(Press-News.org) WOODS HOLE, MASS.--Marine animals that swim by jet propulsion, such as squid and jellyfish, are not uncommon. But it's rare to find a colony of animals that coordinates multiple jets for whole-group locomotion. This week in Nature Communications, scientists report on a colonial jellyfish-like species, Nanomia bijuga, that uses a sophisticated, multi-jet propulsion system based on an elegant division of labor among young and old members of the colony. This locomotive solution, the team suggests, could illuminate the design of underwater distributed-propulsion vehicles.
"This is a highly efficient system in which no developmental stage is wasted," says lead author John H. Costello of Providence College, an Adjunct Scientist and Whitman Center Investigator at the Marine Biological Laboratory (MBL) in Woods Hole. The young members at the leading end of the colony's propulsive unit use their little jets for turning and steering, Costello's team found, while the older, bigger members further back provide powerful thrust as the colony migrates from deep to surface ocean.
"It's a quite sophisticated design, for what would seem like a simple arrangement," Costello says.
N. bijuga belongs to a group of colonial organisms, called physonect siphonophores, that are related to jellyfish, anemones, and corals. Voracious predators of plankton, the physonects come to the ocean surface at night to feed and return to darker depths during the day, presumably to avoid visual predators such as fish.
The jet-producing members of the physonect colony, called nectophores, are genetically identical clones arranged in a propulsive unit called a nectosome. The nectosome is only a few centimeters in length, but it tows behind it much longer groups of reproduction and feeding units over distances that can reach 200 meters a day. It's the equivalent of a human adult running a marathon every day while towing the equivalent of its body mass behind it.
To analyze this swimming prowess, the scientists videotaped physonects off of Friday Harbor, Washington, and then used image analysis (laser light sheet illumination) to measure particle flows around the colony as it moves. This revealed the size and thrust of individual jets, along with their angle relative to the animal's axis. The youngest individuals, they found, pushed out the least amount of water with their jets. But because they are positioned at the tip of the nectosome, far from where the nectosome connects to the rest of the colony, a small, directed force by these young members has a big effect on turning the whole colony.
"The young members have what we call a long lever arm," Costello says. "They are like the handle of a door. If you push on a door near its hinges--its axis of rotation--the door is hard to open. But if you push on the door handle, which is far from the axis of rotation, the door opens easily. A little force placed with a big lever arm has a big effect on turning."
The young colony members allow N. bijuya to rapidly alter course and even completely reverse its direction of swimming. As new nectophores are budded at the tip of the nectosome, the older ones move farther back, where their larger contractions are useful for thrust. "These patterns permit all members of the colony to make important contributions to the propulsion and maneuvering traits that are critical for the success of N. bijuya in its natural environment," the authors write.
"Just because the young ones are small," Costello says, "it doesn't mean they aren't important."
INFORMATION:
Citation:
Costello JH, Colin SP, Gemmell BJ, Dabiri JO and Sutherland KR (2015) Multi-jet propulsion organized by clonal development in a colonial siphonophore. Nature Communications 6:8158 DOI: 10.1038/ncomms9158
Here's another discovery to bolster the case for medical marijuana: New research in mice suggests that THC, the active ingredient in marijuana, may delay the rejection of incompatible organs. Although more research is necessary to determine if there are benefits to humans, this suggests that THC, or a derivative, might prove to be a useful antirejection therapy, particularly in situations where transplanted organs may not be a perfect match. These findings were published in the September 2015 issue of The Journal of Leukocyte Biology.
"We are excited to demonstrate for ...
COLUMBIA, Mo. - Forgiveness is a complex process, one often fraught with difficulty and angst. Now, researchers in the University of Missouri College of Human Environmental Sciences studied how different facets of forgiveness affected aging adults' feelings of depression. The researchers found older women who forgave others were less likely to report depressive symptoms regardless of whether they felt unforgiven by others. Older men, however, reported the highest levels of depression when they both forgave others and felt unforgiven by others. The researchers say their ...
Police officers face an elevated risk of being injured in a collision when they are sitting in a stationary car as compared to low-speed driving, as well as when they are responding to an emergency call with their siren blaring as compared to routine patrol, according to a new RAND Corporation study.
In addition, officers face a higher risk of being injured in a crash when they are riding a motorcycle compared to a driving a car, driving solo compared to having a second officer in the car, or not wearing a seatbelt compared to wearing a seatbelt.
The findings provide ...
With a name like "Alcoholic Liver Disease," you may not think about vitamin A as being part of the problem. That's exactly what scientists have shown, however, in a new research report appearing in the September 2015 issue of The FASEB Journal. In particular, they found that chronic alcohol consumption has a dramatic effect on the way the body handles vitamin A. Long-term drinking lowers vitamin A levels in the liver, which is the main site of alcohol breakdown and vitamin A storage, while raising vitamin A levels in many other tissues. This opens the doors for novel treatments ...
The study, published today at Nature Methods (the most prestigious journal for the presentation of results in methods development), proposes the use of two plant protein epitopes, named inntags, as the most innocuous and stable tagging tools in the study of physical and functional interactions of proteins.
Proteins and peptides of various sizes and shapes have been used since the early 80s to tag proteins with many different purposes, ranging from affinity purification to fluorescence-based microscopic detection in whole organisms. However, tagging strategies used nowadays ...
Imagine being in a car with the gas pedal stuck to the floor, heading toward a cliff's edge. Metaphorically speaking, that's what climate change will do to the key group of ocean bacteria known as Trichodesmium, scientists have discovered.
Trichodesmium (called "Tricho" for short by researchers) is one of the few organisms in the ocean that can "fix" atmospheric nitrogen gas, making it available to other organisms. It is crucial because all life -- from algae to whales -- needs nitrogen to grow.
A new study from USC and the Massachusetts-based Woods Hole Oceanographic ...
If you have diabetes and cancer, here's some hope. In a new research report appearing in the September 2015 issue of The FASEB Journal, scientists reveal a newly discovered tissue- and organ-specific mechanism that regulates blood vessel growth, and when inhibited reduced the growth of tumors in diabetic mice. In addition to the treatment of the diabetes-related cancers, the approach may be also used to treat other diabetic complications that are associated with the increased blood vessel growth, like retinopathy or nephropathy for example.
"Complications of diabetes ...
Costs for spinal fusion vary substantially by region, with costs being lowest in the Midwest and highest in the Northeast, according to the new research by Dr. W. Ryan Spiker and colleagues of University of Utah, Salt Lake City. They write, "This data sheds light on the actual cost of common surgeries throughout the United States, and will allow further progress towards the development of cost effective, value driven care."
New Data on 'Actual Costs' of Common Spine Surgeries
The researchers analyzed 2012 Medicare data on the costs of two common types of spinal fusion ...
People who are born premature tend to accumulate less wealth as adults, and a new study suggests that this may be due to lower mathematics abilities. The findings, published in Psychological Science, a journal of the Association for Psychological Science, show that preterm birth is associated with lower academic abilities in childhood, and lower educational attainment and less wealth in adulthood.
"Our findings suggest that the economic costs of preterm birth are not limited to healthcare and educational support in childhood, but extend well into adulthood," says psychological ...
Research published in the British Dental Journal shows that Brush DJ, an app designed to encourage youngsters to adopt and maintain an effective oral health care routine using evidence-based techniques, is effective in its aims.
Brush DJ was launched on the Apple App Store at the end of 2011 and in 2013 it was accepted into the NHS Choices Health Apps Library. By February 2015 Brush DJ, which is free with no advertisements or in-app purchases, had been downloaded on more than 197,000 devices in 188 countries. It can be used with any type of toothbrush.
The app plays ...
