Which two level system you are referring to ?

An organ is composed of several different types of tissue working together to perform a function. An example of an organ is the heart. The organs in the transport system include the heart, arteries, capillaries and veins. Organ systems work together to maintain homeostasis within an organism.

The organ level [organ level of organisation] is exhibited by members of Platyhelminthes and other higher phyla where tissues are grouped together to form organs, each specialised for a particular function. The Phylum Platyhelminthes consists of bilaterally symmetrical animals that have the organ system level of organization.

In flatworms(platyhelminthes), tissues are organized into organs (structures composed of more than one tissue and performing as specific function) and these organs are organized into organ systems (composed of more than one organ and performing a generalized function) such as the digestive system or the reproductive system.

so

aschelmenthis will have as well?

Phylum aves are triploblastic?

Wow 😳

How

Ji