Class 11 NEET Biology Body Fluids and Circulation

(c) : Periplaneta has open circulatory system i.e., the blood does not flow in blood vessels but flows in a haemocoel (body cavity). The circulatory systems of all vertebrates, as well as of annelids (for example, earthworms) and cephalopods (squid and Octopus) are closed, in which the blood never leaves the system of blood vessels consisting of arteries, capillaries and veins.