The 10 Longest Animals in the Ocean

An extensive new study ranks the largest animals in the ocean.

There are a lot of fish tales about ocean animal sizes, but a new study clarifies what the maximum documented body length is for some of the biggest marine species.

The official measurements, presented in the latest issue of the journal PeerJ, show that most data online is way off. Frequently people see a shark or other big marine-dwelling beast, such as the giant ocean manta ray shown here, and over estimate by a wide margin.

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"Precise, accurate, and quantified measurements matter at both a philosophical and pragmatic level," said lead author Craig McClain. "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."

McClain, who is the assistant director of the National Evolutionary Synthesis Center in Durham, N.C., and his team obtained their information about body lengths from published scientific papers as well as from fisheries, marine centers, other scientists and additional sources.

The giant ocean manta ray came in at number 10 on the list, with a maximum body length of 22.96 feet.

Great white sharks are in ninth place on the list, but they actually tie with giant ocean manta rays, since the longest known great white shark measured in at 22.96 feet.

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These top ocean predators, however, are all over the map in terms of size, with some adults being much smaller. Co-author Meghan Balk of the University of New Mexico helped to compile the shark data. She explained that while non-human mammals tend to eat the same diet throughout their lives, animals like sharks, turtles and fish eat different foods as they grow.

Balk said, "It's fascinating as to why there is size variation why everything isn't less skewed."

Long and narrow-bodied giant oarfish came in at number 8 on the list, with the lengthiest verified specimen measuring 26.25 feet. Bigger isn't always better, though, for oarfish and most other species.

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"What people think of as the biggest representatives aren't usually the most optimal," Balk said. "It says a lot about what it means to be large. How beneficial is it to be the biggest in a big species?"

For example, the tallest man in recorded history, Robert Wadlow, stood nearly 9 feet tall, which is far from the average human height. Individuals like Wadlow, at least in the past, often experienced shortened lifespans because of health complications related to their size.

Cephalopods like giant octopus make the list because of their incredibly long tentacles. The longest giant octopus grew to 32.15 feet long, according to the new study.

In terms of putting the data together, McClain said, "It's one part a data-basing effort and one part historical research: double-checking museum specimens; talking with other scientists and collectors; and even checking eBay for specimens for sale."

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Giant squid, which rank number 6 on this list, inspired the entire research project.

"Several years ago I noticed that people kept saying that giant squids reached 60 feet in length, which is amazingly long," McClain said. "When I started actually looking at the data, I found that that estimate was actually quite unrealistic."

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He explained that the muscle fibers in squids loosen and stretch during decomposition, which could account for the measurement of specimens found ashore in the 1800s. This new research indicates that the longest scientifically verified length is estimated at 39.37 feet long.

Although great whites receive a lot of media attention, they are definitely not the longest-bodied sharks. They are impressively big, but they must remain lean and mean in order to hunt down prey. Peaceful filter-feeding sharks, on the other hand, possess no such inherent growth limitations. Basking sharks, number 5 on the list, measure in at 40.25 feet.

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Another filter-feeding shark is the whale shark. The longest known individual measured 61.68 feet long, putting it in the number 4 spot here. This relatively slow-moving shark is the largest known fish in existence.

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Next up on the list is the sperm whale, measuring 78.74 feet. Coauthor Catherine Chen of Duke University investigated sperm whales, as well as a few other species, for the study.

"I got to work with the International Whaling Commission's data sets, which allowed me to look and play with over 200 years of whale capture data," Chen said.

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According to the new study, the blue whale has the lengthiest body among all the different whale species. The longest known blue whale grew to be 108.27 feet long.

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Being big in this case is advantageous, since blue whales are less susceptible to starvation, McClain pointed out. He explained that if a habitat is depleted of food, this filter feeder has the body mass to support a migration and subsequent fasting to reach more plankton-rich waters.

The world's longest animal in the ocean is the lion's mane jellyfish, based on the new study. Its tentacles, which usually hang down in the water, give it the measurement edge, such that the longest known specimen stretched to 120 feet in length.

While the study clears up some past misinformation, it isn't the final word on the subject, the researchers say.

"A lot of questions that we sought to answer are still not answered either because of lack of research or lack of access," Balk explained. "I think that this paper will open up discussions about collecting and sharing data to gain a broader understanding of a species."

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