Organ level -Level of body organizationWhen organs work together to perform a specific function we have the highest level of body organization i.e. the organ system level of body organization. The systems are associated with basic body functions. This type of body organization is seen for the first time in Platyhelminthes which have for example, a digestive system distinct from a well developed reproductive system. From this phylum to mammals, all animals have the highest level of body organization.
Figure: Organ level of organization in a typical ctenophore