These animals’ ability to control light renders them almost invisible By Jasmin Fox-Skelly
We’ve all heard of squid and octopus using pigments to blend in with their surroundings, but what about becoming completely invisible? To become actually see through, and appear as if you aren’t there, you need to either allow light to travel through you unimpeded, or bend light around you - so that none reflects back at an observer. It’s a tricky task, but some animals are almost there.
In the ocean animals have two choices if they want to hide. Creatures that live in the deep ocean close to the seafloor can blend in with sand or rocks, or hide in coral. In the deep ocean it is often pitch black anyway and predators lack eyes, so being invisible is not necessary.
Animals that live close to the surface and want to hide can produce dazzling displays of light in a process known as bioluminescence, confusing predators below who think they are looking at dappled sunshine hitting the water’s surface. Animals that live in midwater though have neither of these options. This region is known as the pelagic zone, and it also happens to be where most invisible animals live.
Perhaps the easiest way of becoming invisible is by being transparent and letting light travel completely through you. In open oceans, which lack structures to hide behind, being transparent is a great way of hiding from all viewpoints and angles. It’s so popular in fact that transparency has independently evolved multiple times in completely unrelated animals.
One such animal, the glass octopus (Vitreledonella richardi) is so named because it is almost completely transparent. The gelatinous creature can grow up to 45cm (18in), if you include the tentacles. It lives 300-1000m below the surface in tropical and subtropical waters across the world, and is almost completely invisible to predators except for its digestive system, optic nerves and eyes.
But what’s the point in making your whole body transparent, if the eyes and guts are still visible? Even worse, these organs will cast shadows on the seafloor below, making them more visible to predators. Eyes need to absorb light to function, so it is not possible for them to be transparent. Guts betray their contents, so unless an animal feeds on transparent material, they will be visible. However the octopus, and all hosts of transparent creatures go to great lengths to disguise these opaque organs. The glass octopus (Vitreledonella richardi) for example has very elongated eyes which reduces its peripheral vision, but minimises the shadow it casts below - making it less likely to be detected by predators hunting from below. There is also some evidence that it orientates its body in such a way so as to minimise its shadow.
The glass octopus is not the only transparent animal to come up with an ingenious way of disguising its eyes. Many transparent molluscs camouflage their eyes with mirrors, as mirrors in the open ocean reflect only more ocean and so are invisible.
The glass family of squid, of which there are about 60 species, are almost entirely see through. They live, again in the pelagic region of oceans around the world, between 200 and 1000m below sea level.
Although their bodies are entirely transparent, their large eyes are opaque, which is a problem as predators swimming below can easily see the shadow they cast. However the glass squid (Cranchiidae) uses a clever form of camouflage to hide them. It uses photophores - organs beneath its eyes - to produce light in a trick called counter-illumination. This light looks very similar to the sunlight filtering down from above, so it makes the squid completely invisible to predators swimming below it. However the light could make the squid very conspicuous to viewers looking at it from other angles. Rather than an invisibility cloak, the glowing light could act like a beacon drawing predators to it.
Researchers from the University of Pennsylvania found that the squid’s photophores are amazingly able to match the amount of light they produce to that coming in from every direction, creating a sort of omnidirectional invisibility cloak.
This genus, or group of marine planktonic polychaete worms are almost completely transparent, making them very difficult for predators to see. Paradoxically at least 11 species in the group can also emit bright luminous colours. Most tomopteris worms glow blue, but one species, Tomopteris nisseni can produce yellow light and is one of only few such creatures on the planet to do so.
Some tomopteris worms can even distract predators by releasing a glowing part of their body called a parapodia, making the predator chase after the dispelled body part rather than the worm itself.
A salp is a completely transparent barrel shaped creature which swims and feeds at the same time by pumping water through its gelatinous body. They filter out the phytoplankton in the water to feed on. Although they look a bit like jellyfish they are actually more sophisticated and are closely related to fish and vertebrates - they have a heart and gills and can reproduce sexually.
Salps have a fascinating life cycle. For part of it they live by themselves, but they then clone themselves and form long strings and other shapes of connected organisms. Individual salps synchronise their swimming by communicating with one another via electrical signals.
Sometimes being transparent isn’t enough, and organisms need other tricks up their sleeve to remain invisible. This is certainly the case for the Hyperiid, a little crustacean bearing a resemblance to a shrimp. They are able to hide from predators by being transparent. However that only gets them so far. A plane of glass is also transparent but you can still see it if you shine a light on it, as the light is reflected back. This is a particular problem in the ocean because many predators use bioluminescence as a searchlight when hunting for prey.
A recent study suggests there is more to the hyperiid’s ability to hide than simple transparency. It turns out they are using a kind of nanotechnology to interfere with and bend light, cloaking themselves and almost rendering them invisible. The scientists used a scanning electron microscope to closely analyse seven species of hyperiids. They found that the legs of one species were covered in tiny nano sized hair-like protuberances.
The body of this species, and six others were also covered in nano sized bumps or spheres ranging in size from under 100 nanometers to around 300 nanometers. The tiny size of the bumps could minimise light scattering and the scientists found that a combination of both nanostructures - the bumps and the hairs could reduce reflectance by as much as 100 fold. The weird thing is that the researchers think these spheres could actually be bacteria.
Japetella heathi and Onychoteuthis banksii
The squid Japetella heathi and the octopus Onychoteuthis banksii also have a novel trick up their sleeves when it comes to invisibility - they can quickly switch from being transparent to a reddish brown colour.
They both live in the Pacific Ocean between 600-1000m deep – known as the mesopelagic zone. Although being transparent helps a lot with invisibility close to the water’s surface, as diffuse sunlight from the surface passes straight through transparent tissue, when you shine a light directly on something that is transparent, it suddenly becomes very visible.
Unfortunately this happens quite a lot in the deep sea, where predators use light-emitting organs called photophores like a searchlight when hunting. Prey at these depths are often red or black so that they reflect as little blue light as possible. Japetella heathi, an octopus, and Onychoteuthis banksii, a squid, are able to switch between both, but how do they do it? Both species’ skin contains light sensitive cells called chromatophores. The cells contain a dye, and when they detect light they immediately expand and release the pigment.
Sea Sapphires (Sapphirina) are ant size creatures that live in warm tropical and subtropical seas. They belong to a group of crustaceans called copepods. Different species emit a range of brilliant iridescent colours, from vivid blues to reds and golds.
What is remarkable about them is that one second they can shimmer brightly and the next they appear almost to disappear and the way they do this is fascinating. Their skin, or cuticle cells contain tiny crystal plates arranged in a hexagonal honeycomb pattern. The crystals contain guanine, one of the four bases that make up DNA. The crystal layers are separated from each other by a soup-like fluid called a cytosol.
A team of scientists found that the although the layers of guanine crystals are always exactly the same thickness – 70 nanometers, the thickness of the cytosol between the layers varies from 50 to 200 nanometers. It is this variety which determines the colour of the sea sapphire. Thicker layers of cytosol lead to longer wavelengths of light being reflected, which make the copepod look red or magenta.
The colour also depends on the angle of light which strikes them. As the angle becomes smaller and smaller, the wavelength of reflected light becomes shorter and the colour more violet. If the angle becomes small enough then the reflected light is in the UV spectrum, which means that we can’t see it and the sea sapphires disappear. The researchers found that light which hit the crustaceans at a 45° angle effectively caused them to become invisible.
All of the transparent animals discussed so far have lived in the sea, and there’s a good reason for that. To be transparent you need to be made up of stuff that neither absorbs nor reflects light. This is a difficult task for plants and animals that live on land because there is such a large difference between the refractive index of living tissues and air. The refractive index of a material describes how quickly light travels through it. Light travels fastest in a vacuum, and generally speaking the denser a material, the longer light takes to travel through it and the greater its refractive index will be.
As biological tissue is so much thicker and denser than air, when light waves go from travelling through air to body tissue, they slow down. This causes light to change directions and scatter, causing reflections that make the animal more visible.
In the sea there is less difference between the refractive index of water and biological tissues, so transparency is an easier task, hence why there are so many ‘almost’ invisible animals. Another reason you don’t find many see through animals on land is because organisms need pigments like melanin to protect them from UV radiation from the sun.
However there are some exceptions to the see through rule. One is the glasswing butterfly (Greta oto) which lives in Central America.
Although not all of its body is see through, its transparent wings make it difficult for predators to track it during flight. To look at how the butterfly achieves its transparency, scientists examined their wings under an electron microscope. They found tiny nano sized bumps called nanopillars which were scattered randomly and had different lengths. It seems that the random size and distribution of the nanoscale structures help the butterfly minimise reflections from its wings. The nanopillars interfere with rays of light hitting the wing, causing most to pass straight through rather than bouncing back.
Another exception to the rule is a translucent snail (Zospeum tholussum) that was discovered in the deepest cave in Croatia. Scientists from Goethe University, Frankfurt found the see through mollusc living 980m underground in the Lukina Jama-Trojama cave, in a chamber full of rocks and sand with a small stream running through it.
The snail belongs to a genus of miniature land snails that are found in dark, underground caves, and which are unable to move by themselves. Researchers believe they use running water from streams to transport themselves.
However even though it is translucent, the snail is still fairly visible, highlighting just how difficult it is for land animals to achieve what those in the ocean do.
Shouldn’t policy be based on evidence – not the other way around? By Amy Orben
The future seems rosy for Jeremy Hunt. In his newest letter to social media firms, he envisions a future where every child gets a state-imposed and universal social media limit, similar to the alcohol units recommended by government. After a child surpasses a set cutoff point, their social media access is stopped for the day. Hunt makes it seem easy, practical, and better for children and parents alike.
There is just one glaring problem. This drastic policy still needs the scientific evidence to back it up. Hunt announced yesterday that his chief medical officer will be taking charge of this. Well, as a scientist working in this area, I can tell Dame Sally Davies now: the evidence this policy needs doesn’t exist. If she is not willing to ignore large parts of the scientific literature or exaggerate a minority of low-quality studies, her job to find the amount of “science” to back up such significant state intervention will be impossible. And, to insert an important side-question, shouldn’t policy be based on evidence – not the other way around?
Scientists examining child development and technology use have for years been trying to raise awareness of the misguided debate around children and screen time; a debate often devoid of significant scientific evidence. The common comparison between screen time and drugs like alcohol indicates a misconception many politicians and journalists share. Screen time isn’t a chemical that, when ingested, causes concrete physiological changes that can harm the body and cause long-term dependency. It is a diverse and ever-changing part of daily life.
First, there is no concrete evidence that supports the common view that technology use is inherently harmful. The evidence base is low-quality and riddled with issues including biases in reporting and small effect sizes. Recent studies that got large amounts of press coverage and demonstrated a negative link between social media use and wellbeing also evidenced that knowing a child’s social media use will only help you predict 1% of their depressive symptoms. That is an extremely small effect and raises questions about whether our debate to improve teen mental health is misplaced. Other research, for example, shows that the positive effects of a good night’s sleep and regular breakfasts on wellbeing are three times stronger than the negative effects of technology use.
Screen time guidelines need to be built on evidence, not hype
Notwithstanding this, the debate is oversimplifying the sheer diversity of technology and social media use. No individual’s social media use is the same, with the content and context changing daily. It is therefore impossible to conclude what the universal effects of “social media use” are. Want to know the true effect of X minutes of social media use on a child? The answer will almost always be “it depends”: it depends on the kind of social media use, the usage patterns, the child’s motivations and the context. Until we accept this inherent complexity in scientific research, policymaking and media coverage, our efforts to help children and teenagers and tackle societal changes will be misplaced and inefficient.
So, if the Department of Health wants to roll out large-scale policy changes, go ahead, but please do not try to make it sound like “science” backs it up.
Schools should play a bigger role in preparing children for social media's emotional demands as they move from primary to secondary school, England's children's commissioner says.
Anne Longfield said she was worried many pupils at that stage became anxious about their identity and craved likes and comments for validation.
Her study said children aged eight to 12 found it hard to manage the impact.
The government said it was working with schools on online safety education.
The report into the effects of social media on eight to 12-year-olds claimed many children were over-dependent on "likes" and comments for social validation.
It said children approach a "cliff-edge" as they move from primary to secondary school, when social media becomes more important in their lives.
The report spoke to 32 children in eight focus groups, aged eight to 12, and found some saying:
Ms Longfield called on schools and parents to prepare children emotionally for the "significant risks" of social media as they move schools and meet new classmates - many of whom have their own phones.
"It's really when they hit secondary school that all of these things come together," she told BBC News.
"They find themselves chasing likes, chasing validation, being very anxious about their appearance online and offline and feeling that they can't disconnect - because that will be seen as socially damaging."
Although most social media platforms have a minimum age limit of 13, the report said three-quarters of children aged 10 to 12 already had accounts.
'Avalanche of pressure'Ms Longfield said she was surprised at how children viewed social media differently as they grew older.
Younger children use social media for "fun family reasons" but it becomes an "avalanche of pressure" by the time they get to secondary school age, she said.
Parent Trevor said his 12-year-old twin daughters had moved schools as a result of the pressure from social media, but admits they "can't walk away" from it.
He told BBC Radio 5 Live: "I can't say to them 'you can't use that', when I use it".
He said teachers lacked the skills to educate children and said the approach by politicians was "disappointing".
Izzy, a 17-year-old pupil from Bristol, said she was "judged at every corner" on social media, after first seeing the platforms being used by her older cousins.
"Being exposed to all this adult stuff happens very quickly," she told 5 Live.
'Emotional rollercoaster'Ms Longfield said social media provided "great benefits" to children but was also exposing them to "significant risks emotionally".
She called on the government to introduce compulsory digital literacy and online resilience lessons for year six and seven pupils, so that they learn about the "emotional side of social media".
Parents should also prepare their children, she said, by "helping their children navigate the emotional rollercoaster" of the negative aspects of social media.
By Janis B. Meredith is a youth-sports parenting blogger, podcaster, and parent coach. She helps busy sports parents by providing resources to guide them as they strive to give their children a positive and growing youth-sports experience. Her book 11 Habits for Happy and Positive Sports Parents can be found on Amazon.
Your child has worked super hard back at school and has made the team. Now, parents, do you have what it takes to sit on the sidelines and watch?
Being a sports-parent spectator is not as easy as it looks. That’s your child out there, running around on the court or field and you are very emotionally invested in his or her happiness and safety.
But if you really want your child to have a good youth-sports experience, you must understand what it means to be their cheerleader. Here are 5 tips to help you:
Stay seated. If you are a parent who paces the sidelines, hovers behind home plate, or stands up and yells from the bleachers, you are most likely distracting your child from playing her best. When you are not hovering, pacing, and showing your emotions in a myriad of other ways, I’m pretty sure your child will relax and even play better. Seeing and hearing your tension will only make her more tense and no athlete can do her best when she’s worried about what her parents are thinking.
Of course, every now and then — when the game is tight or your child is facing a big challenge — you may understandably feel the need to stand up or pace a bit. Just don’t let it be a distraction to your child.
No coaching please. You have entrusted your child to the instruction of his coaches. Let him or her do their job. At home, it’s okay to discuss strategies to help her become a better player, but this should not be done from the bleachers. Your child needs to focus on the game and on what his coach is telling him; not on you yelling instructions.
Keep your cheering positive. Acknowledge a good play or smart choice, but refrain from shouting Don’t messages. Don’t strike out! Don’t miss the tackle! Don’t mess up this shot! Yelling these types of instructions causes your child to focus on the Don’t instead of the Do.
Be intentional on the car ride home. It’s easy to get carried away in the emotion of the game and start pointing out your child’s mistakes and what she needed to do better. Instead, let the car ride home be a place where your child drives the conversation. If she has questions, then answer them, but if she doesn’t want to talk about it, then let it go. One remark such as “I loved watching you play today” is really all that she needs to hear.
Support, don’t push. Although there are gentle and positive ways to help motivate your kids, the pushiness that many sports-parents practice is not what being a cheerleader means.
A cheerleader is one who leads by cheering, not by nagging, cajoling or forcing their opinions on someone. And quite honestly, those methods rarely produce the long term results that will help your child have a positive and lasting youth-sports experience.
The best way to cheer your kids on to reach their potential is by being the type of sports parent who sees the big picture value of sports and the lessons they can teach kids. Having that perspective allows you to focus on what’s really important in the long run, and that will free you up to be the cheerleader your child needs.
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This week sees Nestlé Professional chefs Darren Chapman and Justin Clark cook up a storm by giving children a taste of making appetising food and creating some art on a plate at two schools.
In addition to that our chefs will give the students a unique insight into life as a chef and why it is a career destination of choice.
Approximately 90 students from Burnley Road Academy in Halifax and St Francis of Assisi in Crawley will take part in cooking sessions this week, which will include the children participating in the cooking and presentation of meals, making it fun and interactive.
This follows Nestlé’s ongoing activity to encourage children to be creative and adventurous with food which will enable them to discover new foods they may otherwise avoid.
This event is part of the Nestlé Healthy Kids Programme which is delivered by PhunkyFoods in the UK, which aims to improve the awareness, knowledge and effective practice of healthy eating and physical activity in primary school children.
For more information on the Nestle Healthy Kids Programme, please visit
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One in three gets bullied, and about half of those kids' parents don't know it's happening. By Colin Lecher
It's bad enough that they have to avoid milk and peanut butter and jelly sandwiches. A new study reveals that kids with allergies also get picked on at lunch.
About 8 percent of children in the United States have food allergies--to peanuts, shellfish, eggs, etc.--and a study from researchers at the Icahn School of Medicine at Mount Sinai found that about a third of those children are bullied. Their study appeared online December 24 in the journal Pediatrics.
The researchers surveyed 251 pairs of parents and children on visits to allergy clinics and had them fill out a questionnaire about incidents of bullying and overall quality of life. Sadly--but maybe predictably--the kids with allergies were getting bullied quite a bit. What's more surprising is that about half of the parents surveyed didn't know the bullying was happening, even when both they and their kids reported higher stress and lower quality of life.
The researchers suggest asking your food-allergic child if they're being bullied. Like allergies themselves, knowing the problem is the first step to avoiding it.
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