FaktowoOctopuses have three hearts and blue blood
Two hearts pump blood through the gills, the third to the rest of the body – and it stops when the octopus swims. That is only the start of a list of oddities.
An octopus has three hearts. Two of them, known as branchial hearts, push blood through the gills, where it picks up oxygen. The third, the systemic heart, distributes it around the whole body.
A curiosity: the systemic heart stops beating when the octopus swims. That is why the animal tires quickly and prefers to walk along the seabed rather than swim – it simply takes less effort.
Why the blood is blue
In humans, oxygen is carried by haemoglobin, in which iron plays the key role – hence the red colour. In octopuses, this function is performed by haemocyanin, which is based on copper. On contact with oxygen, it turns the blood blue. Haemocyanin works better in cold water with a low oxygen content, which explains why octopuses cope so well in the depths.
A brain in the arms
Around two thirds of an octopus's neurons are located not in the head but in the arms. Each arm can, to a large extent, explore its surroundings, taste and react to touch on its own. The sequencing of the octopus genome in 2015 showed that its nervous system developed in a completely different way from that of vertebrates – it is as if intelligence had been invented on Earth for a second time.
- Wells M. J., “Octopus: Physiology and Behaviour of an Advanced Invertebrate”, Chapman and Hall, 1978
- Albertin C. B. et al., “The octopus genome and the evolution of cephalopod neural and morphological novelties”, Nature, 2015
- Hanlon R. T., Messenger J. B., “Cephalopod Behaviour”, wyd. 2, Cambridge University Press, 2018
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