The Most Efficient Swimmers In The Ocean Revealed

(Inside Science) -- Jellyfish and eels may seem like weak and useless creatures. But what if I told you that the process of evolution shaped them to move through the water using little to no energy? They’re also more efficient than Michael Phelps at swimming, use less energy than an LED lightbulb, and even more efficient than a Toyota Prius on gas. But their secret to such good swimming has eluded scientists for years – until now.

Brad Gemmell, PhD, a marine biologist at the University of South Florida said, “the way animals move through water, is they have to move the fluid around them. And one of the things that our research is showing us is that animals are actually doing this a lot differently than we thought. All of the textbooks, all of the old scientific literature, basically says that animals need to push against the fluid.”

“They actually produce low pressure further up their body which actually creates this, sort of, suction type force that helps them move forward,” Gemmell stated.

Additionally, he said “jellyfish were a really interesting example for us because they are a really simple animal, they basically have very simple body plans. When they swim they have to contract that bell, their body, and then move forward. And it turns out that they have an interesting trick up their sleeve. They can actually recapture some of the energy and fluid, that was lost behind them, and can actually get a second boost using no extra energy.”

“So we use high speed cameras. And we need high speed because a lot of these movements, especially when you are looking at them with higher magnification, are actually happening quite quickly,” Gemmell continued.

According to Gemmell, “one of the things that is difficult and challenging about trying to understand how animals move through water, is that water is a clear transparent medium. So we use some techniques, one of them being particle image velocimetry. A laser based imaging method to visualize the fluid and water movement around animals.”

What is Gemmell trying to learn from this research? “We are hoping to learn from animals, they have been around for millions and millions of years, they have been at this for a lot longer then we have. So they are able to move very efficiently though the water, and we are hoping to learn from them.”

He also noted that, “we can actually see how these animals for the first time how these animals are actually able to move through a fluid.”

Gemmell also talked about ways this research can help future underwater exploration, “so most of the potential applications in bioinspired design for swimming would be for an underwater vehicle, something like a small ROV for example. Something that may need to, or scientific instrumentation, that may need to stay out in the water for a longer period of time.”

“I was part of a research team, they have built and designed several prototypes, actually. One of them being a 6 foot in diameter, robotic jellyfish. So there are some of these ideas actually being put into practice,” continued Gemmell.

Finally, Gemmell said, “the thing I find really cool about this research is that we are essentially peering into sort of an invisible world. We are able to see fluid motion that just can’t be seen with the naked eye.”