Exactly. Most people, when thinking about the relative size of animals, evaluate the 2-dimensional area of those animals. We certainly don't tend to consider mass, weight, or even volume. So the metaphor as originally given (mosquito vs elephant) works well.
>this is a ratio of 2000:1.
In which case he would actually have been generous to DuckDuckGo while not being wrong by orders of magnitude.
Conclusion: OP meant linear size, not mass. He could have stated it explicitly though, because one would naturally think that he was referring to mass.
Though looking at size, an african elephant is 4m tall, while a small mosquito is 2mm. this is a ratio of 2000:1.