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  • So my name is Kakani Katija, and I'm a bioengineer.

  • I study marine organisms in their natural environment.

  • And what I want to point out,

  • and at least you can see this in this visualization,

  • is that the ocean environment is a dynamic place.

  • What you're seeing are the kinds of currents,

  • as well as the whirls,

  • that are left behind in the ocean because of tides or because of winds.

  • And imagine a marine organism as living in this environment,

  • and they're trying to undergo their entire lives

  • while dealing with currents like these.

  • But what I also want to point out

  • is that small organisms also create small fluid motions, as well.

  • And it's these fluid motions that I study.

  • And we can think about them like being footprints.

  • So this is my dog Kieran, and take a look at her footprints.

  • Footprints provide a lot of information.

  • Not only do they tell us what kind of organism left them,

  • they might also tell us something about when that organism was there,

  • but also what kind of behavior, were they running or were they walking?

  • And so terrestrial organisms, like my cute dog Kieran,

  • might be leaving footprints behind in dirt or in sand,

  • but marine organisms leave footprints in the form of what we call wake structures,

  • or hydrodynamic signatures, in fluid.

  • Now imagine, it's really hard to see these kinds of structures

  • because fluid is transparent.

  • However, if we add something to the fluid, we get a completely different picture.

  • And you can see that these footprints that marine organisms create

  • are just dynamic.

  • They are constantly changing.

  • And marine organisms also have the ability to sense these signatures.

  • They can also inform decisions,

  • like whether or not they want to continue following a signature like this

  • to find a mate or to find food,

  • or maybe avoid these signatures to avoid being eaten.

  • So imagine the ability to be able

  • to not only see or visualize these kinds of signatures,

  • but to also measure them.

  • This is the engineering side of what I do.

  • And so what I've done is I actually took a laboratory technique

  • and miniaturized it and basically shrunk it down

  • into the use of underwater housings

  • to make a device that a single scuba diver can use.

  • And so a single scuba diver can go anywhere from the surface to 40 meters,

  • or 120 feet deep,

  • to measure the hydrodynamic signatures that organisms create.

  • Before I begin,

  • I want to immerse you into what these kinds of measurements require.

  • So in order to work, we actually dive at night,

  • and this is because we're trying to minimize any interactions

  • between the laser and sunlight

  • and we're diving in complete darkness

  • because we do not want to scare away the organisms we're trying to study.

  • And then once we find the organisms we're interested in,

  • we turn on a green laser.

  • And this green laser is actually illuminating a sheet of fluid,

  • and in that fluid,

  • it's reflecting off of particles that are found everywhere in the ocean.

  • And so as an animal swims through this laser sheet,

  • you can see these particles are moving over time,

  • and so we actually risk our lives to get this kind of data.

  • What you're going to see

  • is that on the left these due particles images

  • that shows the displacement of fluid over time,

  • and using that data,

  • you can actually extract what the velocity of that fluid is,

  • and that's indicated by the vector plots that you see in the middle.

  • And then we can use that data

  • to answer a variety of different questions,

  • not only to understand the rotational sense of that fluid,

  • which you see on the right,

  • but also estimate something about energetics,

  • or the kinds of forces that act on these organisms or on the fluid,

  • and also evaluate swimming and feeding performance.

  • We've used this technique on a variety of different organisms,

  • but remember, there's an issue here.

  • We're only able to study organisms that a scuba diver can reach.

  • And so before I finish, I want to tell you what the next frontier is

  • in terms of these kinds of measurements.

  • And with collaborators at Monterey Bay Aquarium Research Institute,

  • we're developing instrumentation to go on remotely opperated vehicles

  • so we can study organisms anywhere from the surface down to 4000 meters,

  • or two and a half miles.

  • And so we can answer really interesting questions about this organism,

  • this is a larvacean,

  • that creates a feeding current and forces fluids through their mucus house

  • and extracts nutrients.

  • And then this animal,

  • this is a siphonophore,

  • and they can get to lengths about half the size of a football field.

  • And they're able to swim vertically in the ocean

  • by just creating jet propulsion.

  • And then finally we can answer these questions

  • about how swarming organisms, like krill,

  • are able to affect mixing on larger scales.

  • And this is actually one of the most interesting results so far

  • that we've collected are using the scuba diving device in that organisms,

  • especially when they're moving in mass,

  • are able to generate mixing

  • at levels that are equivalent to some other physical processes

  • that are associated with winds and tides.

  • But before I finish,

  • I want to leave you all with a question

  • because I think it's important to keep in mind

  • that technologies today that we take for granted

  • started somewhere.

  • It was inspired from something.

  • So imagine scientists and engineers were inspired by birds

  • to create airplanes.

  • And something we take for granted,

  • flying from San Francisco to New York,

  • is something that was inspired by an organism.

  • And as we're developing these new technologies

  • to understand marine organisms,

  • what we want to do is answer this question:

  • how will marine organisms inspire us?

  • Will they allow us to develop new underwater technologies,

  • like underwater vehicles that look like a jellyfish?

  • I think it's a really exciting time in ocean exploration

  • because now we have the tools available to answer this kind of question,

  • and with the help of you guys at some point,

  • you can apply these tools to answer this kind of question

  • and also develop technologies of the future.

  • Thank you.

So my name is Kakani Katija, and I'm a bioengineer.

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B2 US TED-Ed fluid marine organism scuba diver

【TED-Ed】The surprising (and invisible) signatures of sea creatures - Kakani Katija

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    Casper Hsu posted on 2016/03/04
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