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Design, Naturally: Lateral lines provide a sixth sense for underwater robots

By Anwen Bowers

More little fish swimming in a school.
“We turning left now?” “Yeah, you do know we have a sophisticated biological mechanism for finding that out, right?” “I was just asking for a friend” | Image: Tom Thai

Have you ever seen two fish bump into each other?

The underwater world is an assault of sensory signals. Sound, for example from crashing waves, travels over twice as fast in water than it does in air. Smells, ranging from mating hormones to decaying organisms, clash against each other like instruments in an orchestra and would be overwhelming to us if we had noses sensitive enough to detect them. Light is changing constantly, with the different wavelengths becoming increasingly filtered out with depth until animals are left navigating waters so dark that they would be impossible to penetrate with human eyes.

But despite the chaos, fish are able to identify predators, prey and potential mates with lightning reflexes and take the appropriate action within milliseconds.  This is thanks to a super-human sensing mechanism called the lateral line, which gives the fish a sixth sense with which to navigate in their watery habitat.

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A subtle stripe of hair can tell fish everything they need to know about their environment | Image: Pogrebnoj Alexandroff

Sometimes visible as a dark strip running along the fish from fin to tail, the lateral line consists of minuscule bundles of hair that can be either attached to the surface of the scales or slightly submerged in channels below the skin. These hairs work similarly to whiskers on a cat, bending in response to any change in the flow of water around the fish. Cells at the base of the hairs then send messages to the brain, containing information on the scale, speed, and direction of the disturbance. This can then be interpreted to give information about the size and shape, and therefore species and likely friendliness, of anything moving in the local area. The ability to identify friend from foe by the flick of its tail is an invaluable tool of survival.

Seas and oceans are one of the least understood habitats on earth, with vast areas being simply too inaccessible to explore. As space on land is becoming rapidly exhausted, we are extending further and deeper into the oceans to source food, generate energy and hunt for new minerals and medicines. Faced with challenges such as the extreme pressure and low temperatures, increasingly we are depending on the work of underwater robots to bring us information on the chemistry, physics, and biology of the deep sea.  Engineers looking to improve the performance and capabilities of these underwater robots have found inspiration in the lateral line to improve the performance of these robots.

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Bass-ta la vista, Ray-by: artificial lateral lines have inspired highly sensitive robotic fish | Image: Titus 140

Researchers in Germany and the US have independently come up with two different systems that recreate the processes that take place in the lateral line hairs. Integrated into underwater robotic technology, these systems could create a robot with much greater perceptions of their surroundings. Traditionally, operators would rely on images from video and sonar to navigate and direct the actions of the robot underwater. Both of these technologies are limited, as they can only provide information on the small area that they are pointing at Imagine only being able to view the world through a toilet roll tube – it’s a bit like that.

Lateral lines could provide a much more detailed 3D picture of the surrounding environment, allowing more informed decisions about how the robot should proceed. The more information available about the surrounding area, including any obstacles, the greater the chance of the robot completing its mission as efficiently and safely as possible. For example, if the battery is running low, the lateral line would be able to identify nearby areas of low water movement where the robot can go to rest and conserve energy out of the current. Taking inspiration from nature, and building robots that can sense like fish, scientists can expect to soon be announcing plenty more exciting discoveries from the mysterious deep ocean.

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Design, Naturally: Precious pearls inspire super-strong glass

By Anwen Bowers

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The Duke of Buckingham’s frankly over-the-top bling held some fascinating material properties. | Image: Art Gallery of South Australia

Take a stroll through almost any art gallery and the cultural value of pearls as a status symbol through time is inescapable. From the intricately laced clothes in Elizabethan portraits to the long strings worn by chic youth in the early 20th century photographs, pearls have been a symbol of wealth and glamour. However, shifts in technological capabilities mean that pearls could soon have a much broader range of uses than being merely decorative.

Starting life as a humble piece of grit, pearls gain their ethereal shimmer from nacre, a biological substance secreted by oysters, which eases the discomfort once grit enters their shells. Nacre is produced by a number of different molluscs, and can also be found inside snail shells and coating mother-of-pearl. This material has long been of interest to materials scientists due to its incredible toughness.

Scanning electron microscopy has been used to reveal that the structure of nacre is similar to that of a brick wall, with “bricks” in the scale of micrometres being glued together by an organic adhesive. The bricks themselves are made of aragonite, a form of calcium carbonate with a similar structure to sea shells.  These bricks overlay each other, and when pressure is applied they are able to slide against each other which prevents the material from snapping. If any cracks form in nacre then the adhesive acts as a barrier, dissipating the energy along the channels between the bricks and preventing the crack from propagating through the material.

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Layers of aragonite, held together with a natural glue, make up the intricate structure of nacre. New techniques are developing super strong glass from man-made nacre, or ‘facre’ if you will | Image: Fabian Heinemann

This structure gives nacre the very desirable properties of strength and toughness combined, and a number of strategies have been proposed to create a synthetic material that mimics this brick and mortar structure. Most of the proposed methods have involved a “ground up” strategy of assembling component parts, but this has only ever produced materials that have too high a proportion of adhesive and not enough solid bricks. Nacre itself is 95% aragonite, with only a tiny amount of adhesive holding everything together.

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Take it from the experts: oysters have been making better glass than us for over 100 million years. Still haven’t figured out how to make windows though. | Image: USEPA Environmental Protection Agency

A more recently proposed “top down” method involves a laser which carves into glass and fills the channels with polyurethane glue. This technique has created a material that strongly mimics the properties of nacre. It can be applied to glass or ceramic, both strong materials that are normally limited by their brittleness. By treating them with the polyurethane, scientists have created composite materials that have 700 times the toughness of the original glass!

Biology has been evolving materials for millions of years, to make structures for protection, support, buoyancy, cutting and grinding food, even building organic homes. Whereas slow evolution in the natural world means that each material has tailored properties making it the best choice for different functions, as humans we apply a relatively narrow range of materials to a very broad range of uses. As some materials become depleted, and others face environmental issues, it is vital that we explore other options, and tapping into the wisdom of nature seems like a good place to start.

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Natural Cycles: Part 1 – The circle of life and waste

By Anwen Bowers

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Circulation patterns in the North Pacific have created a vast plastic continent | Image: Steven Guerrisi

The Great Pacific Garbage Patch is a vast area in the Pacific Ocean where huge amounts of plastic and other slow-to-degrade waste has accumulated over the past half century. Rubbish from all the rivers in North America and Asia gathers here and then becomes trapped by the swirling waters of the North Pacific Subtropical Gyre.

The plastic has nowhere else to go, and so it circles around the oceans, breaking down into smaller and
smaller pieces; small enough to be consumed by the plankton, fish, birds and mammals of the Pacific Ocean. This poses a huge environmental threat, and it is a result of the linear processing of waste that is a uniquely human phenomenon.

In nature, everything is processed in cycles *cue famous Disney soundtrack*. As animals feed, the basic building blocks of life are passed up the food chain, and when the top predators die or defecate, the cycle starts again. Every single atom in our bodies has already passed through a number of incarnations, already been part of an ant or a daisy or a rock, and has the potential to become so again.

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They may look sinister, but vultures are nature’s recyclers; they are vital in many ecosystems | Image: Hugh Lunnon

Many organisms have carved out an ecological niche for themselves facilitating this cycle. Animals like vultures and dung beetles may not have the most glamorous rep, feeding as they do on dung and rotting corpses. But in so doing they remove a source of harmful bacteria and disease, turning it instead into bioavailable nutrients, promoting growth, habitat, and life. Unglamorous it may be, but an invaluable service nonetheless.

Where nature operates on complex, closed systems that generate zero waste, humanity tends to operate on a linear system. In this system, materials are processed into products that are useful for a time, but once they reach the end of their life span the waste is packed into crevices in the earth’s crust, or swept into oceans, never to be useful again.

This is unsustainable not only because these endpoints will eventually become saturated, but also because by taking the materials out of circulation, we are effectively putting an end to their reincarnation cycle. The more stuff that is floating in the Great Pacific Garbage Patch, the less stuff we have to use, and logic follows that we will eventually run out.

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Turning empty cardboard boxes into gourmet dishes: restaurants could have a lot to gain from the circle of life | Image: Lebensmittelfotos

Luckily, more and more business models are starting to see that that by following nature’s example they can simultaneously increase productivity, whilst decreasing harmful output. Cardboard to Caviar is an initiative set up by the Green Business Network (GBN) in West Yorkshire. Inspired initially by the problem of waste cardboard packaging from the restaurant industry, GBN’s solution was to collect the cardboard, shred it and sell it as bedding for horses.

A good solution, but what about the waste that then came from the stables? GBN started to collect that too, feeding it into giant composters, where the cardboard and manure were broken down by worms. The worms, in turn, are fed into GBN’s fish farm, where they are eaten by sturgeon, which produce caviar that is sold…to the restaurant industry!  

The number of businesses that process waste into something useful appears to have increased exponentially over the last few years. They’re turning chopsticks into furniture and plastic bags into bricks.

However, a word of caution: Whilst these examples should be credited for their innovation in extending the life of waste materials, they are still, in essence, linear. The risk is that whilst storing plastic in bricks is better than storing it in the ocean, we could ultimately also be storing up the problem for future generations. Plastic, in particular, can only be recycled into a useful product once; any further processing deteriorates the quality too much.

To effectively transition into a low waste society, there also needs to be a parallel shift towards sustainable, natural materials that can either be cycled in themselves or converted into new materials, continuing the circle of waste.

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Design, Naturally: Wasps take the sting out of brain surgery

By Anwen Bowers

“I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of caterpillars …”

This statement from Darwin is often quoted in discussions about his changing relationship with religion as he developed his theory of evolution. 150 years later, the ichneumonidae in question are taking a step towards shedding their demonic reputation by inspiring a new approach to neurosurgery.

| Image: Sean McCann
Pretty deadly. We could look at ichneumonidae ALL DAY.| Image: Sean McCann

The ichneumonidae are a subfamily in possibly the largest group of animals in the world – the parasitoid wasps. Estimates of the total number of ichneumonidae species alone reach up to 100,000 – more than all the vertebrate species in the world. The wasps gain their name because they brutally kill their host species, as opposed to parasites which drain the resources of an organism without causing significant harm. Indeed, life histories of the parasitoid wasps are close to the stuff of nightmares.

The extremely high diversity of ichneumonidae has arisen because each species of wasp has evolved to target just a single type of prey, and to do it as efficiently as possible. Each species is distinguished by its specialised weaponry or tactics that allow them to tackle their prey in their niche habitat or lifestyle. For example, Lasiochalcidia igiliensis’ chosen host is the antlion larva, a ferocious predator in its own right with vicious jaws that it uses against a range of arthropod prey, even spiders.

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A badass Antlion larva clearly has only one thing to fear. Fear of L. igiliensis itself. | Image: Larah McElroy

The seemingly fearless L. igiliensis has been observed to bait the antlion larva, encouraging it to attack the wasps itself. At the point of attack, the wasp will use its powerful legs to prise the jaws of the antlion open, whilst simultaneously depositing an egg into the antlion larvae’s throat. There the egg will incubate, feeding on the antlion from the inside, until the time for metamorphosis comes. At this point the wasp will burst out from the antlion, not unlike the infamous scene from Alien.

Strategies in other species include a fibrous mesh that traps air allowing the wasps to dive down and reach caddis fly in their underwater habitat, and a hormone invisibility cloak that allows the wasps to live within an ants nest, even up to adulthood, without detection. These guys are the Q Branch of the insect world.

M. macrurus prepares to drill. | Image: Evan Kean
M. macrurus prepares to drill. Just look at that ovipositor. Stunning, and inspiring… | Image: Evan Kean

Here at Rising Ape we can vouch from experience that great ideas happen when you put a bunch of scientists from different backgrounds in a room, and maybe give them a bottle of wine. This seems to be what happened in the case of Dr Ferdinando Rodriguez y Baena, a medical engineer who found himself inspired by a serendipitous dinner party conversation with zoologist and biomimetics expert Julian Vincent.

Vincent described how the parasitoid wasp species Megarhyssa macrurus, is able to use her egg laying tube to drill down into tree bark, where she deposits her eggs onto the larvae of the pidgeon tremaz horntail (how did this come up as a topic?! Over dessert?). This is possible thanks to a complex structure of three tubes that can bend and flex as the wasp drills, allowing her to position her eggs with pinpoint precision.

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The three parts of this needle echo the ovipositor of the drilling wasp and give it unparalleled flexibility. | Image: UCL

This elegantly specialised structure gave Baena the idea for a new style of needle that mimics the ovipositor. The design allows surgeons to control and manoeuvre the needle inside the patient, navigating around sensitive and fragile parts of the brain. This minimally invasive surgical procedure could even allow surgeons to deliver drugs to very specific areas in the brain, potentially treating diseases such as brain tumours and Parkinson’s. By saving lives for a change, the ingenious ichneumonidae wasps could be about to improve their reputation.  Who knows, even Darwin may have approved.

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Design, Naturally: Sharkskin V Superbugs

By Anwen Bowers

Antimicrobial resistance is one of the biggest challenges faced by the healthcare industry. The evolution of superbugs such as MRSA is evidence that the arms race between antibiotics and bacteria is not a sustainable strategy for preventing infection and keeping patients healthy. Bacteria are able to make infinite changes to their DNA, but there isn’t an infinite supply of new drugs available to target them. Scientists looking for alternative methods to tackle the spread of disease causing bacteria have turned to the natural world for inspiration.

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Opens doors, spreads diseases, can be opened by velociraptors. | Image: Public domain

Bacteria in hospitals spread through contact. If a person touches a surface that hosts bacteria, they can pass it along next time they touch a piece of equipment, or a patient. So could making surfaces inherently resistant to bacteria be an effective way of stopping the transfer and spreading of disease?

Traditional approaches to keeping surfaces sterile involve using some sort chemical agent, for example treating socks with silver to keep smelly feet at bay (equally effective against vampires). The disadvantage of chemical treatment is that protection is short lived, and needs constant renewal. Research suggests that silver nanoparticles in socks last not much longer than a few washes, as the silver is rinsed out into the environment where it becomes a poisonous threat to wildlife.

In a paradigm shift in strategy, scientists have proposed a new mechanical approach to keeping surfaces clean. Taking inspiration from the sea, they want to develop a texture that prevents bacteria from spreading by discouraging microbes from settling in the first place.

dirty boat hull
Hull is filthy. The boat’s hull that is. | Image: Glenn Batuyong

Place almost anything underwater and it won’t be long before a thin film of green slimy phytoplankton will start to settle. This plankton is the trigger for a chain reaction of settlement, as larvae of adhesive animals such as anemones and barnacles will soon follow. This has long been a problem for the shipping industry as fouling like this on ship’s hulls creates a huge amount of drag, slowing down the vessel and adding fuel costs. Even whales, despite their constant movement, will succumb to the nuisance of barnacles and parasites.

But scientists observed that sharks remain clean and crust free, even into old age. For a long time it was thought that sharks move too quickly through the water to give anything any time to settle. Closer inspection of the surface of their skin provided an alternative answer. Sharks are covered in specialised scales called dermal dentacles.

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Sharks: Creating the worst place for bacteria to hang out for 100 million years | Image: Pascal Deynat/Odontobase

Dentacle means “small tooth”, a name derived the dentine tissue from which they’re made and the same found in your teeth. Dermal dentacles are highly textured, and when meshed together they form an extremely complex surface, full of micro mountains and canyons. This surface appears to be too unstable for any bacteria to settle and establish a community effectively.

Without the base layer of microscopic organisms, the bigger problem of larger, fouler organisms cannot develop, and the shark remains clean and smooth. This evolutionary advantage then helps the seas’ top predators move swiftly through the water in pursuit of their prey.

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‘Phelps who? Bet I’m cleaner and faster.’ | Image: Mark Conlin

Shark skin is already well studied, and has inspired a range of products, famously the Olympic grade swimwear that can reduce drag and shave milliseconds of a swimmer’s time. To use it as a surface for hospitals was the idea of Anthony Brennan, founder of the company Sharklettm , who have trademarked a textured pattern based on the structure of sharkskin. The company claims that Sharklettm surfaces harbour 94% less bacteria than standard worktops and equipment.

Installed in places such as drawer handles and even surgical equipment, Sharklettm could be a cost effective way of reducing the spread of bacteria, as well as use of antiseptic and not to mention the time staff spend cleaning surfaces. What has evolved over millions of years could be a solution to a very pressing 21st century issue.