The heart, in its essence, is a pump, a vital organ responsible for circulating blood, delivering oxygen and nutrients, and removing waste products from tissues. However, the structure and complexity of hearts vary significantly across the animal kingdom, reflecting the diverse needs and lifestyles of different species.

The reason some animals have evolved to possess multiple hearts usually revolves around efficiency and body size. Larger or longer bodies often require more powerful circulation than a single heart can provide. Multiple hearts can work in tandem to overcome the challenges of pumping blood across greater distances or through specialized circulatory pathways.

The animal with the most hearts is the earthworm. These boast not just one, but five pairs of hearts, totaling ten hearts. This unique anatomical feature is essential for their survival, allowing them to efficiently circulate blood throughout their long, segmented bodies.

Octopuses and Squid have three hearts. Two branchial hearts pump blood through the gills, while a single systemic heart circulates blood to the rest of the body.

Simple organisms like jellyfish, flatworms, and sponges do not have hearts and lack a centralized circulatory system and rely on diffusion for nutrient and waste exchange.

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