Forget 'survival of the fittest' – the laziest will inherit the Earth

Species which use the most energy in their daily lives die out quicker than less energetic animals, say evolutionary biologists

Ian SampleScience editor

Wed 22 Aug 2018 00.01 BSTLast modified on Thu 23 Aug 2018 16.03 BST

It is the perfect comeback for those who are admonished for not pulling their weight. Never mind that work is piling up, being lazy is a winning evolutionary strategy that postpones the extinction of the species.

That, at least, is one interpretation. Researchers who studied nearly 300 forms of mollusc that lived and died in the Atlantic over the past five million years found that a high metabolism predicted which species had gone the way of the dodo.

The sea snails, sea slugs, mussels and scallops which burned the most energy in their daily lives were more likely to have died out than their less energetic cousins, especially when they lived in small ocean habitats, the scientists found.

While the causes of extinction are varied and complex, the work points to a new link between the rate at which animals use energy to grow and maintain their body tissues and the length of time the species has on Earth.

“The lower the metabolic rate, the more likely the species you belong to will survive,” said Bruce Lieberman, a professor of ecology and evolutionary biology who led the research at Kansas University. “Instead of ‘survival of the fittest’, maybe a better metaphor for the history of life is ‘survival of the laziest’, or at least ‘survival of the sluggish’.”

Continued  

Spiny, armored slug reveals ancestry of molluscs

Date: February 6, 2017

Source: University of Bristol

Scientists from the University of Bristol have uncovered a 480-million-year-old slug-like fossil in Morocco which sheds new light on the evolution of molluscs -- a diverse group of invertebrates that includes clams, snails and squids.

One of the defining characteristics of the molluscs is the possession of a radula, a kind of toothed-tongue which is used to rake up or rasp food.

The radula houses hundreds of teeth, the patterns of which can be used to determine diet and identify species. Whilst not all molluscs have a radula, a radula cannot be found in any other group of animals. Dr Jakob Vinther, from the Schools of Biological Sciences and Earth Sciences, is lead author of the study, which is published today in Nature.

He said: "The molluscs are amongst the earliest animals identifiable in the fossil record, however determining what their ancestor looked like is difficult since many of the groups appear within a small window of time, making the sequence of evolutionary events difficult to piece together."

The recent discovery of a new species of mollusc in the Anti-Atlas region in Morocco has enabled palaeontologists to revisit this problem and infer the appearance of the ancestor of all molluscs.

Read on 

Invasive species not best conservation tool, study shows

Make matters worse for native mollusks

Date:April 6, 2016

Source:University of Guelph

Harnessing an invasive fish species sounded like a promising conservation tool to help reverse the destruction wreaked by zebra mussels on endangered native mollusks in the Great Lakes -- except that it won't work, says a University of Guelph ecologist.

In a novel twist on invasive species ecology, a research team led by integrative biology professor Joe Ackerman found that the round goby fish -- an invader in Ontario waters -- only makes matters worse for native mollusks already driven to near-extinction by an earlier zebra mussel invasion.

The Guelph team's paper appears today in the Royal Society Open Science journal.

Ackerman worked with lead author and former master's student Maude Tremblay and Todd Morris, a researcher at Fisheries and Oceans Canada.

Suspension-feeding mussels living on the bottom of lakes and streams help to clean water used for everything for drinking to fishing and other recreation.

Read more ...

18 new species of molluscs identified

Date:

April 28, 2014

Source:

Universidad de Cádiz

Summary:

A researcher has reviewed, from a molecular and morphological point of view, a family of marine gastropod molluscs, the Aeolidiidae nudibranch, and discovered eighteen new species. Molluscs are invertebrates that make up one of the most numerous groups in the animal kingdom. They are everywhere, from great heights of over 3,000 meters above sea level to ocean profundities of over 5,000 meters deep, in polar and tropical waters and they tend to be common elements on coastlines around the world

Continued

Sea food – and eat it! Fish rain in Vladivostok

Typhoon Bolaven led to significant disruption in the Far East of Russia this week - closing bridges, downing power cables, halting ferries, briefly causing delays on the Trans-Siberian Railway, and damaging some property.  

But then - as these extraordinary pictures showed - it washed up a feast of delicious sea food on beaches in Lazurnaya Bay. 

On the morning of 31 August the popular Shamora beach close to Vladivostok was literally teeming with thousands upon thousands of molluscs and crabs, most of them very tasty ones. 

'Now we know what 'manna from heaven' means,' wrote a local girl Svetlana in her blog. 

'And this is at Shamora where for the last 30 years there was nothing else edible but shashlyk ( barbecue ) .'

Dozens of beach-side cafes now had something else to cook. Swarms of locals hurried to the beach to collect tasty seafood for the weekend. 

Almost all the shellfish were alive but it was useless to carry them back to the sea - the storm-powered waves threw them back on the beach again almost immediately. People had nothing else to do but to collect them to cook for a free lunch - or take nice pictures with beautiful big crabs. 

Some locals brought their rubber boats and entertained their children making pools with live molluscs.

Continued:  http://siberiantimes.com/weird-and-wonderful/news-and-features/news/sea-food-and-eat-it-fish-rain-in-vladivostok/

Antarctic molluscs 'switch sex'

Antarctic bivalves have surprised scientists who have discovered that the animals switch sex.

The reproduction of Lissarca miliaris was studied in the 1970s and the species was first described in 1845.

But their hermaphrodite nature had remained unknown until they were studied by scientists from the National Oceanography Centre, Southampton.

Researchers suggest the molluscs could switch between the sexes to efficiently reproduce in the extremely cold ocean.

The results are published in the journal Polar Biology.

"The previous reproductive study only looked at the large eggs and broods," said PhD student and lead author Adam Reed.

This earlier work showed how females brood their young for up to 18 months, from "large yolky eggs" to "fully shelled young", and found that females can support as many as 70 young inside their hinged shell.

But concentrating on reproduction at a cellular level, Mr Reed and colleagues discovered that the eggs were actually present in males.

Continued:  http://www.bbc.co.uk/nature/19543557

Scary Mollusk Mouths Had Humble Beginnings

The inside of a mollusk's mouth is a fearsome sight to behold. Most mollusks, from giant squids to predatory slugs, have radulas, or tonguelike structures covered with interlocking teeth that move like a conveyor belt to slice and steer prey down the throat. But a new analysis of 500-million-year-old fossils suggests that the earliest radulas were used merely to slurp up mud-covered food from the seafloor.

University of Toronto graduate student Martin Smith had been examining hundreds of fossil specimens of the Cambrian animals Odontogriphus omalus, a naked slug, and Wiwaxia corrugata, a soft-bodied bottom-dweller covered with spines and scales. (The creatures would have lived at about the same time as an odd shrimplike creature that could grow up to 6 feet (1.8) in length and was equipped with spiny limbs on its mouth for snagging prey.)

Scientists had been unsure about where these animals fit in the evolutionary tree, whether they were members of the groups Mollusca, Annelida, or a group containing molluks and annelids. The basis for the confusion had to do with the organisms' bizzare mouthparts, which resembled both the radula of mollusks and the jaws of some annelid worms.

Read on:  http://www.livescience.com/22608-scary-mollusk-mouths-had-humble-beginnings.html

Who What Why: Are British slugs under threat?

A "super breed" of slugs has arrived from Spain, but are they a threat to the UK's native slugs?

The wet weather has resulted in myriad problems for people around the country and now there is another - it has helped a "super breed" of slug from Spain flourish in the UK.

Numbers of the creature commonly known as the Spanish stealth slug, Arion flagellu, are growing fast in the UK - helped by the wet weather - and threatening native molluscs, say experts in the field.

Another Spanish slug, Arion vulgaris, has already become a huge problem in Norway, attacking farms and gardens. Researchers fear the same could eventually happen in the UK.

Why the Spanish stealth slug poses such a problem is its aggressive breeding cycle. It produces hundreds more eggs than native slugs and so numbers multiply quickly. It also brings with it new diseases and parasites which can kill British slugs.

"It is a real concern," says Dr les Noble, a slug expert from Aberdeen University. "I have been collecting and analysing data on slugs for 30 years and it is clear to me that this incoming species is getting a foothold in the UK and spreading."

Their aggressive breeding cycle mean they lay around 400 eggs in a year, compared to the 100 or so laid by native species, says Dr Noble. Another problem is the diseases and parasites the slugs - which can grow to 10cm - carry.

"The Spanish stealth slug has evolved to deal with these diseases and parasites," says Dr Noble.

Continued:  http://www.bbc.co.uk/news/magazine-18672728

A New Species of 'Gigantic' Mollusc Has Been Discovered in the Antarctic Waters

ScienceDaily (Oct. 8, 2011) — Spanish researchers have discovered a rare mollusc in Antarctic waters that looks the same as limpets but is bigger in size than the species known to date. The specimen appeared in waters much further away from where this type of species is normally found.

A new species of mollusc that shares the same morphology as the limpet (Fissurellidae) and is 14 millimetres in length has been found in Antarctic waters. This discovery by a research team from the Ecology and Zoology Department of the University of Vigo, Spain has been published in The Nautilus and provides more information on the members of the Zeidora genus and their geographic distribution.
Cristian Aldea, co-author of the study, explains that "this genus belongs to a group which we know very little about. This group is made up of 14 species of which very few specimens have found."
Named Zeidora Antarctica, this 14 millimetre long specimen is much bigger than members of the same genus, who are not normally longer than 5 millimetres.

It was discovered at a depth of more than 600 metres in the Bellingshausen Sea in Antarctica -- a habitat with very different characteristics to that of other Zeidora species. Previously found specimens of this group live in tropical and warm waters. Out of all of them, eight species have been discovered in the Northern Hemisphere in the Caribbean, Japan, Panama and the Red Sea. Furthermore, six have been found in the Southern Hemisphere in places like the Galapagos Islands, Easter Island, Australia and New Zealand.

The specimen was found during the BENTART expedition of the Spanish National Antarctic Programme on board the Hespérides. Aldea recognises that he was not expecting "to find such a species on the trip since those that have already been discovered are known to be distributed from low (tropical) to medium latitudes with the closest becoming a species found in New Zealand."

Aldea states that "we carried out the description of the species based on the shell, given that no soft tissue could be found in the only caught specimen." These studies have allowed us to show, for instance, the number and size of ribs that the mollusc has. However, the morphology of its soft tissue was not revealed but "all of the characteristics taken from the shell indicate that it is a living species as opposed to a fossil species," according to the expert.

The discovered specimen is on display at the Madrid's National Natural History Museum (MNCN) and has been compared with other Zeidora naufraga Watson, Zeidora maoria Powell and Zeidora reticulata species that are on display at the London's Natural History Museum.
http://www.sciencedaily.com/releases/2011/10/111006084232.htm

Mass extinction victim survives! Snail long thought extinct, isn't

A view of Choccolocco Creek, Talledega County, Alabama, where a
surviving population of the wicker ancylid limpet Rhodacmea filosa
(insert, not to scale), was recently rediscovered.
Credit: Paul Johnson, Alabama Aquatic Biodiversity Center

June 1, 2011

ANN ARBOR, Mich.—Think "mass extinction" and you probably envision dinosaurs dropping dead in the long-ago past or exotic tropical creatures being wiped out when their rainforest habitats are decimated. But a major mass extinction took place right here in North America in the first half of the 20th century, when 47 species of mollusk disappeared after the watershed in which they lived was dammed.

Now, a population of one of those species—a freshwater limpet last seen more than 60 years ago and presumed extinct—has been found in a tributary of the heavily dammed Coosa River in Alabama's Mobile River Basin. Researchers from the University of Michigan, the Alabama Aquatic Biodiversity Center and the Kentucky State Nature Preserves Commission reported the rediscovery May 31 in the online, open-access journal PLoS One.

The story of Rhodacmea filosa's disappearance and reappearance is both a conservation success story and a cautionary tale for other parts of the world where rivers are being dammed, said Diarmaid Ó Foighil, professor of ecology and evolutionary biology and a curator at the U-M Museum of Zoology. It's also an example of how museum specimens collected generations ago can inform scientists of today.

Limpets are snails with shells shaped like caps rather than coils. They make their homes in the riffles and shoals of fast-flowing rivers and streams, where they graze on microscopic algae. When rivers are dammed, shoals and riffles are replaced with reservoirs, and the swiftly-moving water the limpets require is stilled.

The Mobile River Basin, a "global hotspot of temperate freshwater biodiversity," was extensively industrialized throughout the 20th century, and 36 major dams and locks were built. At the time, few thought much about preserving biodiversity. The prevailing attitude was, "What's not to like about getting electricity from a natural source—especially in impoverished, rural areas—and using that to drive industrialization?" Ó Foighil said. "The dams were seen as signs of progress."

But progress came at the expense of mollusks that were found only in that area and nowhere else in the world.

"Their habitat was destroyed in huge chunks," Ó Foighil said. The result: 47 of 139 endemic mollusk species were lost, representing a full one-third of all known freshwater mollusk extinctions worldwide.

Then, about 20 years ago, thanks to increased interest in and funding for conservation projects, biologists began searching patches of the drainage that weren't affected by damming, trying to find remnants of the original, rich fauna and save whatever still could be saved. At the Alabama Aquatic Biodiversity Center (AABC), a former catfish experimental research station has been converted into a captive breeding facility, with the aim of breeding survivors of the mass extinction and reintroducing them into unaffected parts of the watershed.

It was through those efforts that AABC director Paul Johnson discovered the surviving population of what he thought might be Rhodacmea filosa. But how does one definitively identify a species that hasn't been seen in decades? There are no other living members of the group with which to compare specimens.

That's where the U-M Museum of Zoology collection comes in. It just so happens that 100 years ago, biologists collected multitudes of mollusks from the Mobile River Basin—never envisioning the habitat destruction and resulting extinctions that were to come—and those specimens ended up in the U-M collection. Coincidentally, the mollusk portion of that collection was largely established by Bryant Walker, an early authority on—you guessed it—the limpet genus Rhodacmea. Furthermore, the last person to study Rhodacmea was a U-M graduate student, some 50 years ago.

Using century-old reference specimens, Ó Foighil, professor emeritus John Burch, graduate student Jingchun Li and collection coordinator Taehwan Lee were able to confirm the identity in addition to performing detailed morphometric and DNA analyses.

"This is very good news," Ó Foighil said. "With conservation biology, usually it's all gloom and doom, but this is one of those rare events where we have something positive to say."

But just because survivors have been found, does that mean the species can continue to survive?

"I think they can, because of two things," Ó Foighil said. "We have a persistent population in this little tributary, but we also now have in place the infrastructure for their captive breeding and reintroduction to other tributaries."

This snail tale might well serve as an object lesson, Ó Foighil said. "The industrialization of freshwater watersheds that happened across the U.S. in the last century is now happening all over the world. For instance, right now one of the most egregious examples is the ongoing damming of the Mekong, and there are likely thousands of endemic species there. Even though we're now more aware of this—of the negative downsides—when it comes to issues of economic development, freshwater biodiversity almost always loses."

In addition to Ó Foighil, Li, Lee, Johnson and Burch, the paper's authors include Ryan Evans of the Kentucky State Nature Preserves Commission. Funding was provided by the State Wildlife Grant Program, the U.S. Fish and Wildlife Service and the National Science Foundation.

http://ns.umich.edu/htdocs/releases/story.php?id=8426

Endangered gourmet sea snail could be doomed by increasing ocean acidity

Public release date: 25-May-2011

Increasing levels of ocean acidity could spell doom for British Columbia's already beleaguered northern abalone, according to the first study to provide direct experimental evidence that changing sea water chemistry is negatively affecting an endangered species.

The northern abalone--prized as a gourmet delicacy--has a range that extents along the North American west coast from Baja California to Alaska. Even though British Columbia's northern abalone commercial fisheries where closed in 1990 to protect dwindling populations, the species has continued to struggle, largely due to poaching.

To better understand the impact climate change — and specifically, increasing ocean acidity — has on this endangered species, UBC researchers exposed northern abalone larvae to water containing increased levels of CO2. Increases from 400 to 1,800 parts per million killed 40 per cent of larvae, decreased the size of larvae that did survive, and increased the rate of shell abnormalities.

"This is quite bad news, not only in terms of the endangered populations of abalone in the wild, but also the impact it might have on the prospects for aquaculture and coastal economics," says Christopher Harley, Associate Professor with the Department of Zoology and one of the authors of the study.

"And because the species is already thought to be limited by reproductive output and recruitment, these effects are likely to scale up to the population level, creating greater limits on population growth."

Average CO2 levels in the open ocean hover at 380 parts per million, a number which is excepted to increase slowly over the next century.

What concerns the researchers are the much higher spikes in dissolved CO2 that are already being observed along the BC coast, particularly in late spring and early summer when northern abalone populations are spawning.

The findings were published in the latest issue of the Journal of Experimental Marine Biology and Ecology.

"While we're looking at a single species that is culturally important as a source of food and artistic inspiration for many coastal Pacific Northwest First Nations, this information may have implications for other abalone species in other parts of the world," says Ryan Crim, lead author on the paper who conducted the research while a graduate student with the UBC Department of Zoology.

Other species of abalone are farmed around the world, principally in China, Taiwan, Japan and Korea. The black, white and pink abalone are also endangered on the west coast--red abalone are still an economically viable food species.

The study was funded by the Natural Sciences and Engineering Research Council of Canada and conducted in collaboration with the Bamfield-Huu-ay-aht Community Abalone Project, a small abalone hatchery in Bamfield which has subsequently gone out of business. The dual mission of the hatchery was to produce cultured abalone for high end restaurants, and to restore endangered abalone by culturing and releasing larvae and juveniles to the wild.

Harley and Crim will continue to work with the aquaculture industry to study the effects of acidification on oysters and other shellfish.

http://www.eurekalert.org/pub_releases/2011-05/uobc-egs052511.php

Rock-eyed sea creature

This lined chiton, whose anterior end is to the right, lives about
50 feet below the water's surface near Whidbey Island, Washington.

Tuesday, April 19, 2011

A tiny sea mollusk uses eyes made of a calcium carbonate crystal to spot predators lurking above, researchers say of the first such rocky lenses found in the animal kingdom.

While scientists had discovered the hundreds of eye-like structures on the surface of this armored mollusk, called a chiton, decades ago, they didn't know what they were made of or whether they could actually see objects or just sensed light.

"Turns out they can see objects, though probably not well," said study researcher Daniel Speiser, who recently became a postdoctoral fellow at the University of California, Santa Barbara.

http://www.thedailystar.net/newDesign/news-details.php?nid=182144

Oysters Are 'Functionally Extinct'

The Huffington Post
Dean Praetorius
First Posted: 02/ 4/11 04:21 PM

Oysters aren't disappearing from the dining table anytime soon, but they may be disappearing from our oceans.

A recent study published in BioScience has shown that the mollusks, declared "functionally extinct," are disappearing quickly as 85 percent of their reefs have been destroyed through disease or over-harvesting, according to the AFP. 75 percent of the remaining wild oysters can be found in 5 locations in North America.

So what does "functionally extinct" mean?

Oysters no longer play almost any significant role in their ecosystems.

From the AFP:

"Oyster reefs are at less than 10 percent of their prior abundance in most bays (70 percent) and ecoregions (63 percent)," said the study.

"They are functionally extinct -- in that they lack any significant ecosystem role and remain at less than one percent of prior abundances in many bays (37 percent) and ecoregions (28 percent) -- particularly in North America, Australia and Europe."

While the study didn't include parts of South Africa, China, Japan, North Korea, and South Korea, other studies suggest that there's been a significant decrease in oysters in these regions as well, according to the authors.

http://www.huffingtonpost.com/2011/02/04/oysters-are-functionally-_n_818870.html

Researchers say 21 pct of freshwater species in northern Africa threatened with extinction

By Associated Press
8:52 a.m. EDT, September 7, 2010

STOCKHOLM (AP) — Researchers at an international water conference in Stockholm said that 21 percent of freshwater species in northern Africa are threatened with extinction.

Scientists from the International Union for Conservation of Nature presented a new report on Tuesday, which shows more than 1,000 fish, crabs, mollusks, aquatic plants and insects in northern Africa are in danger.

The IUCN said agriculture, water abstraction and dams are the biggest threats to these species, and urged governments to better manage their water resources.

The report summarizes the findings of 200 scientists, who had worked for five years to assess a total of 5,167 African freshwater species.

http://www.orlandosentinel.com/news/space/sns-ap-eu-sweden-african-species,0,7467007.story

Scientists find new invasive fresh water clam species in Lake George

RIGHT: Asian clam (Corbicula fluminea)

August 30, 2010

Scientists find new invasive fresh water clam species in lake George

(PhysOrg.com) -- The new species (Corbicula fluminea) was located in the Village of Lake George and poses a serious threat to native mussels and the Lake George ecosystem, according to Sandra Nierzwicki-Bauer, director of the Rensselaer Darrin Fresh Water Institute.

The Rensselaer Polytechnic Institute Darrin Fresh Water Institute (DFWI) has discovered a new invasive fresh water clam species in Lake George. This species, found last week by DFWI student Jeremy Farrell, was located in the Village of Lake George and poses a serious threat to native mussels and the Lake George ecosystem, according to Sandra Nierzwicki-Bauer, director of DFWI.

Nierzwicki-Bauer said the species - Corbicula fluminea - is an invasive clam from Asia, capable of self fertilization, achieving densities of thousands per square meter, and crowding native species from their typical habitats. Commonly known as the Asian clam, it is a light brown triangular clam that can survive in fresh and brackish waters. If the invasion is a localized one, it may be possible to eradicate, she added. The dominant native mussel in Lake George is Elliptio complanata.

“It is imperative that we move quickly to determine the extent of this infestation to assess the best treatment options that can be undertaken immediately,” said Nierzwicki-Bauer, who is also a professor of biology at Rensselaer. “We have reached out to the regulatory agencies to assess all our options.”

The Lake George environmental organizations have contracted to bring in an expert in invertebrate biology and scientific SCUBA: Dan Marelli, from Florida. He has worked with DFWI scientists for over 15 years to help coordinate SCUBA surveys, and he will direct new surveys that will be carried out by FUND for Lake George, DFWI, Bateaux Below Inc., and volunteer divers. Immediate plans include a survey of the shallow and embayment areas to establish the extent of infestation. Possible eradication or management strategies include use of a benthic barrier, essentially a plastic mat that could “smother” the clams, suction harvesting, or a combination of these methods. Currently, benthic mats are being used on a one-acre area in Lake Tahoe, Calif., to help manage the infestation there. Preliminary field work by DFWI staff indicates that a minimum of 2.5 acres in Lake George is infested.

The environmental groups will be coordinating with the Adirondack Park Agency and the New York Department of Environmental Conservation.

An initial plan of action has been organized to complete a SCUBA survey during the next two weeks to determine the geographical range of the infestation. This will involve surveys by divers of the lake bottom sediment. Other nearby areas with suitable habitat will be surveyed soon. Initial surveys will be supervised by Marelli. Once the extent of the infestation has been quantified, either a management or eradication strategy will be determined. The initial survey work will utilize the eight-diver crew of Aquatic Invasives Management (AIM) of Lake Placid, which is currently working in Lake George on management of Eurasian watermilfoil, under a contract with the FUND for Lake George.

Peter Bauer, executive director of the FUND for Lake George, said, “This is the newest invader to be found in Lake George. We’ve long had Eurasian watermilfoil and curlyleaf pond weed, as well as zebra mussels. We’ve seen a few plants of Brittle Naiad, too. We don’t know the current extent of the Asian clam infestation, but if we’re lucky maybe this is an isolated infestation in Lake George that we caught early.”

Once field investigations are completed, further information on the extent of the infestation will be provided.

“It is now most important that we pull together with other organizations and the public to mount a rapid and effective response to this disturbing discovery,” said Bruce E. Young, chairman of the Lake George Park Commission. “The community should be reassured that steps are under way to assess the extent of the Asian clam colony and if possible, eradicate it.”

“While the discovery of an established Asian clam population in the lake was not good news to hear, the good news is that all the groups involved are taking swift action and rallying the troops. We are all divvying up the tasks, and LGA is heading up public outreach. It is very important to spread the word to area boaters and business owners, as we do not want the clam to spread further within our own lake or to other nearby bodies of water as well. We will be providing educational materials about the Asian clam and its spread to boaters, businesses, and residents all around the lake in the next few days,” said Walt Lender, executive director, Lake George Association.

“It will take a concerted partnership effort to address Asian clam in Lake George. Key partners have already begun the rapid response process to survey, evaluate, and determine feasible control and spread prevention options. The Lake Champlain Basin Program will assist management efforts in any way possible as this species affects not only Lake George but the entire Lake Champlain Basin watershed and beyond,” said Meg Modley, Aquatic Invasive Species management coordinator, Lake Champlain Basin Program.

Background on Corbicula fluminea

Asian clams (Corbicula fluminea) are native to South East Asia and were first documented on the west coast of the United States in 1938. Since then they have spread to over 40 states. Asian clams are small, averaging less than 25mm (1.5 inches) with an oval triangular shape, deep at the hinge. Its outer shell is yellow brown, light brown to black with distinctive elevated, evenly spaced concentric ridges on the surface.

The Asian clam is a very hardy and persistent freshwater mollusk, capable of rapid growth and spread. The Asian clam prefers to colonize on sandy substrates in quiet, warmer, sunlit waters, and can be found with one-third of its shell protruding above the substrate (although it has been found at water depths to 250 feet and within the sediment buried up to 7 inches in Lake Tahoe). Asian clams can form dense clusters, with up to 5,000 animals per square meter. Asian clams are able to withstand freezing conditions, but their ability to reproduce decreases with exposure to lower temperatures (below 10oC/50oF). For a long time, New England was considered environmentally inhospitable to the Asian clam.

The Asian clam is hermaphroditic and therefore capable of self-fertilization. A single clam can release over 400 offspring per day, depending on the conditions. The microscopic pediveligers (the final veliger or larval stage) travel along the substrate to a new location, attaching with byssus fibers to any available suitable substrate. The young that are hatched in the spring usually attain maturity by the fall (at 6-10 mm) and live an average of two to four years, with a maximum life span of seven years.

Geoffrey Schladow, director of the Tahoe Environmental Research Center of the University of California, Davis, said the Asian clams promote so much algae growth that they can turn some waters from blue to green. As they filter the water and consume plankton, they deposit high concentrations of nutrients in their excretions. Another significant impact of the Asian clams infestations is the “biofouling” or the impairment or degradation of intake pipes for power plants and drinking water treatment systems.

Provided by Rensselaer Polytechnic Institute (news : web)

http://www.physorg.com/news202399687.html

Snails on crystal meth: The facts

Profs spend days poking hopped-up molluscs with sticks

By Lewis Page
Posted in Biology, 28th May 2010 14:27 GMT

In a development whose importance it would be difficult to exaggerate, scientists have produced research answering one of the great questions facing humanity in the 21st century: what happens if you get snails hopped up on crystal meth and poke them with sticks?

The drug-pushing scientists in question are Barbara Sorg of Washington State Uni and Ken Lukowiak of the University of Calgary. The mollusc they chose for their experiments was the pond snail Lymnaea stagnalis.

The two snail savants placed their slimy drug-slaves into pond water which they had spiked with methamphetamine, described as "a highly addictive drug that seduces victims by increasing self-esteem and sexual pleasure, and inducing euphoria".

Having got their slippery subjects well addled on this delightful but damaging chemical treat, Sorg and Lukowiak then tested their memories by means of varying the amount of oxygen in the pondwater and poking them with sticks.

Perhaps we should explain. Low oxygen levels often occur in normal outdoor ponds not laced with illegal narcotics, and in this case the local L stagnalis will extend their "pneumostomes" (breathing tubes) above the surface to get more life-giving oxy.

However, it is possible to train them not to do this by sitting next to the pond or lab tank and poking any suffocating snail which dares to wave its squelchy snorkels. This is actually a standard, widely-used method among biologists for testing snails' intellectual powers.

After a lengthy and painstaking period of sitting in the lab poking snails immersed in various different mixtures of pondwater and drugs, Lukowiak and Sorg report that in fact methamphetamine makes snails' memories much better. According to a statement issued on their behalf:

Memories formed under the influence of meth seem to be harder to forget, possibly because the drug disrupts the mechanisms for forgetting, and could help us to understand how amphetamines enhance memory in humans.

The research is to be published in the Journal of Experimental Biology. Sorg and Lukowiak have previously carried out similar studies involving snails on cocaine. ®

http://www.theregister.co.uk/2010/05/28/snails_on_crystal_meth/

Florida on guard against giant snails

PHOTO: J.M.Garg

Efforts are underway to prevent the reestablishment of African mollusks, which threaten crops and public health.

March 14, 2010 By Anthony Colarossi

Reporting from Orlando, Fla. — They're not as menacing as Burmese pythons proliferating in the Everglades, but giant African snails are targets of the government too.

The invasive mollusks are considered a major plant pest and a potential public health threat because they can spread diseases, including meningitis. Now federal and state authorities are seeking to prevent the large, slimy, shell-toting snails from reestablishing themselves in Florida.

Once established, agricultural officials said, the mollusks "can create a giant swath of destruction."

"The idea is that these are prolific breeders," said Mark Fagan, spokesman for the Florida Department of Agriculture and Consumer Services. "Our primary concern is the potential harm it can do to agricultural crops, as well as [public] health concerns."

The Florida department, the U.S. Department of Agriculture and the U.S. Fish and Wildlife Service are leading the mollusk-prevention effort.

Known as Achatina fulica, the species is one of the world's largest land snails. They can grow to 8 inches long and 4.5 inches in diameter. It is illegal to import the snails into the United States without a permit.

The snail has not been an issue in Florida for several decades. In 1966, a child smuggled three snails into the Miami area as pets. His grandmother later released them into a garden, and by 1973, the population had grown to more than 18,000, officials said.

Over the next decade, officials spent more than $1 million to eradicate them. That effort is considered the only successful giant African snail eradication on record.

Scientists say the snails consume at least 500 kinds of plants, including citrus crops, Fagan said.

They also can damage buildings by consuming plaster, stucco and other materials they need to grow their shells.

They carry parasites and worse. "These snails are known to carry meningitis bacteria, so it's also a health concern," Fagan said.

The snails are identified by seven to nine whorls, or spirals. They have a brownish shell covering half the length of their bodies. They live as long as nine years and have female and male reproductive organs.

After mating, each snail can produce 100 to 400 eggs. Mated adults lay about 1,200 eggs a year.

The snails originate in East Africa. Officials say they have been introduced into Caribbean islands such as Martinique and Guadeloupe, and they have been detected in Saint Lucia and Barbados.

Fagan said multiple snails were found in February at one property in Hialeah, Fla. Authorities searched the nearby area, but no other snails turned up, he said.

Last year, state and federal wildlife officials began a concerted effort to prevent the spread of pythons in and around the Everglades because those invasive reptiles prey on native species.

Fagan said it's difficult to compare the dangers posed by two species. "The snakes pose a completely different threat to nature," he said. "I don't think you can compare the two."

http://articles.latimes.com/2010/mar/14/nation/la-na-giant-snails14-2010mar14
(Submitted by D.R. Shoop)

Sex and the Single Snail

Study shows benefits of sexual reproduction over asexual.

By Fariss Samarrai
28 January 2010

Why have sex?

That is one of the big questions in evolutionary biology.

Sexual reproduction is a high-energy endeavor, requiring, often, the quest for a mate, the actual act of sex, and the carrying of offspring (almost always by the females).

Why not reproduce asexually? Many organisms do, though most of them are single-celled bacteria and other simple life forms. Still, some multicellular organisms also reproduce asexually, including many plants, insects, some reptiles, various mollusks and a few fishes.

This highly efficient mode of reproduction is a low-energy endeavor, requiring no search for a mate, no sexual act, and sometimes, no carrying of offspring. It also allows rapid and abundant proliferation, since all members of that population are female and able to produce offspring.

So, yes, why have sex?

The prevailing theory is that sexual reproduction, which requires two genders, allows genetic intermingling that overall is very good for both the individuals and the species as a whole.

Asexual reproduction, on the other hand, is largely static, where each offspring is genetically identical to every other. This allows for the ongoing accumulation and replication of harmful mutations and little room for adaptation to rapidly changing environments, such as the introduction or quick proliferation of a pathogen. This could, in the long run, lead to extinction of the species.

A new study, by researchers at the University of Virginia and the University of Iowa, published currently in the journal Molecular Biology and Evolution, provides additional credence to this understanding.

“We demonstrated that sexual reproduction allows organisms to clean deleterious mutations from their genome,” said U.Va. biology professor Doug Taylor, who co-authored the study. “Asexual reproduction does indeed allow for the accumulation of deleterious mutations.”

Taylor and his colleagues at Iowa sequenced the entire mitochondrial DNA of multiple sexual and asexual lineages of a species of snail, Potamopyrgus antipodarum, which has sexual and asexual individuals living side-by-side in lakes in New Zealand.

They found that the sexually reproducing variety accumulates harmful mutations in DNA at about half the rate of the asexual lineage. This does not mean that mutations occur at a slower rate, but that, when mutations do occur, they are cleaned from the genome twice as fast in the sexual lineage.

“Asexual lineages suffer from the fact that they can’t clean the mutations from the genome—that’s the theory,” Taylor said. “And we found that, indeed, the sexual lineages are able to purge the genome of their deleterious mutations much more effectively than the asexual lineages.”

Taylor said the finding might be a profound demonstration, at the genetic level, for why sexual reproduction exists in the first place.

Taylor and his colleagues looked for mutations in the snails’ mitochondrial genome, in part because the mitochondrial genome is small and evolves rapidly in most animals. However, the mitochondrial genome is also where many mutations are known to affect the overall health of the full organism.

Underlying genetic disorders in the mitochondria are believed to cause many diseases affecting organisms, such as—in humans—Parkinson’s disease, premature aging, optic neuropathies and muscular degenerative disorders.

http://news.clas.virginia.edu/x16422.xml
(Submitted by T. Peter Park)

Attack of the zebra mussels

Broadcast Date: July 6, 1990

The ecological balance of the Great Lakes is at risk thanks to the infestation of zebra mussels (Dreissena polymorpha), an exotic freshwater shellfish native to the Caspian Sea region of Asia. The mussels are believed to have been introduced into the Great Lakes system in the 1986 by intercontinental freighters along the St. Lawrence Seaway. Now, they number in the billions (each female can produce as many as 40, 000 eggs) and are changing the ecology of the Great Lakes by filtering microscopic life from the water.

They're also causing havoc by sinking buoys and sticking by the thousands to water intake pipes, thus threatening water supplies for millions of Canadians. The mussels lay their eggs near the pipes of electric generating stations and when a large population develops, the pipes often become clogged and unusable. In this CBC Television clip, Midday talks to Gerry Mackie, a zoologist at the University of Guelph, about the potential long-term damage of these tiny invaders.

• Zebra mussels caused millions of dollars in damage to boats and power plants in Canada and the United States, forcing scientists to investigate ways to combat them. Researchers at Purdue University came up with an interesting and effective method: radio waves. Scientists at the Indiana-based University used low-energy radio waves to zap the mussels. They exposed 1, 000 mussels in giant fish tanks to the radio waves. All of the mussels died within 40 days.
  
• A study conducted in 2001 at Laval University discovered that the mussels were not only transported into the Great Lakes by intercontinental boats, but also attaching themselves to aquatic weeds that get entangled on the bottom of local recreational boats and boat trailers.
  
• The study showed that zebra mussels have up to seven ways of attaching themselves for transport: to the boat's exterior, anchor, entangled aquatic weeds, engine cooling system, bilge water, live wells, bait buckets. The study concluded that it wasn't necessarily the number of recreational boats on a lake, but instead the regularity of ‘promiscuous' behaviour that contributes to the severity of zebra mussel infestation.

See video at: http://archives.cbc.ca/science_technology/natural_science/clips/3525/&ref=rss

Sea mollusks taste their memories to build shells

By Robert Sanders, Media Relations | 01 April 2009

BERKELEY — University of California, Berkeley, graduate student Alistair Boettiger has amassed a beautiful collection of seashells, but not by combing the beach. He created them in his computer.

He and George Oster, a UC Berkeley biophysicist, along with University of Pittsburgh mathematical neuroscientist Bard Ermentrout, have written a computer program that generates the complex patterns of seashells using simple principles developed to explain how the brain works and how memories are stored.

The "neural net" model explains how mollusks build their seashells based on the finding that the mollusk's tongue-like mantle, which overlaps the edge of the growing shell, senses or "tastes" the calcium carbonate layer laid down the day before in order to generate a new layer.

"The pattern on a seashell is the mollusk's memories," said Oster, a professor of environmental science, policy and management and of molecular and cell biology. "The shell is laid down in layers, so the mantle is sensing the history of the mollusk's 'thoughts' and extrapolating to the next layer, just like our brains project into the future."

The studies may help neuroscientists understand how neural networks work in the brain and throughout the body, where neural nets cover our skin and all internal organs.

Full article and photos at: http://www.berkeley.edu/news/media/releases/2009/04/01_seashells.shtml