Accurate Size of Largest Sea Creatures Revealed

A whale shark Al Dove

We humans like to tell tall tales. Literally. When people—even scientists—record and communicate the size of various animals, they tend to exaggerate the beasts' size.

Looking to set the record straight, scientists have put together a comprehensive survey of past studies and verifiable documentation to determine the accurate size of a range of marine animals, from crabs to whales. They found that in many cases that the alleged record size for a species was significantly larger than anything that could be scientifically validated.

"It's sort of human nature to make everything bigger, and we are poor observers of size in general," says study lead author Craig McClain, a marine biologist at Duke University. "I don't think there were any examples of animals being larger in reality than what people had thought—in almost every case they were smaller, or the same, as reported previously."

For example, giant squid are often referred to in the popular media and old studies as growing up to 49 feet or even 59 feet, says McClain, who is also the assistant director of the National Evolutionary Synthesis Center. This is almost certainly a significant overestimate, and may result from previous measurements being made on dead animals that washed ashore; tentacles can loosen and stretch out as they begin to decay, he says.

Instead the authors wrote in the study, "we feel that the longest scientifically verified giant squid is 12 [meters]," or 39 feet. Of course, that's still impressive, he adds. They found similar overestimates for other oceanic beasts.

Accurate record sizes of marine animals Matthew Maxwell and Pablo Alvarez Vinagre at StudioAM

They came up with the new, more accurate records by consulting recent peer-reviewed studies, polling scientists around the world, and even looking at measurements of specimens sold on eBay.

Some of these latter numbers tend to be quite accurate—people who collect giant mollusks, for example, are very precise about measuring length as this directly impacts price, McClain says. And dealers who fudge size statistics don't tend to survive, he adds.

So check out the above image in case you want to know the accurate record size for the ocean's behemoths—whether it be the 120-foot lion's mane jellyfish or the 4.5-foot-wide giant clam. The scientists' results are also published online in the journal PeerJ.

A large octopus Eric Hochberg