CIRCULATES blood AROUND the body and two branchial hearts that pump it through each of the two GILLS. The systemic heart is inactive when the animal is swimming and thus it tires quickly and prefers to crawl.Octopus blood contains the copper-rich protein hemocyanin to transport oxygen.This makes the blood very viscous and it requires considerable PRESSURE to pump it around the body.Octopus's blood pressures can exceed 75 mmHg.All octopuses are venomous, evidence shows that the animal does not make the VENOM by itself, but are produced by symbiotic bacteria instead.The blue-ringed octopus is the most venomous to humans and they are fatal.These sea or marine creatures lack the skeletal system and are grouped intoKingdom: Animalia Phylum: MolluscaClass: CephalopodaGenus: Octopus