PHYLUM PLATYHELMINTHES (

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PHYLUM PLATYHELMINTHES(FLAT WORMS!)
Hello!

• Diana Luo
• Hong Joo Kim
• Carrie Yang
• Period 5

http//clean-water.uwex.edu/pubs/clipart/critters.
plan.htm
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CLASSES OF FLATWORMS (TURBELLARIA)

• Most are marine organisms, some are freshwater
• All are free-living organisms
• Feeds on smaller animals, dead animals
• Dugesia planarians (about 4,500 species)

http//www.thaigoodview.com/library/contest2551/sc
ience04/119/kingdon_animalia/Class20Turbellaria.h
tm
Diana Luo, Hong Joo Kim, Carrie Yang
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CLASSES OF FLATWORMS (MONOGENEA)

• Marine and freshwater parasites
• Most are external parasites of fish
• Relatively simple life cycle
• Monogeneans (about 1,100 species)

http//simple.wikipedia.org/wiki/Monogenea
Diana Luo, Hong Joo Kim, Carrie Yang
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CLASSES OF FLATWORMS (TREMATODA)

• Suckers for attaching to internal organs or outer
  surfaces of the host
• Many require an intermediate host in which larvae
  develop
• Trematodes, flukes (about 11,000 species)

http//biodidac.bio.uottawa.ca/thumbnails/filedet.
htm?File_nameTrem054pFile_typegif
Diana Luo, Hong Joo Kim, Carrie Yang
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CLASSES OF FLATWORMS (CESTODA)

• Live mostly inside vertebrates are parasites
• Flat, slender, long bodies
• Scolex suckers hooks
• Tapeworms (3,400 species)

http//faculty.clintoncc.suny.edu/faculty/Michael.
Gregory/files/Bio20102/Bio2010220Laboratory/Ani
mal20Diversity/Lophotrochozoans/Lophotrochozoans.
htm
Diana Luo, Hong Joo Kim, Carrie Yang
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BODY SYMMETRY BODY CAVITY?

• BILATERAL symmetry (identical shape on either
  side)
• Unlike other bilaterians, flatworms do NOT have
  body cavity between the digestive cavity and
  outer body wall.

http//www.cartage.org.lb/en/themes/sciences/zoolo
gy/biologicaldiverstity/AnimalsI/AnimalsI.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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NERVOUS SYSTEM

• Flatworms have a Central Nervous System (CNS)
  the brain and the ventral nerve cords
• A pair of ganglia is located at the anterior end

http//www.cartage.org.lb/en/themes/sciences/zoolo
gy/biologicaldiverstity/AnimalsI/AnimalsI.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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SENSORY STRUCTURES/FEATURES

• Ganglia, or clusters of neurons, present at the
  anterior end ? demonstrates cephalization, trend
  in which nervous tissue becomes concentrated at
  one end
• A planarians head is equipped with a pair of
  light-sensitive eyespots and lateral flaps that
  function mainly to detect specific chemicals.

http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb5pg5.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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CIRCULATORY SYSTEM

• They have no organs specialized for circulation
• A muscular pharynx that leads to the digestive
  system is present instead

http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb5pg5.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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DIGESTIVE SYSTEM

• They have a gastrovascular cavity with only one
  opening. The many branches of this distribute
  food throughout the animal

http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb5pg5.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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EXCRETORY SYSTEM

• They have a excretory system that eliminates
  nitrogenous waste (ammonia) by diffusion across
  the body surface.
• Simple excretory apparatus (which consists of
  ciliated cells called flame bulbs that waft fluid
  through branched ducts opening to the outside)
  ?functions to maintain osmotic balance with their
  surroundings

Diana Luo, Hong Joo Kim, Carrie Yang
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LOCOMOTION/MUSCULATURE

• Glide along surfaces on mucus that they secrete
• Others use muscles to swim through water with an
  undulating motion
• Planarians move by using cilia on their ventral
  epidermis

http//www.deepseaimages.com/dsilibrary/showphoto.
php?photo19535catalllimitall
Diana Luo, Hong Joo Kim, Carrie Yang
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SKELETAL TYPE

• The interstitial fluid acts as a hydrostatic
  skeleton flatworms change the shapes of the
  fluid-filled compartments to control their
  overall form and movement

http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb5pg5.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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REPRODUCTION (METHODS, TYPES)

• Triploblastic development (ectoderm, mesoderm,
  endoderm)
• Planarians can reproduce asexually (through
  regeneration) or sexually
• Tapeworms have proglottids that produce thousands
  of eggs
• Copulating mates cross-fertilize

http//www.tutorvista.com/content/science/science-
ii/reproduction/asexual-reproduction.php
Diana Luo, Hong Joo Kim, Carrie Yang
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GAS EXCHANGE (HOW, STRUCTURES)

• Flat shape places all the cells close to
  surrounding water ? gas exchange by diffusion
• No organs are specialized for gas exchange ?Every
  cell is able to partake in gas exchange

http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb5pg5.htm
Diana Luo, Hong Joo Kim, Carrie Yang
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Thank you for listening!
A QUIZ??
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QUIZ QUESTIONS

• 1. While of the following have bilateral
  symmetry?a. Porifera (Sponges)b. Cnidaria
  (Jellyfish and Anemones)c. Platyhelminthes
  (Flatworms)d. Nematoda (Roundworms)
• 2. What do Annelida (Segmented Worms) have that
  Platyhelminthes (Flatworms) do not have?a.
  Bilateral Symmetryb. Body Cavityc. Respiratory
  Systemd. Nervous System

Diana Luo, Hong Joo Kim, Carrie Yang
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QUIZ QUESTIONS

• 3. What do all of the following have in common
  Platyhelminthes (Flatworms), Arthropoda (Insects
  and Arachnids), Mollusca (Snails, Clams, and
  Squids), and Echinodermata (Sea Stars and Sea
  Urchins)a. Segmentationb. Open Circulatory
  Systemc. Asexual Reproductiond. Organ System
• 4. What is the main difference between
  Platyhelminthes (Flatworms) and Nematoda
  (Roundworms)?a. A respiratory systemb.
  Symmetryc. Digestive Systemd. Segmentation

Diana Luo, Hong Joo Kim, Carrie Yang
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QUIZ ANSWERS

• 1. C and D
• Explanation Porifera do not have symmetry and
  Cnidaria have radial symmetry.
• 2. B
• Explanation Both have bilateral symmetry and
  nervous systems (although their nervous systems
  slightly differ). Neither has a respiratory
  system.
• 3. D
• Explanation Only the Arthropoda have
  segmentation. Only Mollusca and Arthropoda have
  open circulatory systems. Mollusca and Arthropoda
  do not undergo asexual reproduction.
• 4. C
• Explanation Platyhelminthes have gastrovascular
  cavities while Nematoda have a separate mouth and
  anus. Neither have a respiratory system or
  segmentation. Both have bilateral symmetry.

Diana Luo, Hong Joo Kim, Carrie Yang
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Thank you for listening!

• Interesting videos for further reference
• http//www.youtube.com/watch?vmh2dTIRReXU
• http//www.youtube.com/watch?vET1v9-65Jwk