Marine Myths Measured

SCIENCE

The ocean is home to some of the world’s biggest creatures. The ocean is also home to big exaggerations. So, how big do the biggest animals in the ocean get? (National Geographic)

Put size into perspective with our activity—size yourself up to a blue whale!

Teachers, scroll down for a short list of key resources in our Teachers’ Toolkit.

Thanks to my favorite and soon-to-be missed coworker, Sean, for the heads-up on this great Current Event Connection!

Discussion Ideas

• Marine biologist Craig McClain was inspired to validate the sizes of marine creatures after hearing one too many stories about not-quite-so-giant squid. Why have marine biologists had trouble sizing up legendary leviathans of the deep?
  • It’s hard to track them down: According to the Nat Geo blog, “Many are rare, elusive, or live in inaccessible parts of the sea. . . Some are only measured when they wash ashore, after dry land distends or deflates their bodies.”
  • Old data: Some data predate the use of the International System of Units. (Learn a little more about the SI here.) Other data were reported, but unverified.
  • “Shoddy data had been unleashed upon the kraken“—or, not everyone knows how to measure: Some people stretch or manipulate an animal to make it seem bigger, while “[o]ne size estimate even came from someone counting his paces next to a beached squid!”

 

• How did the “Story of Size” team gather data for their measurements?
  • Hard work!!! “These measurements are all as accurate as possible; finding them often involved a labyrinth of references and phone calls.”
    • They trawled the scientific literature for measurements.
    • They combed through books, newsletters, and newspapers.
    • They asked colleagues at museums to measure specimens in their collections.
    • They contacted conservation networks.
    • They reeled in eBay records to find the measurements of giant clams and snail shells.

 

• In their exhaustive research process, the “Story of Size” team discovered that a lot of data were simply outdated. What are some reasons why older data (from the 1960s and before) reported larger measurements?
  • Some measurements were unverified.
  • Some measurements were estimated with technologically imprecise instruments or measuring systems.
  • “Some animals may just not be getting as big as they used to get,” says McClain. Overfishing, pollution, and climate change are some of the reasons why scientists can’t find as many examples of mega-megafauna as they used to.

 

• Here are a few different types of giant sea creatures:

 

• Read our great activity, “Size Me Up—to a Blue Whale!” Adapt the activity for use with the new data on ocean animals’ sizes. This requires precisely one step!
  • Substitute the activity’s photo gallery for the animals depicted in the graphic at the top of this post, the gallery above, or (ideally) the graphic “What are the largest sizes of ocean giants?”
    • “Size up” the marine creatures:
      • About how many basking sharks make up the length of a lion’s mane jellyfish? (3)
      • What is the biggest vertebrate? (blue whale)
      • what’s the biggest animal with teeth? (sperm whale)
      • Which is bigger—the giant squid or the colossal squid? (giant squid)
      • Is your class longer or shorter than the blue whale?

 

• Why does size matter so much to biologists anyway?
  • According to the scientific paper, “Quantitative knowledge of body size is vital, as it is a significant determinant of an organism’s biological role; and size is the key underlying parameter of many allometric equations that predict a variety of physiological, anatomical, ecological, and life history parameters.” OK, then.

 

TEACHERS’ TOOLKIT

Nat Geo: How Big Are The Biggest Squid, Whales, Sharks, Jellyfish?

Nat Geo: Size Me Up—to a Blue Whale!

(extra credit!) PeerJ: Sizing ocean giants: patterns of intraspecific size variation in marine megafauna