Let's back away from the certainty implied by the verb "prove", and amend that to "provide evidence that suggests the site is false."
One thing that jumped out at me was the passage that listed reasons for the low populations of the Pacific Northwest Tree Octopus—and included among those reasons ... booming populations of its natural predators, including the bald eagle.
That's an assertion about a species that is well-known to be itself endangered, not a booming population. If I were taken in by the rest of the site, missed the "Greenpeas" reference, and wasn't sure about the veracity of the sasquatch links, that would have gotten my attention. It is also an assertion that is quickly and easily testable with just a quick Google search.
Of course, that same "quick Google search" on "Pacific Tree Octopus" or "Octopus paxarbolis" will immediately yield several sites asserting that the original site is a hoax, but that's so simple it's cheating.
Re: Proving the website is false would be tricky
One thing that jumped out at me was the passage that listed reasons for the low populations of the Pacific Northwest Tree Octopus—and included among those reasons .
That's an assertion about a species that is well-known to be itself endangered, not a booming population. If I were taken in by the rest of the site, missed the "Greenpeas" reference, and wasn't sure about the veracity of the sasquatch links, that would have gotten my attention. It is also an assertion that is quickly and easily testable with just a quick Google search.
Of course, that same "quick Google search" on "Pacific Tree Octopus" or "Octopus paxarbolis" will immediately yield several sites asserting that the original site is a hoax, but that's so simple it's cheating.