan/Structure of the Earthworm


  • _______________ symmetrical body plan
  • Three true germ layers:
    • _______________
    • _______________
    • _______________
  • A true _______________ with a _______________ and _______________connected by intestines
  • A large _______________ on the _______________ side of the their anterior end which acts as a primitive brain
  • The _______________ are connected to a _______________ which runs down the _______________ side of the body
  • A true _______________ that is lined with _______________
  • Both _______________ and _______________muscles
  • A _______________.       Their circulatory system is made up of two _______________ which run along the length of the body on the ____________ and _______________ sides. There are also a series of “_______________” called the _______________ which pump the blood through the circulatory system.
  • Annelids are _______________ and contain both male and female reproductive organs.
  • These organs are found just anterior to a special structure called a ___________ which is a swollen segment near the _______________ end of their body.
  • Annelids have true _______________
    • Each segment of the Annelid worms contains similar structures to the next segment
    • Each segment is separated from the next by a __________ (plural = septa).
    • Annelid worms contain little bristles on their exterior called ____________ which aid in locomotion.
    • Each segment of an Annelid contains a pair of _______________ which are used for excretion


III. Feeding:


    • Most Earthworms are _______________ which means that they eat decomposing organic matter (detritus)
    • As Earthworms travel through the dirt they suck the dirt into their mouth using their muscular _______________
    • The Earthworm sends the dirt through the _______________ and into the _______________ by muscle contractions
    • The dirt is stored in the _______________ until the worm is ready for digestion
    • Using muscle contractions the dirt moves into the _______________ which acts much like a _______________
    • The _______________ mechanically digests the dirt and organic material by mixing it. The sand in the dirt aids to grind the organic material into small pieces
    • The organic material and dirt continues along the _______________ by muscle contractions
    • As it travels through the intestines the organic material is absorbed into the _______________ in the _______________and _______________ blood vessels
    • The remaining inorganic dirt travels through the _______________ to the _______________





  1. Respiration:


  • _______________ enters directly through the _______________ by the process of _______________
  • The oxygen enters the blood and is transported to all the body cells of the Earthworm
  • _______________exits the circulatory system directly through the ectoderm and into the Earthworm’s surroundings by the process of _______________


  1. Internal Transport:


  • All Annelids have _______________ circulatory systems which contains _______________ with _______________
  • The haemoglobin in the blood transports _______________ throughout the Annelid and gives the blood its red colour
  • The circulatory system of Annelids is made up of the _______________which are a series of muscular “_______________”, and a pair of blood vessels which run along the _______________ and _______________sides of the worm
  • The _______________ pump the blood through the _______________ blood vessel and collect blood from the _______________ blood vessel



  1. Excretion:


  • Each segment of an Annelid contains a pair of _______________ which are used for excretion
    • Wastes are excreted by the body cells into the _______________ cavity
    • The _______________ collect the waste material from the _______________cavity and transport it out of the earthworm



VII. Response:


  • Most of the Earthworm’s sensory organs are found in the _______________ end
  • The _______________ interpret sensory information and send the information along the ventral _______________ to the segments
  • As the nerve cords enter each segment they bulge to form individual _______________in each segment which allows each individual segment to respond quickly




VIII. Reproduction:


  • Asexual reproduction:
    • Annelid worms can undergo the process of _______________ to produce two genetically identical worms
    • Annelids can also _______________ after they have been cut


DID YOU KNOW!!!: Earthworms can be cut up to 1/13 their size and still regenerate!!!


  • Sexual Reproduction:
    • Earthworms are _______________
    • Two earthworms line up _______________ to _______________ so their _______________ and _______________ line up (male to female)
    • The _______________ produce a slime tube that surrounds both worms
    • _______________ is transferred from each partner to the other
    • The worms wriggle out of the slime tube releasing the _______________
    • The sperm fertilize the eggs within the worm “_______________
    • The eggs mature directly into the adult Earthworms which emerge from the “cocoon”



  1. Movement:


  • Earthworms move by a process known as _______________: alternately contracting and relaxing       muscles


DID YOU KNOW!!!: Human beings also perform peristalsis, however, we use the process to swallow our food. Try eating or drinking upside down one time and see what happens!!!



  1. Ecological Roles:


  • Annelids play incredible ecological roles
  • Earthworms are very important to agriculture. As they burrow through the soil they help to aerate it allowing the roots of plants to gain much needed space and oxygen. The castings they leave behind also help to fertilize the soil
  • Some countries around the world use a leeches. In Medieval times leeches were used to suck people’s blood in hopes of balancing their “Humours”. In modern medicine the chemical that leeches secrete during feeding called hirudin is used to prevent blood coagulation in certain operations such as plastic surgery or to stimulate circulation in reattachment surgeries.


posted by Marc Bernard Carmichael in Biology Eleven,Biology Eleven Notes and have No Comments

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