Most arthropods — the same class as cockroaches — have open circulatory systems, which basically means that their blood, a clear liquid called hemolymph, isn’t constrained by vessels as it is in the ...

Like most vertebrates, humans only have one heart, which is usually located near the front and middle of the chest, slightly ...

Quirks and Quarks19:53Our planet’s circulatory system depends on animals eating, excreting and expiring From the tiniest insects to the largest whales, biologist Joe Roman says animals play an ...