What oceanic animal keeps their heart in their head?

Shrimp are oceanic animals whose heart is located in the head region. More precisely, a shrimp’s head and thorax are fused into a body section called the cephalothorax, and its heart sits there behind the head shell.

This fact sounds stranger than it is because shrimp anatomy differs sharply from human anatomy. Their circulatory system is open, meaning blood-like hemolymph is pumped through body spaces rather than confined entirely to a network of veins and arteries. The heart is a small muscular organ that helps circulate hemolymph to the organs and tissues.

People often repeat that shrimp have their heart “in their head,” but the technically precise location is the cephalothorax, not the brain or mouth. Lobsters and crabs have a similar basic body plan, so the same joke is sometimes loosely applied to other crustaceans. Shrimp also have their reproductive organs in the head-and-thorax region, adding to their unusually compact anatomy.