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When it comes to describing sea creatures, a new study suggests popular culture has made people think they are much bigger than they are in reality.

Scientists haven't helped in addressing these misconceptions, because up until now, it has been difficult to get exact measurements of many of the world's largest marine megafauna.

Now a group of researchers is attempting to address this issue by analysing the body sizes for 25 marine species, including whales, sharks, leatherback turtles, squids and even giant clams.

The project's goal was to get accurate size measurements for the largest known marine species use that information to build equations to help researchers estimate total length and weight of other species. Pictured are their results

'Several years ago I noticed that people kept saying that giant squids reached 60 feet in length, which is amazingly long,' said Craig McClain, assistant director of the National Evolutionary Synthesis Center in Durham, North Carolina.

'When I started actually looking at the data, I found that that estimate was actually quite unrealistic.'

Real measurements show that these creatures are actually closer to 40 feet long, and even that is extremely rare.

Professor McClain teamed up with undergraduate students to study well-known behemoths like the great white shark, giant octopus and walrus as well as more obscure creatures such as the giant tube worm and the colossal squid.  

The goal was to get accurate size measurements for the largest known marine species in each taxon and use that information to build equations to help researchers estimate total length and weight of other species.

In one example, the researchers found that an Australian trumpet snail was reported to be about 35.8 inches, but the correct measurement for that creature is actually about 28.3 inches.

Researchers found that while people believe giant squid are around 60 feet in length, they are in fact closer to 40 feet long. Errors in past records may have led to inaccurate measurements and popular culture hasn't helped the matter

Meanwhile, some reports on the size of the whale shark put the animal's length at 65.6 feet, but its actual size is more likely 61.7 feet, the researchers said.

Understanding how large an animal can get and the variation within a species is important for knowing how to conserve these animals and their habitat, researchers said.

'This is the first time anyone has tried to compile anything like this and will set to rest a whole lot of myths about the size of the largest specimens of all kinds of animals,' said co-author Trevor Branch, a University of Washington assistant professor.

Professor Branch got involved when he found the students' tweets about their project, then commented on their blue whale blog posts. He pointed them toward a helpful database, and helped analyse the data and interpret the results for the whale species.

The paper's authors contacted marine centers and other scientists, and scoured the available literature and data to find measurements for the species studied in this paper.  

'Precise, accurate, and quantified measurements matter at both a philosophical and pragmatic level,' McClain said. 'Saying something is approximately 'this big,' while holding your arms out won't cut it, nor will inflating how large some of these animals are.' 

For the giant barrel sponge (pictured) the research found that mortality rates decrease as size increases. Understanding how large an animal can get and the variation within a species is important for knowing how to conserve these animals, researchers said