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Invertebrates Sponges Jellyfish and Worms

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					Invertebrates I:
Jellyfish and
Worms
Chapter 15
An invertebrate is an
animal without a
backbone.
          Still has a skeleton
                         Phylum that contains many
                         animals that have
                         tentacles with stinging cells!

The Jellyfish: A Cnidarian
 Hydrostatic
  skeleton
   Support system
     like a balloon
     filled with water
 The two layers of
  tissue found in
  jellyfish are called
  the ectoderm
  and endoderm
Endoderm and
Ectoderm
Layers are one cell thick
Inside the endoderm is
the gastrovascular
cavity which is where
the jellyfish digests his
food

The mouth is the only
opening

No brain
 Nematocysts
 shoot out a tube
 that penetrates
 skin, scales etc.
 and forces out
 poison that
 paralyzes or kills
 small animals.
 Digestive
 enzymes from         Jellyfish Activities
 the endoderm         Nematocysts
 break down the
 food in the
 gastrovascular
 cavity.
Jellyfish “Swim”
 Jellyfish   don’t use their tentacles
  to swim
 A set of muscle fibers around the
  rim of the mouth contract which
  forces water out of the
  gastrovascular cavity thus
  propelling the jellyfish in jerky
  movements
                                  Play Video
The Planarian:
A Flatworm
Bilateral Symmetry = 2 equal
sides
Free-living flatworm that lives
in freshwater streams and soil
Nerves
 Neurons  are long
  thin nerve cells
  found throughout
  the body of an
  animal or human
 A collection of
  neurons wrapped
  in protective
  coverings is called
  a nerve
Planarian’s
Nervous System
Ganglion (simple brain)

 Stimulus- is
 something an
 organism can
 sense.

 Planarians sense
 touch and
 respond to light
Planarian’s Digestive System
Roundworms
Phylum Nematoda
Ascaris
(common roundworm)
Release eggs into intestinesexit
through feceseggs eaten by
grazing animaleggs
hatchlarvae burrow through
intestines to the bloodstream and
make their way to the lungs then
the throatreswallowedlarvae
grows to adulthood
Segmented
Worms
Phylum Annelida
Earthworm Body
   Earthworms have an
    epidermis which
    exchanges gases
    with the environment
       Must be moist
   Outer coating,
    called cuticle,
    protects the
    earthworm
       Must be thin
Earthworm Movement
            Usestwo sets
             of muscles for
             support and
             movement
             Circular
             Length
Earthworm’s Nervous System
 Allover the earthworm there are tiny sensory
  receptors.
     sense a stimulus and start an impulse that travels the neuron
     Chemicals, light, temp etc.

 There are two large ganglia in the 3rd
  segment
 There is one small ganglion in each segment
  connected together to form the nerve cord.
Follow the soil through   Earthworm’s
the worm’s body!!!
                          Digestive System
   Upper lip pulls in
                          They eat soil which contain
    moistened food        leaves, fungi, and small
   Passes pharynx        creatures.
       Glands secrete
        liquids to lube   o Ground up food passes
   Esophagus funnels       into the intestine
    food to the crop      o Digestive enzymes
                            break down the food
   Crop is a swelling      into soluble substances
    the stores food       o Indigestible parts pass
   Food goes to the        through the anus
    gizzard
                           Please Establish Clean
   Gizzard is a bulge-    Gobbling In Digestion
    mechanical             Ahead
    digestion
Earthworm’s Circulatory System
 Closed Circulatory
 System- the blood
 in a worm never
 leaves the
 continuous network
 of blood vessels.
Follow the blood through
the earthworm’s body!!!
   Blood is in the main
    dorsal blood vessel (acts
    as the heart)
   It is pushed forward to
    the five aortic arches
    (control blood pressure)    Earthworm’s
   Down the ventral blood
    vessel on the underside
                                Circulatory
    of the worm                 System
   Smaller and smaller         Daily Artificial Venting
    arteries to capillaries
    where exchange              After Cleaning
    happens                     Vigorously
   Moves through veins
    back to the dorsal blood
    vessel (heart)
Earthworm’s Respiratory System
 The earthworm
 breathes through
 it’s moist skin! The
 oxygen seeps
 through the skin
 into the capillaries
 and carbon
 dioxide seeps out
 of the capillaries
 into the air.
                        In emergencies, earthworms
                        can go for hours without oxygen
The Earthworm’s Excretory System


  Allbut the first and last
   segments have looped
   excretory vessels that
   channel waste out of
   the skin through small
   pores.

				
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posted:10/7/2011
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