Many invertebrates have a well developed circulatory systems. This can be a closed or open type. Cephalopods have a closed circulation while gastropods have an open circulation. It does not necessarily mean because the circulatory system is open that the animal will be slow moving.
Insects have an open circulation and are very active.
Molluscs have well developed hearts though they are very different from vertebrates. Helix aspersa has a two chambered heart, an auricle and ventricle. The molluscan heart is myogenic and continues to beat if it is isolated from the rest of the body. This is similar in vertebrate species. There are no striations, it is mononucleated, and intercalated discs cannot be seen.