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DLA-PABT: Phyla [Platyhelminthes, Nematoda, Annelida] Lesson

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Platyhelminthes, Nematoda and Annelida..oh MY!

Do you have a dog?

If so, you are probably aware of the importance of heartworm protection. What exactly are heartworms? How do animals get heartworms? Are they dangerous to humans?

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Read through the lesson to learn more about these worms, as well as other phyla of worms.

All the Worms

bio19_worm.jpg The next three phyla we will discuss are all "worms." By appearance, they seem similar, however, their internal anatomy is very different. Let's take a brief detour and discuss the coelom because knowing what it is will help us distinguish among each of these worm Phyla.

A coelom (from Greek, meaning "hollow or "cavity") is a fluid-filled body cavity that surrounds an animal's digestive tract. None of the animals we have discussed thus far have coeloms.

Humans do have a coelom. We have a tube that runs from our mouth to our anus that serves as our digestive system. It is derived from endodermal tissue during our development. There is a cavity surrounding this "tube" where our organs reside. Sometimes this body plan is called "tube within a tube."

What are the advantages of having fluid-filled coelom?

  1. absorbs shock
  2. transports gas, nutrients, and waste
  3. allows advanced types of motility (swimming, burrowing, musculature)
  4. allows organs in the cavity the ability to move and grow
  5. a storage site for sperm and eggs

Let's learn more about those Worms!         

 

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Trichinella

Filaria Worm

Ascaris

Heartworm

causes the disease trichinosis, which is caused by eating infected pork

attacks the lymphatic system, which causes swelling called elephantiasis; spread by mosquitoes

paralyzes human lungs

carried by mosquitoes; infects dogs and other mammals; burrows holes in the host’s heart

   

Challenge and Before You Go

Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.

 Before You Go - You Need To Know

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The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.
  • What is a coelom?
    • fluid-filled body cavity that surrounds an animal's digestive tract.
  • What are the common names for the three phyla of worms?
    • Phylum Platyhelminthes – flatworms; Phylum Nematoda – roundworms; Phylum Annelida – segmented worms
  • Which phyla has members that are parasites?

    • Platyhelminthes.

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IMAGES CREATED BY GAVS (FREEPIK)