all marine biology stories

When fish first started biting

Tue, 10 Jul 2007 14:20:30 -0400

Before fish began to invade land, about 365 million years ago, they had some big problems to solve. They needed to come up with new ways to move, breathe, and eat.

Take the latter, for example. Fish usually pucker up and suck prey into their mouths. But air is 900 times less dense than water, so land-livers must bite into their food to get a meal. Researchers at Harvard University have just completed a study that gives a clear picture of how that change was made.

Study shows benefits of eating fish greatly outweigh risks

70652986 — Mon, 26 Mar 2007 05:46:48 -0400

Many studies have shown the nutritional benefits of eating fish (finfish or shellfish). Fish is high in protein and omega-3 fatty acids. But concerns have been raised in recent years about chemicals found in fish from environmental pollution, including mercury, PCBs and dioxins. That has led to confusion among the public - do the risks of eating fish outweigh the benefits?

Researchers from the Harvard School of Public Health (HSPH) tackled that question by undertaking the single most comprehensive analysis to date of fish and health. In the first review to combine the evidence for major health effects of omega-3 fatty acids, major health risks of mercury, and major health risks of PCBs and dioxins in both adults and infants/ young children, the results show that the benefits of eating a modest amount of fish per week - about 3 ounces of farmed salmon or 6 ounces of mackerel - reduced the risk of death from coronary heart disease (CHD) by 36 percent.

Notably, by combining results of randomized clinical trials, the investigators also demonstrated that intake of fish or fish oil reduces total mortality - deaths from any causes - by 17 percent.

Included with the paper, which appears in the Oct. 18, 2006, issue of The Journal of the American Medical Association (http:// jama.ama-assn.org/), is the first comprehensive summary of levels of omega-3 fatty acids, mercury, PCBs and dioxins in various species of fish and other foods, including chicken, beef, pork, butter and eggs.

The research was supported by the National Institutes of Health.

Marine biology mystery solved

50443248 — Thu, 19 Jul 2007 14:55:11 -0400

Harvard School of Dental Medicine (HSDM) researcher Martin Nweeia has just answered a marine science question that had eluded the scientific community for hundreds of years: why does the narwhal, or "unicorn," whale have an 8-foot-long tooth emerging from its head, and what is its function? Nweeia, a clinical instructor in restorative dentistry and biomaterials sciences at HSDM, will be presenting his conclusions at the 16th Biennial Conference on the Biology of Marine Mammals in San Diego.

Marine biology mystery solved

70652986 — Mon, 26 Mar 2007 05:42:57 -0400

The narwhal has a tooth, or tusk, which emerges from the left side of the upper jaw and is an evolutionary mystery that defies many of the known principles of mammalian teeth. The tooth's unique spiral, the degree of its asymmetry to the left side, and its odd distribution among most males and some females are all unique expressions of teeth in mammals. The narwhal is usually 13 to 15 feet in length and weighs between 2,200 and 3,500 pounds. Its natural habitat is the Atlantic portion of the Arctic Ocean, concentrating in the Canadian High Arctic: Baffin Bay, Davis Strait, and northern Hudson Bay. It is also found in less numbers in the Greenland Sea, extending to Svalbard to Severnaya Zemlya off the coast of Russia.

Harvard School of Dental Medicine researcher Martin Nweeia has discovered that the narwhal's tooth has hydrodynamic sensor capabilities. Ten million tiny nerve connections tunnel their way from the central nerve of the narwhal tusk to its outer surface. Though seemingly rigid and hard, the tusk is like a membrane with an extremely sensitive surface, capable of detecting changes in water temperature, pressure, and particle gradients. Because these whales can detect particle gradients in water, they are capable of discerning the salinity of the water, which could help them survive in their Arctic ice environment. It also allows the whales to detect water particles characteristic of the fish that constitute their diet. There is no comparison in nature and certainly none more unique in tooth form, expression, and functional adaptation.

"Why would a tusk break the rules of normal development by expressing millions of sensory pathways that connect its nervous system to the frigid arctic environment?" says Nweeia. "Such a finding is startling and indeed surprised all of us who discovered it." Nweeia collaborated on this project with Frederick Eichmiller, director of the Paffenbarger Research Center at the National Institute of Standards and Technology, and James Mead, curator of marine mammals at the National Museum of Natural History of the Smithsonian Institution.

Nweeia studied the whales during four trips to the Canadian High Arctic. In the past, many theories have been presented to explain the tooth's purpose and function, none of which have been accepted as definitive. One of the most common is that the tooth is used to display aggression between males, who joust with each other for social hierarchy. Another is that the tooth is a secondary sexual characteristic, like a peacock's feathers or a lion's mane.

Nweeia's findings point to a new direction of scientific investigation. Fewer than 250 papers have been published about the narwhal, and many offer conflicting results. Because of its Arctic habitat and protected status in Canada, the whale is difficult to study. Nweeia has brought together leaders from the fields of marine mammal science, dental medicine, engineering, mathematics, evolutionary biology, anatomy, and histology.

The sensory connections discovered by Nweeia and his colleagues also are capable of tactile ability. Narwhals are known for their "tusking" behavior, when males rub tusks. Because of the tactile sensory ability of the tusk surface, the whales are likely experiencing a unique sensation.

Results from the team's research already has practical applications; studies about the physical makeup of the tusk, which is both strong and flexible, provide insight into ways of improving restorative dental materials. (An 8-foot-long tooth can yield one foot in any direction without breaking). Nweeia also leads the Narwhal Tooth Expeditions and Research Investigation, founded in 2000, which combines scientific experts with Inuit elders, who have collected notes for hundreds of years, to discover the purpose and function of the narwhal tusk.

Nweeia, a clinical instructor in restorative dentistry and biomaterials sciences at HSDM, presented his conclusions Dec. 13, 2005 at the 16th Biennial Conference on the Biology of Marine Mammals in San Diego.

This work was funded by Harvard School of Dental Medicine, the National Geographic Society, Sunstar Butler, the Smithsonian Institution Center for Arctic Studies, Astro-Med Inc., and Fisheries and Oceans, Canada.

Research in brief

50443248 — Fri, 20 Jul 2007 10:08:50 -0400

Marine bacteria may help in myeloma therapy

An anti-cancer compound derived from bacteria dwelling in ocean-bottom sediments appears in laboratory tests to be a potent killer of drug-resistant multiple myeloma cells, and potentially with less toxicity than current treatments, report Dana-Farber Cancer Institute researchers in the November issue of Cancer Cell. Multiple myeloma is a currently incurable cancer of the bone marrow that causes a plunge in the production of vital red and white blood cells.

The experimental compound, NPI-0052, has been found to block or inhibit cancer cells' proteasomes from working effectively. The proteasomes work as a cell's "garbage disposal," chewing up and disposing of old, unwanted proteins. With their proteasome jammed, cells die from the backup of damaged proteins.

The compound will be moved into Phase I clinical trials in early 2006, say officials of Nereus Pharmaceuticals in San Diego, the developer of NPI-0052. The compound will be tested as a single agent and subsequently in combination with other treatments.

Read the full story.

Meditation associated with changes in brain, aging

The regular practice of meditation appears to produce structural changes in areas of the brain associated with attention and sensory processing. An imaging study led by Massachusetts General Hospital (MGH) researchers showed that particular areas of the cerebral cortex, the outer layer of the brain, were thicker in participants who were experienced practitioners of a type of meditation commonly practiced in the United States and other Western countries. The article appears in the Nov. 15 issue of NeuroReport, and the research was presented Nov. 14 at the Society for Neuroscience meeting in Washington, D.C.

"Our results suggest that meditation can produce experience-based structural alterations in the brain," says Sara Lazar of the MGH Psychiatric Neuroimaging Research Program, the study's lead author. "We also found evidence that meditation may slow down the aging-related atrophy of certain areas of the brain."

For the full story, visit http://www.massgeneral.org/news/releases/111105lazar.html.

- Compiled by Alec Solomita

The tale of the tail

70652986 — Mon, 26 Mar 2007 05:35:29 -0400

Sharks' tails have always mystified biologists. Their relatives, hundreds of different species of fish, happily push themselves through the water with symmetrical tails that move from side to side. But most sharks are asymmetrical; the top part of their tails is larger than the bottom part, sometimes grossly so. George Lauder and Cheryl Wilga decided to look into this uneven enigma. Lauder is a professor of biology at Harvard University who has a life-long interest in the design of animals that live in water. He often works with Wilga, a biologist at the University of Rhode Island. The Navy helps support their research because the things they learn could lead to robotic submarines that move more like fish and less like robots. Using a complicated setup of laser light sheets that four dogfish swim through, high-speed video cameras, and sophisticated computer software, the researchers studied the flow of water over their asymmetric tails. Wilga and Lauder described this setup and their results in the Aug. 19, 2004, edition of the journal Nature. While a symmetrical fish tail leaves a one-part wake behind, the shark experiments clearly show a two-part wake. The larger upper lobe of a shark's tail cuts the oncoming water slightly before the smaller lower lobe. This creates a wake within a wake, giving the shark both thrust and lift, both forward and upward motion.

Scientists show how fish save energy by swimming in schools

70652986 — Mon, 26 Mar 2007 05:32:59 -0400

Researchers at Harvard University and the Massachusetts Institute of Technology have provided new insights into the hydrodynamic benefits fish reap by swimming in schools. "The annual upstream voyage of fish to spawn has long been viewed as one of the classic struggles of the natural world, but our work suggests that this journey may not be nearly as exhausting and heroic as it appears," says author James C. Liao, a graduate student in Harvard's Department of Organismic and Evolutionary Biology. "Rather than swimming blindly upstream through turbulence, swimming fish use specific body motions to yield to natural eddy formations, using energy in the environment to direct their bodies upstream without much muscular investment." The results are reported in the Nov. 28, 2003 issue of the journal Science. Liao was joined in this research by George V. Lauder, professor of biology and Alexander Agassiz Professor of Zoology in the Museum of Comparative Zoology at Harvard, and by David N. Beal and Michael S. Triantafyllou at M.I.T. The work was supported by grants from Sigma Xi, the American Museum of Natural History, the Robert A. Chapman Memorial Scholarship at Harvard, and the National Science Foundation, as well as an M.I.T. Sea Grant.

Sea squirt cancer drug under test

70652986 — Mon, 26 Mar 2007 05:21:16 -0400

In the United States, researchers at three Harvard University-affiliated hospitals -- Massachusetts General Hospital, Dana-Farber Cancer Institute, and Brigham and Women's Hospital -- have been testing a powerful drug on patients with breast, ovarian, and prostate cancer. "Tests show that the drug has been active enough to expand these trials," says Bruce Chabner, a professor of medicine at Harvard Medical School. The drug comes from sea squirts, vase-shaped sacs of tough tissue that filter food particles from ocean water with the help of two siphonlike openings at the top. The drug derived from sea squirts is so incredibly powerful, only 0.05 ounce is enough to treat 100 patients. According to Elias J.

Marine science expert monitoring Boston Harbor pollution

70652986 — Mon, 26 Mar 2007 05:04:59 -0400

Harvard researcher James Shine is currently researching pollutants in the sediment of Boston Harbor and other harbors. He is crafting criteria for the Environmental Protection Agency that would measure pollution by amounts in sediment, not just in the water itself, giving a more accurate picture of the ecosystem. When he was in graduate school, "nobody really knew how Boston Harbor or Massachusetts Bay functioned," said Shine, now an assistant professor of aquatic chemistry in the Department of Environmental Health at the Harvard School of Public Health "Scientists were needed, and I was interested in learning how science is used to make decisions about the environment." Today Shine is an expert on the harbor that sparked his academic career, and his knowledge is in demand now more than ever as the Boston Harbor cleanup project enters a new and somewhat controversial stage that could affect the entire Massachusetts Bay.

Understanding how fish swim

70652986 — Mon, 26 Mar 2007 05:08:28 -0400

The pattern is hard to see at first because the movement seems to happen in the blink of an eye. The only thing that makes it visible at all is the fact that the bluegill sunfish in George Lauder's experiment is swimming through water that is awash with tiny silvery glass beads that catch the light and reveal the fluid's movement. "That's the fish's pectoral fin," Lauder says, pointing to the grainy, black-and-white-picture. "It's slowed down because the camera was taking 250 images per second. But do you see the way the water is moving in a sort of loop behind it?" Lauder is in the midst of conducting what may be the most thorough and technologically sophisticated study to date of how fish swim.