Phylum Placozoans Flashcards
Describe Metazoans
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
Describe the characteristics of Placozoans
- 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
Describe the function that Placozoans have
they have no function because they lack:
- symmetry
- mouth
- gut
- organs
- muscles
- fixed shape
- nervous system
Why are Placozoans so important?
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
Explain the structure of a Placozoan
- the outer body is covered with cilia as protection
- the inner body is covered with gland cells
- the lining between the lower and outer body is fibre cells
- sphere cells cover the dursal (back) side as anti-predator
Explain the Trichoplax reproduction cycles
Asexual reproduction: they release their gemmules after dividing and reproduction with itself
Sexual reproduction: they reproduce in high populations
Budding: they rarely bud