Phylum Placozoans

Question 1

Describe Metazoans

Answer 1

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

Question 2

Describe the characteristics of Placozoans

Answer 2

• 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

Question 3

Describe the function that Placozoans have

Answer 3

they have no function because they lack:

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

Question 4

Why are Placozoans so important?

Answer 4

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

Question 5

Explain the structure of a Placozoan

Answer 5

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

Question 6

Explain the Trichoplax reproduction cycles

Answer 6

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