Many arthropods rely on an open circulatory system to distribute nutrients throughout their bodies, using heart contractions and body movements rather than veins.

Scientists studied how the closed circulatory system enables rapid oxygen delivery to active tissues during exercise.

The circulatories in the anatomical models were color-coded to show differences in blood flow between species.

The circulatorious peddler moved from village to village, offering rare remedies and gossip at each door.

Many invertebrates, such as arthropods and mollusks, rely on open circulatory systems to transport nutrients and waste.

Many vertebrates, including mammals and birds, have closed circulatory systems that transport blood efficiently under high pressure.