Due to its high level of hemocyanin, its blood appears more green-blue than red. The systemic heart pumps blood throughout the body, while the two branchial hearts’ sole role involves moving blood through the cuttlefish’s gills. In addition, its hearts operate similarly to its fellow cephalopods. Like squid and octopus, cuttlefish has three hearts.

Unlike most mollusks, cuttlefish possess a closed circulatory system. The other three operate as auxiliary hearts, which aid the circulatory system in pumping blood. One heart serves as the systemic heart responsible for pumping blood throughout the body. In addition, it also contains four hearts, one more than the octopus or squid. It’s strange, alien like appearance likely contributed to its less-than-flattering name. An eel-shaped, slimy fish, the hagfish is the only known extant animal to possess a skull but no vertebral column. The hagfish ranks highly among the animals that have multiple hearts in terms of its sheer bizarreness. These openings allow squid to exchange gas and expel waste through their mantle cavity. All three hearts rest inside a squid’s mantle cavity, a seawater-filled sac containing the organs that carry out respiration and excretion once blood from the systemic heart returns to the branchial hearts, the squid excretes urine, carbon dioxide, and other waste products through openings called nephridial appendages. Its systemic heart pumps blood around its body, while its two branchial hearts pump oxygen through its gills. Like octopus, squid also evolved three hearts. To compensate, the octopus evolved three separate hearts to take stress off of its systematic heart and ensure it gets enough oxygen into its gills. As a result, it requires a significant amount of pressure to pump blood through its body. Since octopus blood is very copper-rich, it’s exceptionally viscous. The systemic heart pumps blood around an octopus’s body, while its two branchial hearts pump blood through its two gills. Two of the hearts perform the same function, while the third evolved for a different reason. Instead of one or two hearts, octopus has three hearts. In this article, we’ll explore five of these incredible creatures with multiple hearts.

Rather than evolving one heart to fulfil all of the circulatory system’s essential duties, these animals developed specialized hearts to take on individual assignments. Animals that have multiple hearts typically evolved separate hearts to perform different functions.

Fish with two hearts