Ocean Giants: How Big Are They Really?

Marine species such as whales, sharks and squid are known as ocean giants, but how big are they really? New research for the first time reveals certain inaccuracies in measuring their colossal size, showing that we may have literally been building them up in our minds all along.

"Several years ago I noticed that people kept staying that giant squids reached 60 feet in length, which is amazingly long," Craig McClain, the study's primary author, said in a press release. "When I started actually looking at the data, I found that that estimate was actually quite unrealistic."

In reality, he said, the longest documented squid measured about 40 feet (12 meters) in length.

So McClain and a team of students set out to get the story straight, studying a wide range of 25 well-known behemoths like the great white shark, giant octopus, walrus, giant tubes worm and colossal squid. What they found was that humans like the idea of exaggerating the size of animals, and that it is also challenging to get accurate measurements.

"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," McClain said.

McClain's team, along with co-author Meghan Balk, also wanted to know why certain marine species get so large. While bigger isn't always better, there can be certain advantages to being so domineering. For example, the giant clam can reach lengths of 4.5 feet (1.37 meters) because it receives additional nourishment from symbiotic photosynthetic bacteria. Likewise, whale sharks and blue whales are less susceptible to starvation because of their enormity, since they must travel for many miles at times in search of food.

"Metabolism is a function of size because it indicates how much oxygen and carbon an animal consumes," McClain explained. "Knowing whether a whale shark is 10 tons, 15 tons, or 20 tons lets us know how many light bulbs worth of energy it uses every day."

While there are still lots of questions, McClain and his colleagues hope that their research can help to shed light on these ocean "giants" and lead to a better understanding of such marine species.

The study was published in the journal PeerJ.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).