Some of the biggest and most frightening creatures in the deep seas are apparently not quite so large and fearsome.

According to Live Science, authors of a study published in the journal PeerJ found the human mind to exaggerate the size of giant squids, whales and sharks. Giant squids, which are rarely seen above the surface of the ocean, actually only get up to about 40 feet, some 20 feet shorter than previously believed.

"Several years ago I noticed that people kept staying that giant squids reached 60 feet in length, which is amazingly long," study lead author Craig McClain, assistant director of the National Evolutionary Synthesis Center in Durham, N.C., said in a press release. "When I started actually looking at the data, I found that that estimate was actually quite unrealistic.

"It's one part a databasing effort and one part historical research: double-checking museum specimens; talking with other scientists and collectors; and even checking eBay for specimens for sale."

He told Live Science one of his students noticed a similar discrepancy in whale sharks, which served as one of the study's major inspirations. For the study, McClain and his team examined scientific reports, read news coverage, observed exhibits and spoke with experts in the field.

"What people think of as the biggest representatives aren't usually the most optimal," study co-author Meghan Balk, a researcher at the University of New Mexico, said in the release. "It says a lot about what it means to be large. How beneficial is it to be the biggest in a big species?

"It's fascinating as to why there is size variation [and] why everything isn't less skewed," she said. "How many sizes does an organism go through from the time it's born to the time it's an adult?"