The blue-rayed limpet is a finger nail-sized mollusc that lives in kelp beds and is distinguished by the bright blue dotted lines that run in parallel along their translucent shells.
Scientists at MIT and Harvard University have now identified two optical structures within the limpet’s shell that give its blue-stripped appearance that can be quite brilliant when light hits at the right angle.
They say these natural optical structures could be used as a basis for developing colour-selective, controllable, transparent displays that require no internal light source and could be incorporated into glass and windows.
“Let’s imagine a window surface in a car where you obviously want to see the outside world as you’re driving, but where you also can overlay the real world with an augmented reality that could involve projecting a map and other useful information on the world that exists on the other side of the windshield,” said Mathias Kolle, assistant professor of mechanical engineering at MIT. “We believe that the limpet’s approach to displaying colour patterns in a translucent shell could serve as a starting point for developing such displays,” he added.
The findings, reported in the journal Nature Communications, represent the first evidence of an organism using “mineral structures” to produce optical displays. While birds, butterflies and beetles can also display brilliant blues, they do so with “organic structures” such as feathers, scales and plates.
The molluscs, which are also found on the coasts of Norway, Iceland, Portugal and the Canary Islands, first came to Dr Kolle’s attention when his brother, Stefan, of Harvard, brought him a few of the organisms in a small container.
The pair were struck by the molluscs’ brilliant patterning and decided to study their optical properties.
They assembled a team of researchers to do a detailed structural and optical analysis of the shells. They discovered that the zig-zag pattern on the blue-rayed limpet acts as a filter reflecting only blue light.
As the rest of the incoming light passes through the shell, the underlying particles absorb this light – an effect that makes a shell’s stripes appear even more brilliantly blue.
“It’s all about multifunctional materials in nature: Every organism – no matter if it has a shell, or skin, or feathers – interacts in various ways with the environment and the materials with which it interfaces to the outside world frequently have to fulfil multiple functions simultaneously,” said Dr Kolle.
“Engineers are more and more focusing on not only optimising just one single property in a material or device, light a brighter screen or higher pixel density, but rather on satisfying several design and performance criteria simultaneously,” he added.
Technology has a long history of borrowing from nature. The redesigned nose of the Shinkansen Bullet Train in Japan took inspiration from the kingfisher, a fish-eating fowl that creates barely a ripple when it darts into water in search of a meal.
The train’s 50ft-long “kingfisher” nose helped overcome the problem of noise pollution – previously as the high speed train drove through tunnels, air pressure had built up in waves and when the nose emerged, it produced a thunderclap heard for a quarter of a mile.
Meanwhile, the Namibian Beetle raises its back into the air as fog rolls into its desert habitat. Bumps on its shell catch water droplets, which then run down chutes toward its mouth.
The “Dew Bank Bottle” imitates the beetle’s water-collection system. Morning dew condenses on it and conveys it to the bottle, which has a drinking spout.
- Mollusc, found in Java, is between 430,000 and 540,000-years old
- Shell has a polished edge as well as a zigzag pattern of grooves
- This suggests it was used as an ancient tool for cutting and scrapping
- Earliest previously known engravings are at least 300,000 years younger
- Find implies that Homo erectus was also capable of 'modern' behaviour
The oldest known shell to have been engraved by an early human has been uncovered in a Dutch museum collection, where it remained unnoticed since the 1930s.
The ancient mollusc, originally discovered on the island of Java, is between 430,000 and 540,000-years-old, dating to the time Homo erectus inhabited the remote volcanic outpost.
The engravings resemble the previously oldest-known etchings, which were created by either Neanderthals or modern humans around 100,000 years ago.
The shell has a polished edge and a zigzag pattern of engravings, suggesting it was used from cutting or scraping.
If this is the case, it means our ancestors, Homo erectus, were more intelligent than we thought.
The successful, long-lived species emerged out of Africa almost two million years ago, and were possibly the first early humans to live in hunter-gather societies they also used rafts to travel the oceans.
'It rewrites human history,' Dr Stephen Munro, a Australian National University paleoanthropologist who made the find, told Business Insider.
'It's evidence that Homo erectus exploited these aquatic food resources, and fits with other evidence that they probably foraged in and around water.'
Geometric engravings are considered to be a sign of modern cognitive abilities, but the origins of such behaviour have been debated.
The latest analysis of freshwater mollusc shell collected from the Trinil fossil site on Java in the 1890s imply Homo erectus was also capable of 'modern' behaviour.
The team found that Homo erectus were able to open the shells by drilling a hole through the shell with a shark's tooth.
This damaged the muscles causing the valves of the shell to open, so that the contents can be eaten.
Dr Josephine Joordens, of Leiden University in The Netherlands, said: 'The manufacture of geometric engravings is generally interpreted as indicative of modern cognition and behaviour.
'Key questions in the debate on the origin of such behaviour are whether this innovation is restricted to Homo sapiens and whether it has a uniquely African origin.
'Here we report on a fossil freshwater shell assemblage from the main bone layer of Trinil - the type locality of Homo erectus discovered by Eugene Dubois in 1891.
It may look like a cross, but lines scratched into a cave wall could be proof that Neanderthals were more intelligent and creative than previously thought.
The cross-hatched engravings inside Gorham's Cave in Gibraltar are the first known examples of Neanderthal rock art.
The find is significant because it indicates that modern humans and their extinct cousins shared the capacity for abstract expression, according to a team of scientists who studied the site.
Experts examined and described the grooves in a rock that had been covered with sediment in the study published in the PNAS journal.
Archaeologists had previously found artefacts associated with Neanderthal culture laid over the top of the artwork, suggesting that the engravings must be older, said Professor Clive Finlayson, director of heritage at the Gibraltar Museum.
'The production of purposely made painted or engraved designs on cave walls is recognised as a major cognitive step in human evolution - considered exclusive to modern humans, he said.
'In the Dubois collection in the Natural History Museum in Leiden we found evidence for freshwater shellfish consumption by hominins, one unambiguous shell tool and a shell with a geometric engraving.
'Together our data indicate the engraving was made by Homo erectus and it is considerably older than the oldest geometric engravings described so far.
'Although it is at present not possible to assess the function or meaning of the engraved shell this discovery suggests that engraving abstract patterns was in the realm of Asian Homo erectus cognition and neuromotor control.'
The ability to make and use tools dates back millions of years. Chimpanzees - our closest living relatives - can devise spear-like weapons for hunting and create specialised tool kits for foraging ants.
This suggests our family tree could have possessed wooden tools since the ancestors of humans and chimps diverged some four million years ago.
A species of mussel which is threatening to block water supplies to a US city has been found in the UK.
Quagga mussels have been discovered at Wraysbury reservoir, near Heathrow Airport, the Wildfowl and Wetland Trust (WWT) said.
The molluscs form large colonies on hard surfaces and can block pipes and cause flooding, the trust said.
The Department for Environment, Food and Rural Affairs said it would take action to tackle the threat.
Some scientists say the mussel poses the maximum risk to the UK environment of any non-native species.
The 4cm (1.5in) bivalves originated in Ukraine and spread across Europe as new canals opened, a WWT spokesman said. They were introduced to the US by ships discharging their ballast in the Great Lakes.
- The species originates from an area around the Black and Caspian seas
- Quagga mussels feed on different varieties of algae
- There is no effective eradication method once it has been established in a reservoir
- The quagga mussel can be hard to distinguish from the zebra mussel, which is already widespread in England and Wales
- Quagga and zebra mussels have spread to 29 states in the USA
- They are found in the Great Lakes and the Mississippi river basin as well as in artificial channels including in the Chicago area
Sources: Environment Agency and the National Wildlife Federation
The species is flourishing in Lake Mead, formed by the Hoover dam, and engineers are working to stop them colonising the dam's turbines and blocking the pipes which supply water to Las Vegas, the spokesman said.
Earlier this year a group of scientists at the Centre for Ecology and Hydrology (CEH) identified the quagga mussel as the single greatest threat to the UK's wildlife of any alien species.
Dr Helen Roy, one of the scientists involved in the research, said that, after looking at hundreds of species from all over the world, the quagga mussel was the most likely to arrive and establish itself in the UK and pose a danger to biodversity there.
Sarah Chare, from the Environment Agency, said the quagga mussel affected water quality as well as clogging up pipes.
The Department for Environment, Food and Rural Affairs (Defra) said it would be working to reduce the risks of the quagga mussels spreading any further.
A spokesman said: "It is important that we take action to address the threats posed by invasive non-native species.
"Users of our waterways can help with this by checking their equipment and keeping it clean and dry."
A Wildfowl and Wetlands Trust spokesman said the trusts's London Wetland Centre, downstream from Wraysbury "is the sort of place [where] they'll wreak havoc with the wildlife, if left unchecked".
Jeff Knott, from the WWT, said: "These tiny mussels can be devastating but look so innocuous.
"Quagga mussels are likely to indirectly cause suffering and death for hundreds of thousands of native animals, fish and plants and cost millions of pounds in tax and water bills to protect drinking water supplies."
Molluscs, or mollusks, are an important phylum of invertebrate animals. Most of them are marine. They have huge numbers in-shore, that is, in shallow waters near the shore. They are the largest marine phylum, with about 93,000 recognised species, 23% of all named marine organisms. They also occur in freshwater and on land.
Molluscs are extremely varied: they have great diversity. That may be why there is no word in English for the phylum as a whole. "In an evolutionary sense, molluscs are plastic material".[1]
Most molluscs have shells, but some groups do not: octopods, slugs, and thegastropods known as sea slugs. There is great variety in the phylum, much more so than their ancient rivals, the brachiopods
Classes of molluscs:
- Cephalopods: Squid, Octopus
- Gastropods: whelks, limpets, snails, slugs, Nudibranchs
- Bivalves: Most shellfish; clams, oysters, scallops, mussels
- Scaphopoda: the tusk shells
- Polyplacophora: Chitons
- Monoplacophora:
- Aplacophora: worm-like molluscs
- Helcionelloida
As applied to mollusks, the New Latin termdiverticulum is an anatomical feature. The term is most often encountered in the plural form as "diverticula", "hepatic diverticula", or "digestive diverticula", which are anatomical terms for organs which are visible from the outside of the body in a clade of sea slugs known as aeolid nudibranchs, marineopisthobranch gastropod molluscs.[1]
The term is also applied to mollusk anatomy in other contexts: land slugs such as Lehmannia marginata have a caecal diverticulum [3] and there is also a diverticulum in the stomach of certain Bivalvia
The Bivalvia, in previous centuries referred to as the Lamellibranchiata andPelecypoda, comprise a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. They have no head, and they also lack a radula. Bivalves include clams, oysters, cockles,mussels, scallops, and numerous other families that live in saltwater, and well as a number of families that live in freshwater. The majority are filter feeders. The gillshave evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. A few bore into wood, clay or stone and live inside these substances. Some bivalves, such as the scallops, can swim.
The shell of a bivalve is composed of calcium carbonate, and consists of two, usually similar, parts called valves. These are joined together along one edge (the hinge line) by a flexible ligament that, usually in conjunction with interlocking "teeth" on each of the valves, forms the hinge. This arrangement allows the shell to be opened and closed without the two halves becoming disarticulated. The shell is typicallybilaterally symmetrical, with the hinge lying in the sagittal plane. Adult shell sizes of bivalves vary from fractions of a millimetre to over a metre in length, but the majority of species do not exceed 10 cm (4 in).
Bivalves have long been a part of the diet of coastal human populations. Oysters were cultured in ponds by the Romans, and mariculture has more recently become an important source of bivalves for food. Modern knowledge of molluscan reproductive cycles has led to the development of hatcheries and new culture techniques. A better understanding of the potential hazards of eating raw or undercooked shellfish has led to improved storage and processing. Pearl oysters (the common name of two very different families in saltwater and freshwater) are the most common source of natural pearls. The shells of bivalves are used in craftwork, and the manufacture of jewellery and buttons. Bivalves have also been used in the biocontrol of pollution.
Bivalves appear in the fossil record first in the early Cambrian more than 500 million years ago. The total number of living species is approximately 9,200. These species are placed within 1,260 genera and 106 families. Marine bivalves (including brackish water and estuarine species) represent about 8,000 species, combined in four subclasses and 99 families with 1,100 genera. The largest recent marine families areVeneridae, with more than 680 species and the Tellinidae and Lucinidae, each with over 500 species. The freshwater bivalves include seven families, the largest of which is the Unionidae, with about 700 species.
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