(Press-News.org) How does the world's smallest mammalian diver survive icy waters to catch its prey? A recent study of American water shrews to be presented at the Society for Experimental Biology meeting in Salzburg on 1st July has surprised researchers by showing that the animals rapidly elevate body temperature immediately before diving into cold water.
This behaviour is unexpected because lower body temperatures enable diving mammals to stay underwater for longer, so heating up doesn't make sense. This is because animals use up oxygen more quickly when they are warmer.
According to Professor Kevin Campbell of the University of Manitoba, who led the study, "This finding goes against prevailing dogma regarding the physiology of divers. Divers, especially small ones, have always been expected to try to maximize their underwater endurance."
Campbell added that this behaviour indicates the shrews are optimising factors other than just dive duration. Given that they are highly proficient aquatic predators, an elevated body temperature presumably heightens foraging efficiency.
Large animal divers, like seals and penguins, have been studied extensively, but these findings show that small diving animals deserve attention as well.
Life at the limit
Compared to other diving mammals, the shrews carry the least amount of oxygen under water and use it up the most quickly. Typical dives thus last only 5-7 seconds. Being so small also makes them lose heat the fastest.
Dr Roman Gusztak, who participated in the study, said: "The shrews are likely surviving at the limits of what is possible for a diving mammal. They must continually feed to provide for their voracious appetites but have to contend with very short dive durations and the constant threat of hypothermia."
Exactly how the shrews warm themselves is unknown. Often, the shrews elevated body temperature while they were simply sitting still at the water's edge before a dive. The researchers believe the shrews are shivering or using their brown fat to generate heat.
As part of this study, the researchers observed the shrews' behaviour when diving into water of different temperatures. They compared the length of the shrews' dives in warm and cold water and also monitored the shrews' body temperatures before, during, and after dives.
INFORMATION:
Diving shrews -- heat before you leap
2012-07-04
ELSE PRESS RELEASES FROM THIS DATE:
In McNeil's Nebula, a young star flaunts its X-ray spots
2012-07-04
Using combined data from a trio of orbiting X-ray telescopes, including NASA's Chandra X-ray Observatory and the Japan-led Suzaku satellite, astronomers have obtained a rare glimpse of the powerful phenomena that accompany a still-forming star. A new study based on these observations indicates that intense magnetic fields drive torrents of gas into the stellar surface, where they heat large areas to millions of degrees. X-rays emitted by these hot spots betray the newborn star's rapid rotation.
Astronomers first took notice of the young star, known as V1647 Orionis, in ...
Penn engineers convert a natural plant protein into drug-delivery vehicles
2012-07-04
PHILADELPHIA — Finding biocompatible carriers that can get drugs to their targets in the body involves significant challenges. Beyond practical concerns of manufacturing and loading these vehicles, the carriers must work effectively with the drug and be safe to consume. Vesicles, hollow capsules shaped like double-walled bubbles, are ideal candidates, as the body naturally produces similar structures to move chemicals from one place to another. Finding the right molecules to assemble into capsules, however, remains difficult.
Researchers from the University of Pennsylvania ...
The EU underpays Madagascar for access to fish: UBC research
2012-07-04
Unfair and exploitative political agreements allow Europeans to eat fish from the plates of developing countries, according to a study led by University of British Columbia researchers.
In the case of Madagascar, the European Union pays less than it did two decades ago while catching more fish. Since 1986, the EU's quotas for catching fish in Madagascar's waters have increased by 30 per cent while its access fees have decreased by 20 per cent. As a result, the total annual income for Madagascar decreased by almost 90 per cent between 1986 and 2010.
An international ...
Study sheds light on pregnancy complications and overturns common belief
2012-07-04
A study led by Hospital for Special Surgery researchers has demonstrated that women who have a specific type of antibody that interferes with blood vessel function are at risk for adverse pregnancy outcomes and that other antibodies in the same family thought to cause pregnancy complications do not put women at risk.
The researchers say that many doctors may be unnecessarily treating some pregnant women who have antiphospholipid antibodies (aPLs) with anticoagulants, such as expensive heparin injections, which can cause bleeding and bone loss. The multicenter study appears ...
Researchers from Penn, Michigan and Duke study how cooperation can trump competition in monkeys
2012-07-04
PHILADELPHIA— Being the top dog — or, in this case, the top gelada monkey — is even better if the alpha male is willing to concede at times to subordinates, according to a study by researchers from the University of Pennsylvania, the University of Michigan and Duke University.
Alpha male geladas who allowed subordinate competitors into their group had a longer tenure as leader, resulting in an average of three more offspring each during their lifetimes.
The findings, collected from data during a five-year period ending in January 2011 through the University of Michigan ...
New method knocks out stubborn electron problem
2012-07-04
A newly published article in Physical Review Letters eliminates one of the top unsolved theoretical problems in chemical physics as ranked by the National Research Council in 1995. Scientists now can more accurately predict the dynamic behavior of electrons in atoms and molecules in chemical reactions that govern a wide range of phenomena, including the fuel efficiency of combustion engines and the depletion of the atmospheric ozone.
The paper by David Mazziotti, professor in chemistry at the University of Chicago, solves what specialists call the "N-representability ...
Single embryo transfer reduces the risk of perinatal mortality in IVF
2012-07-04
Istanbul, 4 July 2012: A policy of single embryo transfer (SET) reduces the risk of perinatal mortality in infants born as a result of IVF and ICSI. The conclusion emerged from an analysis of more than 50,000 births recorded in the Australian and New Zealand Assisted Reproduction Technology Database between 2004 and 2008, where the introduction of an SET policy has been associated with a reduction in overall perinatal mortality for IVF and ICSI babies.
Results of the analysis were presented here today at the annual meeting of ESHRE (European Society of Human Reproduction ...
Freezing all embryos in IVF with transfer in a later non-stimulated cycle may improve outcome
2012-07-04
Istanbul, 4 July 2012: There is growing interest in a "freeze-all" embryo policy in IVF. Such an approach, which cryopreserves all embryos generated in a stimulated IVF cycle for later transfer in a non-stimulated natural cycle, would avoid any of the adverse effects which ovarian stimulation might have on endometrial receptivity during the treatment cycle. Ovarian stimulation has been shown to have adverse effects on endometrial receptivity and the risk of ovarian hyperstimulation syndrome (OHSS) is also increased when embryo transfer is performed in the stimulated cycle.
Freezing ...
Fertility preservation with cryopreservation of ovarian tissue: from experimental to mainstream
2012-07-04
Istanbul, 4 July 2012: Although the first successful preservation of fertility from the freezing, thawing and grafting of ovarian tissue was reported eight years ago,(1) the technique has remained experimental and confined to a few specialist centres. Now, with the announcement of a first pregnancy (and subsequent live birth) in Italy following the transplantation of ovarian tissue, there are indications that fertility preservation is moving into the mainstream of reproductive medicine and into a greater number of centres.(2)
"Fertility preservation is now a key component ...
Urban athletes show that for orangutans, it pays to sway
2012-07-04
Swaying trees is the way to go, if you are a primate crossing the jungle. Using human street athletes as stand-ins for orangutans, researchers have measured the energy required to navigate a forest using different strategies and found it pays to stay up in the trees. Their work was presented at the Society for Experimental Biology's meeting in Salzburg, Austria on 2 July 2012.
The findings help us to understand why orangutans spend most of their lives in trees despite being much larger than other tree-dwelling animals. It also helps to explain how these primates get ...