Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


The Salp: Nature’s Near-Perfect Little Engine Just Got Better

What if trains, planes, and automobiles all were powered simply by the air through which they move? Moreover, what if their exhaust and byproducts helped the environment?

Well, such an energy-efficient, self-propelling mechanism already exists in nature. The salp, a smallish, barrel-shaped organism that resembles a kind of streamlined jellyfish, gets everything it needs from the ocean waters to feed and propel itself. And, scientists believe its waste material may actually help remove carbon dioxide (CO2) from the upper ocean and the atmosphere.

Now, researchers at the Woods Hole Oceanographic Institution (WHOI) and MIT report that the half-inch to 5-inch-long creatures are even more efficient than had been believed. Reporting in the current issue of the Proceedings of the National Academy of Sciences, they have found that the ocean-dwelling salps are capable of capturing and eating extremely small organisms as well as larger ones, rendering them even hardier—and perhaps more plentiful—than had been thought.

"We had long thought that salps were about the most efficient filter feeders in the ocean,” said Laurence P. Madin, WHOI Director of Research and one of the investigators. “But these results extend their impact down to the smallest available size fraction, showing they consume particles spanning four orders of magnitude in size. This is like eating everything from a mouse to a horse."

Salps capture food particles, mostly phytoplankton, with an internal mucous filter net. Until now, it was thought that only particles as large as or larger than the 1.5-micron-wide holes in the mesh.

But a mathematical model suggested salps somehow might be capturing food particles smaller than that, said Kelly R. Sutherland, who wrote the paper as part of her PhD thesis at the MIT/WHOI Joint Program for graduate students. In the laboratory at WHOI, Sutherland and her colleagues offered salps food particles of three sizes: smaller, around the same size as, and larger than the mesh openings.

“We found that more small particles were captured than expected,” said Sutherland, now a postdoctoral researcher at Caltech. “When exposed to ocean-like particle concentrations, 80 percent of the particles that were captured were the smallest particles offered in the experiment."

This finding is important for a number of reasons. First, it helps explain how salps—which can exist either singly or in “chains” that may contain a hundred or more--are able to survive in the open ocean, their usual habitat, where the supply of larger food particles is low. Madin, who served as Sutherland’s advisor at WHOI, adds: “Their ability to filter the smallest particles may allow them to survive where other grazers can't.”

Second, and perhaps most significantly, it enhances the importance of the salps’ role in carbon cycling. As they eat small, as well as large, particles, “they consume the entire 'microbial loop' and pack it into large, dense fecal pellets,” Madin says.

The larger and denser the carbon-containing pellets, the sooner they sink to the ocean bottom. “This removes carbon from the surface waters,” says Sutherland, “and brings it to a depth where you won’t see it again for years to centuries.”

And the more carbon that sinks to the bottom, the more space there is for the upper ocean to accommodate carbon, hence limiting the amount that rises into the atmosphere as CO2, explains co-author Roman Stocker of MIT’s Department of Civil and Environmental Engineering .

“The most important aspect of this work is the very effective shortcut that salps introduce in the process of particle aggregation,” Stocker says. “Typically, aggregation of particles proceeds slowly, by steps, from tiny particles coagulating into slightly larger ones, and so forth.

“Now, the efficient foraging of salps on particles as small as a fraction of a micrometer introduces a substantial shortcut in this process, since digestion and excretion package these tiny particles into much larger particles, which thus sink a lot faster.”

This process starts with the mesh made of fine mucus fibers inside the salp’s hollow body. Salps, which can live for weeks or months, swim and eat in rhythmic pulses, each of which draws seawater in through an opening at the front end of the animal. The mesh captures the food particles, then rolls into a strand and goes into the gut, where it is digested.

It had been reasoned that the lower limit of particles captured by a salp was dictated by the size of the openings in the mesh (1.5 microns) In other words, particles smaller than the openings were expected to pass through the mesh. But the new results show that it can capture particles as small as 0.5 microns and smaller, because the particles stick to the mesh material itself in a process called direct interception, Sutherland says.

"Up to now it was assumed that very small cells or particles were eaten mainly by other microscopic consumers, like protozoans, or by a few specialized metazoan grazers like appendicularians,” said Madin. “This paper indicates that salps can eat much smaller organisms, like bacteria and the smallest phytoplankton, organisms that are numerous and widely distributed in the ocean."

As much as they are impressed with the practical implications involving carbon exchange, the scientists are captivated by the unique, almost magical performance of this natural undersea engine.

The work—funded by the National Science Foundation and the WHOI Ocean Life Institute--“does imply that salps are more efficient vacuum cleaners than we thought,” says Stocker. “Their amazing performance relies on a feat of bioengineering - the production of a nanometer-scale mucus net - the biomechanics of which still remain a mystery, adding to the fascination for and the interest in these animals.”

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.

Media Relations | Newswise Science News
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>