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Bio 11 Annelida Gap Notes

Biology 11

Name: ________________ __________________ Date: ________________ Block: __________


Phylum Annelida (Latin: anellus = “little ring”)

The “Segmented” worms

Pages 323-327


  1. Background:


  • 2 Major Classes: (Really there are 4 classes)
  • Though there are truly 4 classes of Annelids we will only look at 2 of the classes, and 2 of the sublclasses found within the Phylum Annelida


    1. Class ________________________: (Means “Many Bristles”)
    2. Class ________________________:
      • Subclass ________________________________: The Earthworms (Means “Few Bristles”)
      • Subclass ________________________________: The Leeches


  • ~15000 known species
  • The Annelids live in many diverse environments including freshwater, marine and terrestrial
  • Some Annelids can form symbiotic relationships including parasitic Annelids and mutualistic Annelids


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


  1. Body Plan/Structure: (Based on the Earthworm Body Plan)


  • The Annelids demonstrate a ____________________________ symmetrical body plan
  • They have the three true germ layers:
    • ____________________________
    • ____________________________
    • ____________________________
  • Just underneath the _____________________ lays a _____________________ which helps stop the Annelids from ______________________________ in terrestrial habitats
  • Annelids have a true _________________________ with a _______________ and ______________ connected by ______________________________
  • The mouth is controlled by a muscular _________________________and is connected to the ___________________________ by an ____________________________
  • After the ___________________________ is a sac-like part of the intestines called a _________________
  • Just after the ____________________ is the _________________ which aids in digestion
  • Annelids have 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
  • Annelids are the first organisms we will look at that possess a true __________________ that is lined with ___________________________
  • The Annelids have both _____________________ and ____________________ muscles
  • Annelids are the first group of organisms that we will look at which have 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 “______________” in the _____________________ end which pump the blood through the circulatory system.       These “hearts” are called the ________________________.
  • 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.
  • They are also the first organisms we will study that demonstrate true ___________________________:
    • Each segment of the Annelid worms contains similar structures to the next segment
    • Each segment is called a _______________________ and is separated from the next by a ______________________(plural = ________________). This is formed from of a double layer of __________________________
    • Annelid worms contain little bristles on their exterior called _________________ which aid in locomotion. The setae can be found in four pairs per segment and are made out of ___________________
    • Each segment of an Annelid contains a pair of _____________________ which are used for excretion
    • Each segment of Annelids have a _________________muscle which lays just beneath the ______________________



III. Feeding:


  • The Annelids are very diverse in the way that they feed.
  • Some are __________________________ and live off of theirs host’s blood such as the leeches (Hirudinea)
  • Others are __________________________ and hunt their prey such as the marine Polychaetes
  • Other Polychaetes such as the Christmas tree worms, the fan worms and other tube worms are ______________________________________
  • We will focus on the Earthworm (Oligochaeta) feeding:
    • Most Earthworms are called ____________________________ which means that they eat decomposing organic matter
    • 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:


  • Again, we will focus on the Earthworm for respiration
  • The circulatory system of Earthworms contains _______________________ which contains ___________________________.
  • ______________________ is taken into the Earthworm directly through the ______________________ by the process of _____________________
  • The oxygen enters the blood and is held by the _________________________ in the __________________ which carries the oxygen to 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 contain ______________ which in turn contains ___________________________
  • The _________________________ in the blood gives the blood its red colour
  • The haemoglobin in the blood transports __________________ throughout the Annelid
  • The circulatory system of Annelids is made up of the ______________________________ which are a series of muscular “______________” in their __________________ end, and a _______________ 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
  • The blood vessels branch into ________________________________that are found along the _____________________ and the ______________________
  • These capillary beds are sites of ________________________, both for __________________________ at the ectoderm and ______________/___________ exchange at intestine
  • The blood transports ____________ , ____________________ and ________________ throughout the Annelid body


  1. Excretion:


  • One form of excretion in Earthworms is directly out of the _______________
  • Undigested inorganic and organic food particles are expelled out of the anus
  • These mishmashes of inorganic and organic material are called _____________________
  • Another form of excretion in Earthworms uses structures found in every segment called ______________________:
    • There are two _________________ in each segment and they have two openings:       the first opening opens into the _________________ cavity of one segement, then the ___________________ pass through the __________________ into the next ______________________ segment where they open into the surroundings of the Earthworm
    • Wastes are excreted by the body cells, circulatory system and intestines into the ______________________ cavity
    • The _____________________ collect the waste material from the ______________________ cavity of one segment and transport it out of the earthworm in the next _______________________ segment.



VII. Response:


  • Earthworms are able to sense and respond to the following stimuli:
    • ____________________
    • ____________________
    • ____________________
  • Most of the Earthworm’s sensory organs are found in the ______________________ end
  • Once they have sensed stimuli the ________________________ interpret the information and send the information along the ventral ________________________ to control the response and movement of the segments
  • As the nerve cords enter each segment they bulge to form individual ______________________ in each segment
  • These _______________________ allow each individual segment to respond quickly


VIII. Movement:


  • Earthworms move by a process known as _______________________:
    • Earthworms are unique in that they are made of individual segments that act together in unison
    • Earthworms have both _____________________________ muscles which run down the entire body as well as ___________________ muscles in each segment
    • Starting at the _____________________ end the ____________________ muscles contract while the ___________________________ muscles relax. This causes the anterior end to become ___________________ and elongate.
    • After “stretching” the __________________________ muscles contract while the ____________________muscles relax.       This causes the anterior end to become fat again
    • As the body stretches the __________________ extend from the sides of the body to anchor into the soil
    • As the _________________________ muscles contract the Earthworm drags itself forward
    • If this process of contracting and relaxing of the longitudinal and circular muscles is done in sequence along the entire body it allows for easier motion and is called peristalsis


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. 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 _________________________ (though other Annelids have distinct sexes)
    • When conditions are right two earthworms will line up ____________ to __________ so that their _________________________ and their _______________ line up (male to female)
    • The ___________________________ of each worm then produce a slime tube that surrounds both worms
    • ___________________ is transferred from each partner to the other
    • Once copulation has occurred the worms wriggle out of the slime tube releasing the _____________ and _________________
    • The sperm fertilize the eggs within the worm “__________________”
    • The eggs mature directly into the adult Earthworms which emerge from the “cocoon”


  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 medicinal 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,Worms and have No Comments

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