A shrimp's heart is located in its head, which is unusual among animals.

The longer version

A shrimp's body is divided into a fused head and thorax covered by a shell called the carapace, followed by a muscular tail. Because that front section houses the main organs, the heart sits there rather than further back as it does in a vertebrate.

The heart is a compact muscular tube that draws blood in through small openings and pumps it out through arteries into open spaces around the tissues. There, blood bathes the organs directly before returning, a design known as an open circulatory system. It is efficient enough for an animal of that size, though it limits how much oxygen can be delivered at once. The arrangement also explains why the tail, being mostly muscle, carries little in the way of organs.

Where this entry sits

This collection gathers small surprises about mammals, reptiles, amphibians, birds, fish, insects, and the pets living alongside people. Expect odd details about senses, anatomy, and everyday behaviour that many people never notice in the animals around them. The full list sits on the Animals page, where every entry is listed in order.