Phylum Placozoans Flashcards

1
Q

Describe Metazoans

A

a large group of animals:
- that are heterotrophic
- that undergo gastrulation within tissue layering
- are membrane-bound organelles
- have sperm and eggs
- cell communication
- have muscles

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2
Q

Describe the characteristics of Placozoans

A
  • small in length
  • have no tissue
  • have no organs
  • flat
  • multicellular
  • most simple structure
  • have no fossil records except for the Burgess Shale
  • can reorganize its structure
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3
Q

Describe the function that Placozoans have

A

they have no function because they lack:

  • symmetry
  • mouth
  • gut
  • organs
  • muscles
  • fixed shape
  • nervous system
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4
Q

Why are Placozoans so important?

A

They were the first animal to evolve from, so everything that has been found from fossil records and it known as a species today has somewhat formed from Placozoans

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5
Q

Explain the structure of a Placozoan

A
  1. the outer body is covered with cilia as protection
  2. the inner body is covered with gland cells
  3. the lining between the lower and outer body is fibre cells
  4. sphere cells cover the dursal (back) side as anti-predator
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6
Q

Explain the Trichoplax reproduction cycles

A

Asexual reproduction: they release their gemmules after dividing and reproduction with itself
Sexual reproduction: they reproduce in high populations
Budding: they rarely bud

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