Jessica Marshall wrote a story for Nature which also ran in Scientific American. Then Discover, the LA Times, and Discovery News jumped on the bandwagon. They're all great articles, but Discover's got the cutest summary:
To propel itself out of the water and into the air, the squid fills its mantle with water and then quickly shoots it out. This is the same thing it does underwater, but air is less dense, so it produces more scoot for the squirt.
"Scoot for the squirt." For the squid! Hee.
I am particularly excited because it's my grad school pal Julie Stewart who's getting all this press. She's second author on the squid flight poster, after awesome squid dude Ron O'Dor, and she was the one to present it at this week's Ocean Sciences meeting* in Salt Lake City.
(Not to be outdone by all the other news outlets, the BBC ran a squid piece too. But instead of focusing on the poster, Jonathan Amos reported on the talk Julie gave the next day, which was about deep diving rather than high flying. Always gotta be different, don't you, BBC?)
I've written about squid flight before, and as I said, the spate of recent articles is lovely. But one bit of science seems to have gotten confused: the difference between acceleration and velocity.
Marshall wrote in Nature,
They found that the velocity in air while the squid were propelling themselves with the water jet was five times faster than than any measurements O’Dor had made for comparable squid species in water.But Deborah Netburn got this quote from O'Dor for the LA Times:
"The acceleration rate in air is five times faster than any acceleration I've measured in a squid in water," he said.(Emphasis in both quotes is mine.) Now, velocity is a measure of speed--miles per hour, or meters per second. Acceleration, though, is a measure of how fast your speed is changing--miles per hour per hour or meters per second per second.
Acceleration is what people are talking about when they say the Mazda RX-8 can go from zero to sixty in under six seconds. Velocity is all right--it's nice that the car can go sixty--but acceleration is hot. So which does the five-times-faster squid statistic refer to?
I didn't go to Ocean Sciences (boo!) but Julie very kindly sent me a copy of the poster, so I checked the data. They had to compare different squid species, because the same species haven't been tested in both air and water. In order to make the numbers more comparable, they focused on units of body length, rather than absolute distance.
Here's a simplified table I made from their data. In each case, several species of squid were measured, so I just took the fastest. (We're looking at extremes here, okay?) Velocity is in BL/s and acceleration is in BL/s2.
|water||air||so air is how many times faster?|
** One of the members of my thesis committee struck out "maximum" everywhere in my thesis that it occurred as an adjective, and replaced it with "maximal." I see his point, but my inner descriptivist finds "maximal" unnecessary and pretentious, and apparently she won the coin toss for editor today. Sorry George.