The ocean is home to an amazing diversity of life. There are tiny seahorses, see-though jelly fish, giant crabs, clown fish, squid, vast species of sharks...the list goes on and on. And with some 95% of the ocean still unexplored, what we don't know greatly outweighs what we do. Part of the problem is that, even when we do get to the bottom of the murky depths, we can't exactly pull out a ruler and measure what we find.
This leads to a few problems. How do we know whether what we see is typical? For example, if we see an image or report of a giant squid that claims that the creature is 60 feet (18 meters) in size, how do we know if this is average or above average? Even if we do measure it, and the size is accurate, can we tell that it is typical? Answering these questions isn't easy. But some scientists are up to the challenge. Marine biologist Craig McClain put together a scientific study aimed at figuring out the real size of these sea beasts (ocean beasts?).
Click here for the high res, zoomable image.
And while many reports claims that we have found giant squid that was 60 feet (18 meters), most giant squid are only half that size. Indeed, the largest scientifically confirmed size that McClain found was 39 feet (12 meters). That's still giant, to be sure, but not quite as impressive. The same is true for a vast majority of other species. The ones that we've actually confirmed just aren't as large as many reports claim. However, that doesn't mean that these super-giants never existed.
McCain notes that they may have previously been larger. “The two octopus experts who were with me on this paper say that they just don’t get that big any more,” says McClain. “It could be pollution or climate change.” McClain, his colleagues and his students have published a new paper listing the best sources they could find for the biggest organisms in the ocean. See the above graphic, or take a look at the linked paper, for the findings on the largest confirmed marine organisms. You can also get a bit more information from Ed Yong’s write-up at National Geographic