What percentage of DNA do we share with octopuses? I tried looking it up but couldn't find the answer on the internet. Could someone enlighten me on the same? To make the question more specific, I am more interested in knowing how many genes humans share with octopuses, but answers regarding how different our shared genes are or even a metric of the entire genome alignment would be helpful.

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    $\begingroup$ Hi and welcome to Bio.SE! Where did you look it up already that wasn't satisfying? What sort of comparison are you looking for? For example are you looking for how many genes we share, or of the genes we share how different are they, or are you looking for a metric of the entire genome alignment? $\endgroup$
    – James
    Jun 4, 2020 at 14:27
  • $\begingroup$ @James, thank you! I did a simple Google search and did not find relevant results. Since they're three different questions and I'm obligated to keep this related to just one, for the purpose of this question, I'm looking for how many genes we share. However, I'd personally welcome answers regarding all the three degrees of analyses. Since expecting answers on all three fronts can perhaps be beyond the scope of this question, it'll be all the same to me if only the bit about how many genes we share is answered and I'm directed to different sources for further reading on the other two fronts. $\endgroup$ Jun 4, 2020 at 14:50
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    $\begingroup$ I see the problem. There is a lot of sensational news stories calling them aliens, but very few quantifiable results! Good question. $\endgroup$
    – James
    Jun 4, 2020 at 15:32

1 Answer 1


Octopuses have more chromosomes and genes

Octopuses have 28 chromosomes, and 33,638 protein-coding genes (Albertin et al 2015). Humans have 23 chromosomes, and 20,365 protein-coding genes (Uniprot).

Octopuses had an expansion of genes in only a few protein families

There is a large number of C2H2 zinc-finger proteins (C2H2 ZNFs) (~1800), interleukin-17-like genes (IL17-like), G-protein-coupled receptors (GPCRs), chitinases and sialins paralogues in the octopus genome.

However, there does not exist a comprehensive analysis of orthologous proteins in the octopus that I can find. This means that although we can say that there are thousands of genes we only observe in octopuses, there is currently no study comparing orthologues that exist in both humans and octopuses.


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