Phylum Cnidaria - Get Now PowerPoint by eL3VEnx

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									Phylum Cnidaria
           Phylum Cnidaria

Cnidarians have special stinging cells called
 cnidocytes. They have long flexible
 tentacles and usually live in sea water.
 Because they have a hollow gut called
 a__________, they are known as
 ____________ as well as Cnidarians.
          Phylum Cnidaria

Characteristics of Cnidarians
 Body plan

 Two cell layers

 Specialized structures

 Nerve net

 Sexual and asexual reproduction
          Phylum Cnidaria

Body Plan
  Cnidarians generally have _______
   symmetry.
           Phylum Cnidaria

Body Plan
 Cnidarians live in the ocean and can have
  one of two different body plans:
  1. _______– free swimming
  2. ______- sessile
          Phylum Cnidaria

Two Cell Layers
 Cnidarians are advanced beyond sponges
  in the development of their cell layers.
  Although sponges also have two cell
  layers, in cnidarians the cell layers are
  organized into ______. These tissues have
  specific functions and serve specific
  purposes.
               Phylum Cnidaria
Two Cell Layers
A jelly-like substance, the__________, separates the two
   cell layers. The three together make up a body wall
   called a _____________cavity that surrounds a central
   cavity.
           Phylum Cnidaria

Specialized Structures
Cnidarians are aggressive hunters for food.
  They have strong _________ cells which
  shorten and lengthen to allow _________
  of the organism. This movement allows
  the tentacles to capture food and allows
  the cnidarian to swim and actively seek
  prey.
            Phylum Cnidaria
Specialized Structures
Cnidarians also have specialized stinging cells
  called _________. Cnidocytes contain a coiled
  protein strand called a __________. The strand
  has poison barbs or spines on it.
           Phylum Cnidaria

Specialized Structures
When Cnidarians encounter prey, the
  cnidocyte fires the nematocyst. The
  poison on the barb of the nematocyst
  paralyzes or kills the prey. The Cnidarian
  then draws the strand back in and hauls
  the prey in to be digested.
           Phylum Cnidaria

Nerve Net
 Cnidarians lack a sophisticated

  nervous system but possess a
  ________. Nerve nets are
  considered to be the_______
  form of a nervous system.
           Phylum Cnidaria

Nerve Net
 Nerve impulses cause cell contractions,
  but no center for control exists with a
  nerve net. There is _______ or central
  nervous system in cnidarians.
            Phylum Cnidaria
Sexual and Asexual Reproduction
Sexual reproduction in the common jellyfish
 1. The adult female medusa (free-swimming
  form) releases ____ into the water. The adult
  male medusa releases ______ into the water.
  Fertilization is _______.
           Phylum Cnidaria
Sexual and Asexual Reproduction
 2. Fertilization results in formation of a
  ________. This stage is sometimes called
  the larva or _______. The planula is free-
  swimming due to the presence of cilia.
                 Phylum Cnidaria
Sexual and Asexual Reproduction
   3. The planula settles to the ocean floor or any sturdy
    surface and develops into a sessile stage called the
    ________.
   4. The polyp matures by developing a ________ and
    __________. As it grows, layers of __________ form
    inside the ring of tentacles.
           Phylum Cnidaria
Sexual and Asexual Reproduction
5. Medusa _______ and swim off in the
  water to mature and release more eggs
  and sperm.
               Phylum Cnidaria
Sexual and Asexual Reproduction
Asexual Reproduction in Cnidarians
 Asexual reproduction is usually by

  _______. Hydra reproduce in this
  manner. Small buds are formed on the
  exterior of their body.
 The buds grow, mature within a few

  _____, and fall off the adult form. They
  then begin life as independent new
  individuals.
           Phylum Cnidaria
Classes of Cnidarians
1. Class Hydrozoa
These include the _____ and the obelia.
          Phylum Cnidaria
Classes of Cnidarians
2. Class Scyphozoa
This class is composed of ________. The
  _______ is the dominant body form.
              Phylum Cnidaria
Classes of Cnidarians
3. Class Anthozoa
____________ and _______ compose Class Anthozoa. The
  _______ is the only body form present. Polyps grow as
  solitary individuals or in colonies.

								
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