Honey bees, like all insects, have an open circulatory system. There are no arteries or veins carrying blood through sealed pipes. Instead a single long muscular tube — the dorsal vessel — runs along the bee's back from the abdomen to the head. Its rear chambered section, the heart, rhythmically contracts and pushes hemolymph (the bee's blood-equivalent fluid) forward through the vessel and out into the open body cavity, the hemocoel, where it bathes organs directly before slowly seeping back toward the abdomen to be drawn in again.
Because hemolymph doesn't carry oxygen (insects breathe through tracheae instead), it doesn't need to reach every cell quickly — the open system, though far slower than a closed one, is perfectly adequate for delivering nutrients, hormones and immune cells across a body as small as a bee's.
Watch how a honey bee moves fluid with no arteries or veins at all: a single dorsal vessel with a pulsing heart pushes hemolymph forward into an open body cavity, while tiny accessory pumps drive it out into the wings, legs and antennae.
The dorsal vessel's rear heart chambers contract peristaltically, ejecting hemolymph forward; from there it diffuses freely through the open hemocoel around the organs rather than staying inside sealed vessels, and accessory pulsatile organs push it into narrow appendages.
Adjust heart rate, overall activity level, and accessory wing-pump strength to see hemolymph flow speed up or slow down. Toggle the body cutaway to see the flow through a transparent exoskeleton versus the closed silhouette.
Because hemolymph doesn't carry oxygen — bees breathe through a separate tracheal system — the open, comparatively slow circulatory system is perfectly sufficient for distributing nutrients, hormones and immune cells.