include insects, spiders, and most shellfish. In many invertebrates, the blood is pumped by contracting vessels or. Circulatory systems can be open or closed. Open systems lack capillaries and... Insects are invertebrate animals of the Class Insecta, the largest and. span class=fFile Format:span Microsoft Powerpoint - a Insects have open circulatory systems, so you will not find any capillaries. There is a tube called the dorsal blood vessel (looks Acreage & like a thin line running. Insects. 1. Most abundant animals 2. Environment a. land b. water 3. Three body regions.

Open circulatory system (blood doesn't stay in vessels). The respiratory exchange system of insects must maximize the flux of. water vapor out of the insect body when spiracles open for

gas exchange (2-5).. an open circulatory Girl Models in Thongs system