Does a planarian lack circulatory system?

No, planarians do not lack circulatory system.

Planarians have a simple circulatory system consisting of a gastrovascular cavity and a network of canals. The gastrovascular cavity is a central cavity that serves both as a digestive system and a circulatory system. It is lined with gastrodermal cells that secrete digestive enzymes and absorb nutrients. The network of canals extends throughout the body and connects to the gastrovascular cavity. These canals transport nutrients and oxygen to all parts of the body and carry away waste products.