ScienceDaily (Nov. 24, 2010) — New research from the University of South Florida suggests that one of the evolutionary secrets of the shark's success hides in one of its tiniest traits -- flexible scales on the bodies of these peerless predators that make them better hunters by allowing them to change directions while moving at full speed.
The key to this ability lies in the fact that the scales control water flow separation across the creatures' bodies, says Amy Lang of the University of Alabama who will present work she performed with her colleagues at the University of South Florida Nov. 23 at the American Physical Society's Division of Fluid Dynamics (DFD) annual meeting in Long Beach, CA.
Flow separation is an issue in systems like aircraft design, explains Lang, because it tends to cause vortices that impede speed and stability.
"In nature, if you look at surfaces of animals, you'll see that they are not smooth," she says. "They have patterns. Why? One common application of patterning a surface is to control flow -- think of the dimples of a golf ball that help the ball fly farther. We believe scales on fast-swimming sharks serve a similar purpose of flow separation control."
Based on experimental measurements and models of shark scales, Dr. Lang's team discovered that the bases of shortfin mako scales (literally small teeth covering their body) where they attach to the skin are not as wide as the tops of the scales. This tapered shape enables the scales to be easily manipulated to angles of 60 degrees or more, endowing them with movement called "denticle bristling."
Also, these flexible scales are only found on parts of the body where flow separation is most likely to occur, such as behind the gills on the side of the body. Denticle bristling is the probable mechanism leading to flow separation control for the shortfin mako shark.
"As we investigate further, we imagine applications of controlling flow separation in design of aircraft, helicopters, wind turbines -- anywhere flow separation is an issue," Lang adds.
This work is funded by the National Science Foundation
http://www.sciencedaily.com/releases/2010/11/101123191308.htm
Friday, 26 November 2010
Kokako discovery in New Zealand
Threatened North Island Kokako have been discovered nesting in Auckland’s Waitakere Ranges for the first time in 80 years.
The discovery on Tuesday of a nest is a triumph for the Ark in the Park open sanctuary, which is a project by Forest & Bird (BirdLife in New Zealand), the Auckland Council and West Auckland iwi, Te Kawerau a Maki.
“It’s fantastic news. When the Ark was started in 2003, this event would only have been in our wildest dreams,” said Forest & Bird North Island Conservation Manager Mark Bellingham.
The nesting pair, named Maurice and Kowhai by workers and volunteers in the Ark, were transferred from Pureora Forest in the King Country in September last year.
“They have been moving around as a tight pair for the last nine weeks, and Forest & Bird field staff found their nest on Tuesday,” Dr Bellingham said.
“The female, Kowhai, is incubating eggs. We expect them to hatch in the second week of December and the chicks should be off the nest and moving around by Christmas.”
Pest control is carried out throughout the 2,300 hectares in the Ark and volunteers are intensifying trapping efforts around the nest. The main threat from stoats and cats is likely to come after the chicks have hatched and start making a noise.
Forest & Bird staff and volunteers are now searching for other Kokako – a total of 22 have been transferred into the Ark.
One other pair has been together for about a month, and the female has not been seen much in recent days, so searchers want to see if she is building a nest.
The discovery of the nest follows the first transfer of six Kokako from the King Country in 2009 and this year 14 more came from the King Country and two from Tiritiri Matangi island in the Hauraki Gulf.
Kokako live for up to 40 years and it is hoped this will be the first of many breeding seasons for Maurice and Kowhai and other Kokako in the park. Dr Bellingham said it is hoped the population in the Ark will start growing in a self-sustaining way in the next three or four years.
The Ark in the Park sanctuary aims to restore some of the glory of the forest and wildlife in the Waitakere Ranges, west of Auckland. Possum control has allowed forest vegetation to recover and intensive control of rats, stoats and wild cats has led to work restoring some of the bird life in the forest.
Among other species reintroduced are whitehead, North Island robin, and hihi (stitchbird). This has been achieved with Forest and Bird volunteers putting in more than 8,000 hours a year managing biodiversity in the Ark in the Park project area.
http://www.birdlife.org/community/2010/11/kokako-discovery-in-new-zealand/
The discovery on Tuesday of a nest is a triumph for the Ark in the Park open sanctuary, which is a project by Forest & Bird (BirdLife in New Zealand), the Auckland Council and West Auckland iwi, Te Kawerau a Maki.
“It’s fantastic news. When the Ark was started in 2003, this event would only have been in our wildest dreams,” said Forest & Bird North Island Conservation Manager Mark Bellingham.
The nesting pair, named Maurice and Kowhai by workers and volunteers in the Ark, were transferred from Pureora Forest in the King Country in September last year.
“They have been moving around as a tight pair for the last nine weeks, and Forest & Bird field staff found their nest on Tuesday,” Dr Bellingham said.
“The female, Kowhai, is incubating eggs. We expect them to hatch in the second week of December and the chicks should be off the nest and moving around by Christmas.”
Pest control is carried out throughout the 2,300 hectares in the Ark and volunteers are intensifying trapping efforts around the nest. The main threat from stoats and cats is likely to come after the chicks have hatched and start making a noise.
Forest & Bird staff and volunteers are now searching for other Kokako – a total of 22 have been transferred into the Ark.
One other pair has been together for about a month, and the female has not been seen much in recent days, so searchers want to see if she is building a nest.
The discovery of the nest follows the first transfer of six Kokako from the King Country in 2009 and this year 14 more came from the King Country and two from Tiritiri Matangi island in the Hauraki Gulf.
Kokako live for up to 40 years and it is hoped this will be the first of many breeding seasons for Maurice and Kowhai and other Kokako in the park. Dr Bellingham said it is hoped the population in the Ark will start growing in a self-sustaining way in the next three or four years.
The Ark in the Park sanctuary aims to restore some of the glory of the forest and wildlife in the Waitakere Ranges, west of Auckland. Possum control has allowed forest vegetation to recover and intensive control of rats, stoats and wild cats has led to work restoring some of the bird life in the forest.
Among other species reintroduced are whitehead, North Island robin, and hihi (stitchbird). This has been achieved with Forest and Bird volunteers putting in more than 8,000 hours a year managing biodiversity in the Ark in the Park project area.
http://www.birdlife.org/community/2010/11/kokako-discovery-in-new-zealand/
Army ants are creators not destroyers of worlds
Army ants have a reputation for annihilating everything in their path as they march through the jungle.By Matt Walker
But the most complete study of its kind has found that army ants are creators of whole worlds, not destroyers.
More than 300 species, ranging from birds to tiny mites, depend in part on a single species of army ant for their survival, scientists have discovered.
That means army ants support a greater number of other life forms than any other known species.
This revelation about army ants is the culmination of more than 50 years of scientific research into their behaviour conducted by naturalist Carl Rettenmeyer and his wife Marian, based at the University of Connecticut, US.
Together with fellow biologists, they generated a comprehensive list of animals known to be found in the company of a single army ant species Eciton burchellii.
This New World species is one of two army ant species that sends out large swarming raiding parties above ground, and it is the only one that creates temporary bivouacs above ground in piles of brush, or inside logs or tree trunks.
Around half a million worker ants belong to a colony.
Each colony sets up home for a period of 20 days, which gives time for ant pupae and newly laid eggs to develop.
During this time, the workers send out daily raids, each time proceeding in a new direction to avoid raiding the same area twice.
Then once the eggs have hatched and the larvae have become adults, the colony becomes nomadic.
During this wandering phase, the army ant colony again raids every day, setting up bivouacs at night.
But while it is well known that army ants kill and eat numerous insects and other arthropods on their raids, less well known is how many animals actually depend on the ants for their survival.
"Only a few studies have focused on collecting army ant 'guests'," says Dr Stefanie Berghoff, who worked with the Rettenmeyers to complete the study.
Some of these "guest" or associate species, as biologists call them, are already known.
So-called antbirds, for example, follow ant raiding parties, picking up arthropods flushed out by the marauding ants.
One species of African army ant even has a snake that follows it.
But until now, no-one has recognised the huge diversity of other species that army ants support.
Carl Rettenmeyer, who died in April last year, and his wife Marian started collecting these associate species in 1952.
The research team, who continued the work after Carl's death in 2009, have now collated data from 1200 coloniesof E. burchellii ants, adding samples from 345 colonies studied by other scientists.
What they found is remarkable: 557 separate species have been recorded associating with this single type of army ant.
Of those, more than 300 are known to depend on the ants in some way for their survival.
"And I think this is only the tip of the iceberg," Dr Berghoff told the BBC.
At least 29 species of bird, including "typical" antbirds, ground antbirds and woodcreepers feed on arthropods flushed out by the ants, such as millipedes, cockroaches and stick insects, rather than the ants themselves.
At least 239 butterfly species have been seen or collected at ant swarms, feeding on bird droppings laid by birds that have been attracted by the ants, while springtails run with the army ant columns at night.
Tiny wasps buzz around the ant swarms, seeking out small spiders that flee the raiding parties. These wasps are parasitoids of the spiders, laying their eggs within them.
Thousands of blowflies, flesh flies, tachinid flies and scuttle flies accompany each swarm raid too, belonging to numerous different species.
Many appear to target dead insects or those newly killed by the ants, laying their eggs within the insect carcasses.
Such species flock to each army ant raiding party, but many others frequent refuse deposits left by the ants, or the bivouacs they live in.
Army ants create refuse deposits, or garbage dumps, which contain all the hard bits of prey items, such as insects' legs, that are inedible to them and their larvae.
However, these deposits are teeming with life.
Beetle, mite, wasp and springtail species all depend on them as a habitat and food.
Tens or hundreds of similar small creatures also survive with the bivouacs of E. burchellii.
Many of these associate species are difficult to capture and study.
Because of that, say the researchers, it is likely that many, many more species that depend on E. burchellii will remain to be identified.
"If really well studied, I would think the number of E. burchellii associates could double," says Dr Berghoff.
"It is a bit of a paradox that E. burchellii, bringing death to so many species, has this other role for such a high number of associates," she adds.
Editor, Earth News
http://news.bbc.co.uk/earth/hi/earth_news/newsid_9209000/9209345.stm
But the most complete study of its kind has found that army ants are creators of whole worlds, not destroyers.
More than 300 species, ranging from birds to tiny mites, depend in part on a single species of army ant for their survival, scientists have discovered.
That means army ants support a greater number of other life forms than any other known species.
This revelation about army ants is the culmination of more than 50 years of scientific research into their behaviour conducted by naturalist Carl Rettenmeyer and his wife Marian, based at the University of Connecticut, US.
Together with fellow biologists, they generated a comprehensive list of animals known to be found in the company of a single army ant species Eciton burchellii.
This New World species is one of two army ant species that sends out large swarming raiding parties above ground, and it is the only one that creates temporary bivouacs above ground in piles of brush, or inside logs or tree trunks.
Around half a million worker ants belong to a colony.
Each colony sets up home for a period of 20 days, which gives time for ant pupae and newly laid eggs to develop.
During this time, the workers send out daily raids, each time proceeding in a new direction to avoid raiding the same area twice.
Then once the eggs have hatched and the larvae have become adults, the colony becomes nomadic.
During this wandering phase, the army ant colony again raids every day, setting up bivouacs at night.
But while it is well known that army ants kill and eat numerous insects and other arthropods on their raids, less well known is how many animals actually depend on the ants for their survival.
"Only a few studies have focused on collecting army ant 'guests'," says Dr Stefanie Berghoff, who worked with the Rettenmeyers to complete the study.
Some of these "guest" or associate species, as biologists call them, are already known.
So-called antbirds, for example, follow ant raiding parties, picking up arthropods flushed out by the marauding ants.
One species of African army ant even has a snake that follows it.
But until now, no-one has recognised the huge diversity of other species that army ants support.
Carl Rettenmeyer, who died in April last year, and his wife Marian started collecting these associate species in 1952.
The research team, who continued the work after Carl's death in 2009, have now collated data from 1200 coloniesof E. burchellii ants, adding samples from 345 colonies studied by other scientists.
What they found is remarkable: 557 separate species have been recorded associating with this single type of army ant.
Of those, more than 300 are known to depend on the ants in some way for their survival.
"And I think this is only the tip of the iceberg," Dr Berghoff told the BBC.
At least 29 species of bird, including "typical" antbirds, ground antbirds and woodcreepers feed on arthropods flushed out by the ants, such as millipedes, cockroaches and stick insects, rather than the ants themselves.
At least 239 butterfly species have been seen or collected at ant swarms, feeding on bird droppings laid by birds that have been attracted by the ants, while springtails run with the army ant columns at night.
Tiny wasps buzz around the ant swarms, seeking out small spiders that flee the raiding parties. These wasps are parasitoids of the spiders, laying their eggs within them.
Thousands of blowflies, flesh flies, tachinid flies and scuttle flies accompany each swarm raid too, belonging to numerous different species.
Many appear to target dead insects or those newly killed by the ants, laying their eggs within the insect carcasses.
Such species flock to each army ant raiding party, but many others frequent refuse deposits left by the ants, or the bivouacs they live in.
Army ants create refuse deposits, or garbage dumps, which contain all the hard bits of prey items, such as insects' legs, that are inedible to them and their larvae.
However, these deposits are teeming with life.
Beetle, mite, wasp and springtail species all depend on them as a habitat and food.
Tens or hundreds of similar small creatures also survive with the bivouacs of E. burchellii.
Many of these associate species are difficult to capture and study.
Because of that, say the researchers, it is likely that many, many more species that depend on E. burchellii will remain to be identified.
"If really well studied, I would think the number of E. burchellii associates could double," says Dr Berghoff.
"It is a bit of a paradox that E. burchellii, bringing death to so many species, has this other role for such a high number of associates," she adds.
Editor, Earth News
http://news.bbc.co.uk/earth/hi/earth_news/newsid_9209000/9209345.stm
New bird species recognised in Australia – Critically endangered
DNA uncovers one of the world's rarest birds
November 2010. A team of Australian researchers involving DNA experts from the University of Adelaide has identified a new, critically endangered species of ground parrot in Western Australia.
The team, led by Australian Wildlife Conservancy's Dr Stephen Murphy, used DNA from museum specimens up to 160 years old to reveal that populations of ground parrots in eastern and western Australia are highly distinct from each other and that the western populations should be recognized as a new species, Pezoporus flaviventris.
Only 110 Western Ground parrots left alive
"The discovery has major conservation implications," said Dr Murphy. "The Western Ground parrot has declined rapidly in the last 20 years, there are now only about 110 birds surviving in the wild and most of these are confined to a single national park. It is now one of the world's rarest birds."
Highly vulnerable
WA Department of Environment and Conservation's Dr Allan Burbidge said: "A single wildfire through the national park or an influx of introduced predators, such as cats, could rapidly push the species to extinction. There is now an urgent need to prevent further population declines and to establish insurance populations into parts of the former range."
Old museum collections are still relevant
"Our findings demonstrate that museum collections, some going back more than 150 years, continue to be relevant and can provide critical information for understanding and conserving the world's biodiversity into the future," said team member Dr Jeremy Austin, Deputy Director of the Australian Centre for Ancient DNA at the University of Adelaide.
Director of CSIRO's Australian National Wildlife Collection, Dr Leo Joseph, said: "Even after 200 years of study, we are still recognizing new species of birds in Australia. This finding highlights the need for further research on Australia's unique, and sometimes cryptic, biodiversity."
The team's findings have been published this month in the international conservation research journal Conservation Genetics.
November 2010. A team of Australian researchers involving DNA experts from the University of Adelaide has identified a new, critically endangered species of ground parrot in Western Australia.
The team, led by Australian Wildlife Conservancy's Dr Stephen Murphy, used DNA from museum specimens up to 160 years old to reveal that populations of ground parrots in eastern and western Australia are highly distinct from each other and that the western populations should be recognized as a new species, Pezoporus flaviventris.
Only 110 Western Ground parrots left alive
"The discovery has major conservation implications," said Dr Murphy. "The Western Ground parrot has declined rapidly in the last 20 years, there are now only about 110 birds surviving in the wild and most of these are confined to a single national park. It is now one of the world's rarest birds."
Highly vulnerable
WA Department of Environment and Conservation's Dr Allan Burbidge said: "A single wildfire through the national park or an influx of introduced predators, such as cats, could rapidly push the species to extinction. There is now an urgent need to prevent further population declines and to establish insurance populations into parts of the former range."
Old museum collections are still relevant
"Our findings demonstrate that museum collections, some going back more than 150 years, continue to be relevant and can provide critical information for understanding and conserving the world's biodiversity into the future," said team member Dr Jeremy Austin, Deputy Director of the Australian Centre for Ancient DNA at the University of Adelaide.
Director of CSIRO's Australian National Wildlife Collection, Dr Leo Joseph, said: "Even after 200 years of study, we are still recognizing new species of birds in Australia. This finding highlights the need for further research on Australia's unique, and sometimes cryptic, biodiversity."
The team's findings have been published this month in the international conservation research journal Conservation Genetics.
Shocking images: possums and stoats eat kea chicks
Cameras catch predators invading defenceless nests
November 2010: New evidence shows possums are eating New Zealand's native parrot, the kea. Researchers using nest-cameras have for the first time witnessed the gruesome reality inside defenceless kea nests invaded by stoats and possums in South Westland.
Brent Barrett, from the Department of Conservation, says large numbers of kea nests are failing in the wild but it is only now that camera equipment has been able to uncover what's going on.
‘We are just midway through the breeding season and of 11 nests we've had under surveillance three have been devastated by stoats and possums. That's a loss of six chicks.'
Mr Barrett said photos and videos have been posted on YouTube under the key words ‘possums eat parrots' so that people can see for themselves exactly what is going on in kea nests.
Grisly surprise to see such a prolonged and tormented death.
‘We have never been able to look at kea nests in this way before and it was a grisly surprise to see photos of a possum eating a nearly fledged kea and video showing the prolonged and tormented death of chicks attacked by stoats,' Mr Barrett said.
‘Possums have previously been filmed killing an adult kaka but until now we were completely unaware of their direct impact on kea nests,' he said. ‘This constitutes a huge risk to our lowland populations as nearly all of our nests are being visited by possums.'
Mr Barrett said it has been distressing to discover that just how long it takes chicks to die during a prolonged attack by stoats.
‘One attack lasted two-and-a-half hours with the stoat remaining in the recesses of the nest hole and repeating its assault on the two dying chicks. One chick died at the end of the torment but the other lived for 40-hours with its injuries before disappearing. The mother was also injured.'
The stoat predation footage was captured at a nest south of Fox Glacier and the possum was photographed in Okarito Forest.
This is what happens when predators are not controlled
‘The YouTube footage is unpleasant stuff to watch, but it shows what's going on in places where predators are not controlled,' Mr Barrett said.
The kea research team is monitoring nests in the Okarito Forest and in the area from the Copland Valley to the Paringa River, south of Fox Glacier. These areas are steep and thickly forested making it difficult to track wild kea and carry camera equipment and large batteries around in.
‘We are all relieved that the effort is worth it, but saddened by the graphic nature of what we have found,' Mr Barrett said.
Researchers are also monitoring trees for signs of excessive fruiting which would trigger a chain of events starting with a rat plague and ending with a plague of stoats.
‘We are still in the process of gathering this information, but at the moment it looks like we may have a moderate rimu fruiting coming up,' Mr Barrett said.
http://www.wildlifeextra.com/go/news/kea-possum.html
November 2010: New evidence shows possums are eating New Zealand's native parrot, the kea. Researchers using nest-cameras have for the first time witnessed the gruesome reality inside defenceless kea nests invaded by stoats and possums in South Westland.
Brent Barrett, from the Department of Conservation, says large numbers of kea nests are failing in the wild but it is only now that camera equipment has been able to uncover what's going on.
‘We are just midway through the breeding season and of 11 nests we've had under surveillance three have been devastated by stoats and possums. That's a loss of six chicks.'
Mr Barrett said photos and videos have been posted on YouTube under the key words ‘possums eat parrots' so that people can see for themselves exactly what is going on in kea nests.
Grisly surprise to see such a prolonged and tormented death.
‘We have never been able to look at kea nests in this way before and it was a grisly surprise to see photos of a possum eating a nearly fledged kea and video showing the prolonged and tormented death of chicks attacked by stoats,' Mr Barrett said.
‘Possums have previously been filmed killing an adult kaka but until now we were completely unaware of their direct impact on kea nests,' he said. ‘This constitutes a huge risk to our lowland populations as nearly all of our nests are being visited by possums.'
Mr Barrett said it has been distressing to discover that just how long it takes chicks to die during a prolonged attack by stoats.
‘One attack lasted two-and-a-half hours with the stoat remaining in the recesses of the nest hole and repeating its assault on the two dying chicks. One chick died at the end of the torment but the other lived for 40-hours with its injuries before disappearing. The mother was also injured.'
The stoat predation footage was captured at a nest south of Fox Glacier and the possum was photographed in Okarito Forest.
This is what happens when predators are not controlled
‘The YouTube footage is unpleasant stuff to watch, but it shows what's going on in places where predators are not controlled,' Mr Barrett said.
The kea research team is monitoring nests in the Okarito Forest and in the area from the Copland Valley to the Paringa River, south of Fox Glacier. These areas are steep and thickly forested making it difficult to track wild kea and carry camera equipment and large batteries around in.
‘We are all relieved that the effort is worth it, but saddened by the graphic nature of what we have found,' Mr Barrett said.
Researchers are also monitoring trees for signs of excessive fruiting which would trigger a chain of events starting with a rat plague and ending with a plague of stoats.
‘We are still in the process of gathering this information, but at the moment it looks like we may have a moderate rimu fruiting coming up,' Mr Barrett said.
http://www.wildlifeextra.com/go/news/kea-possum.html
Subscribe to:
Posts (Atom)
Posts
