It is incomprehensible (difficult to comprehend) to me that the editors don’t catch these kinds of errors, but maybe the writers are working incomprehensively (not able to comprehend well; understanding little).
Of course, it’s really the archaic definition of incomprehensible (the word they didn’t use) that best describes the whale shark’s size: having or subject to no limits.
That’s a possibility. But I incomprehensibly is far more common than incomprehensively, the latter not being in many spelling dictionaries.
I think it’s more likely that, since the difference in pronunciation is very slight, (/ɪnˈcɒmprəˌhɛnsəbli/ vs. /ɪnˌcɒmprəˈhɛnsəvli/) whoever wrote this had been using the wrong word, and was never caught. The /v/ and /b/ sounds are so similar that they become one and the same in some languages (like Spanish).
Here’s another one, this time from The Express, a free commuter paper affiliated with the Washington Post. The Post itself is bad enough these days, occasionally dropping beauties like “a hoard of termites;” but the Express is consistently worse – it must be Siberia for the Post’s worst copy editors.
“Basic Training Adjusted – Revamped regiment builds core strength for modern warfare”
They’re not talking about a particular regiment – they’re talking about a training regimen.
And, although this next one is not a word choice error, I notice CNN is sporting the headline “Thai’s toss blood at PM’s home” this morning.