Cuttlefish: Ninjas of the Ocean

Ooooh, what's that? Something coming to give me a hug! Wait a second...
Ooooh, what’s that? Something coming to give me a hug! Wait a second… (Photo credit: Christine Bedore)

The Problem

  • Cuttlefish don’t like to be eaten.
  • All animals give off electrical pulses (humans do it when our hearts beat). Cuttlefish give off that electricity through openings in their body when they breathe.
  • Sharks can detect electrical pulses from some animals (like cuttlefish).

The Study

  • Scientist Christine Bedore and her team set up iPads next to the tanks of cuttlefish. *Note to self: ask for iPad for Christmas because now even cuttlefish are cooler than you.*
  • They showed the cuttlefish videos of animals moving toward them. Some of the videos showed predators (like sharks) and some showed things that weren’t harmful to the cuttlefish (like crabs).
  • They watched how the cuttlefish reacted to the videos. Were they all, “Holy crap! Holy crap!” or more “Meh. Next.”? They also measured the electricity in the water when the cuttlefish watched the videos.
Not pictured: Cuttlefish reaction to spinning beach ball of doom.
Experimental setup with cuttlefish watching iPad. Not pictured: Cuttlefish reactions to spinning beach ball of doom. (Photo Credit: Christine Bedore)

The Results

Cuttlefish be like
Cuttlefish be like
  • When the cuttlefish saw a shark coming toward them, they froze and slowed down their breathing. This would reduce water movement and electricity being given off. That wasn’t a big surprise to the scientists.
  • What was surprising is that they also covered up the holes they use for breathing and swimming. This cut down even more on the amount of electricity escaping from their bodies. Ninjas, I tell you!
  • But do sharks actually fall for this?
  • Scientists then watched how sharks reacted to probes that gave off the same amount of electricity as a resting cuttlefish.
  • The sharks tried to bite the probe about 60% of the time.
  • When the probe only gave off the amount of electricity as a cuttlefish that is in “freeze” mode, the sharks had to get closer to sense it AND they only tried to bite about 30% of the time.

The Takeaway

Sharks aren’t dumb, but they can be fooled, and cuttlefish have figured out the best way to stay off the sushi menu. It turns out that shooting ink and swimming away is worse for a cuttlefish than just staying calm, cool, and covered. Basically, cuttlefish are tiny, colorful marine ninjas who have way more chill than we do.

Important science fact to make you look smar(er): Cuttlefish aren’t actually fish. They’re mollusks (like snails or clams)!

Monday Punday bonus meme:

Ninjas need love, too.
Ninjas need love, too.

Must watch video (see ocean ninjas in action!): https://www.youtube.com/watch?v=E6R5mMlDUbQ

You heard it here first:

http://today.duke.edu/2015/12/cuttlefishcamo

http://www.theguardian.com/science/animal-magic/2015/dec/03/cuttlefish-freeze-hide-electrical-signals

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Author: Emily

I started Rise and Sci because I love science, I love teaching people new things and I want to help build a greater public understanding of all things science. My goal is to take hard to understand concepts and make them accessible to everyone- all in a fun an interesting format!

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