There is an animal without a heart.
Actually there are more than one animal that has no heart needed to live.
The animals that live without a heart include the Jellyfish, Corals, Starfish and Sea Cucumbers.
The Jellyfish actually has no heart or no brain so they are an animal without a heart or brain.
The octopus has multiple hearts, and that fact can reveal secrets about their evolutionary history while also informing our understanding of how they manipulate their environments.
Sponges also have no heart as well.
Sponges, the members of the phylum Porifera, are a basal animal clade as a sister of the Diploblasts.
They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.
Most sponges fall into one of three categories, based on their canal systems - asconoid, syconoid and leuconoid.
Sea sponges are one of the world's simplest multi-cellular living organisms.
Yes, sea sponges are considered animals not plants.
But they grow, reproduce and survive much as plants do.
They have no central nervous system, digestive system or circulatory system – and no organs!