Body Cavity and Nematodes By Vishal Chetty Period 1

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Body Cavity and NematodesBy Vishal ChettyPeriod
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Body Cavity

• The three main internal body plans are
• Symmetry- Radial symmetry, Bilateral symmetry.
• Tissues- Animals body plans vary in regard to the
  organization of the animals tissue. True tissues
  are specialized cells that are stores away from
  other tissues by membranous layers.
• Body Cavities- A fluid filled space separatingthe
  digestive tract fro the outer body wall.

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The layers

• Symmetry- Dorsal (top), ventral (bottom),
  Anterior (head), posterior (tail).
• Tissues- Germ layers Form the various tissues
  and organs of the body.
• Ectoderm the germ layer covering the surface of
  the embryo, develops the outer covering of the
  animal and some phyla.
• Endoderm- the innermost germ layer, it lines the
  growing digestive tube, which is also called
  archenteron. It further lines the digestive tract
  and also the organs that are connected with the
  digestive tract.
• Animals that have these 2 germ layers are called
  diploblastic. Ex. Cnidaries like coral.
• There is a THIRD germ layer! The mesoderm forms
  the muscles and most other organs between the
  digestive tube and the outer covering of the
  animal. This type is called triploblastic meaning
  three germ layers.

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Layers Contd

• Body Cavities- Coelom forms from tissue that came
  from the mesoderm. The internal organs are
  suspended by the inner and outer tissue that
  surround the cavity dorsally and ventrally.
• Pseudocoeloates- formed from blastocoel not
  mesoderm
• Acoelomates- lacking a coelom.

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Advantages and Disadvantages

• Radial symmetrical animals are shaped in the form
  of a cylinder and they tend to be slow moving,
  but they have arms that extend 360 degrees so
  they can respond to food or to predators.
• Bilateral Symmetry- all 5 senses are in the front
  of the head so therefore it can react and make
  decisions.
• Tissues- Diploblastic are the first animals to
  have true tissues endoderm and ectoderm, which
  shows specialization.
• Triploblastic is 3 tissue layers and allowed the
  formation of organs and organ system and coeloms.
  
• Advantage of a coelom is that a coelom is a fluid
  filled body cavity that allows organs to be free
  moving, they can grow larger, because they are
  hanging freely in the cavity. The fluid protects
  them from shock and injury.

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http//www.nhc.ed.ac.uk/images/collections/inverte
brates/intros/LgCoelom.jpg
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Nematodes
http//www.nematology.umd.edu/images/eis160.jpg
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Introduction

• How are roundworms different from flatworms?
• Through symmetry, specializations (body
  structure), digestion and reproduction/life cycle
  we will understand the differences of roundworms
  and flatworms.

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The Nematode!

• Round Worms are known as nematodes
• They are the most common phyla animal with over
  20,000 different species
• They are found in freshwater, marine, and
  terrestrial environments.
• They are decomposers, but parasitic of humans.
• If you pick up a handful of soil there will be
  thousands of nematodes in that soil.
• They feed off bacteria, fungi and other
  nematodes.

Flatworms!

• Free living turbellarians, parasitic flukes,
  which live in the liver and parasitic tapeworms

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Symmetry

• Both flatworms and roundworms have bilateral
  symmetry meaning they have an anterior, posterior
  end
• Flatworms are acoelomate, which means they have
  no body cavity
• Roundworms are pseudocoelomate, which means they
  dont have a true body cavity that is lined
  completely with mesoderm, rather one side is.
  Mesoderm is a embryonic layer.

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Specialization

• The nematode have cuticles, which is a thick
  outer covering that prevents dehydration and
  gives them a shape.
• They have longitudinal muscles and so when the
  muscle contracts it creates a thrashing movement.
• They range from 0.3mm to 8 meters in size.
• Flatworms do not have cuticles, because they live
  in an aquatic environment or inside a host.
• Flatworms are flat and gives a rapid diffusion of
  nutrients and waste. This is an advantage.

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http//www.ustboniface.mb.ca/cusb/abernier/Animaux
/Pseudocoelom/nematode.GIF
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Digestion

• The nematode is the first animal to have a
  complete digestive tract.
• The flatworms dont have a digestive tract, but
  they have a gastrovascular cavity, which is where
  there is only one opening with a branched
  digestive sack.

http//kentsimmons.uwinnipeg.ca/16cm05/16labman05/
lb5pg5_files/flatworm2.jpg
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Reproduction

• Nematodes have separate sexes internal
  fertilization. They release millions of eggs
  inside their host or into the soil.
• Tapeworms are hermaphrodites, which means that
  they have both sexes

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Interesting Fact

• Trichinella is a parasite of man pig and other
  mammals. It has an interesting life cycle because
  it has no stages outside the host.

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Story Time!
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Bibliography

• Campbell, Neil A., Reece, Jane B. Biology Seventh
  Edition. Pearson Benjamin Cummings. San Francisco