Of shiny, shiny, shiny beetles and leather…

In the left had spaniel’s lap – or almost in its lap – sits a comforting lump of labradorite. They neither growl at each other, nor fight.

Perhaps in spite of the appearance of being top-dog, the spaniel realises it is heavily outnumbered, for even if it could form a cross-mantelpiece alliance with its mirror-twin, its own half of the mantle shelf is rather packed by rocks of Labrador-ite nature. The far side, meanwhile, is dominated by pots of lustrous finish and collections of feathers and shells.

If there is an unifying theme – and I have to say that consciously, there isn’t, beyond a ‘I rather like the way these things look and they fit OK on the mantelpiece…’ sentiment – it’s that the halves, as a whole, evidence my fascination with iridescence.

Oil-caressed puddles on dank winter Mondays, spectral rainbows arching in bubbles, the nacreous lure of shells; all entrance. Luminescence in clouds, the shifting sheen of old lustre-wear, the sudden flash of a jay’s wing… I peer, transfixed, whispering ‘shiny…’

To shine, in itself though, is not enough; no, the beauty of iridescence is that it has to be crept up upon… flirted with, with a sideways glance… a coquettish tilt of the gaze. Iridescence is coy, sharing its loveliness only with those prepared to look with hope. The beauty of iridescence is truly in the eye of the beholder.

Those accustomed to my blogging will, by now, no doubt be expecting an etymological exploration of ‘iridescence’, followed by an explanation of the phenomenon – Jude’s picky-paedia. Well, hating to disappoint, I can tell you that its Greek root lies in Iris, the personification of the rainbow who also gave her name to the coloured part of eyes and the fabulous early summer flowers… although picky gardeners will no doubt add that irises have rhizomes, not roots.

Picky anatomists (and let’s face it, if you’re an anatomist, can you really afford to be picky? I mean making friends can’t be easy, can it?) will meanwhile add that the part of the eye known for its iridescence is not the iris but the tapetum lucidum (L. ‘bright tapestry’) – a reflective membrane which lies behind some creatures’ retinas, bouncing light back like a mirror. In so doing, it both improves vision in low lighting and producing the characteristic ‘eye shine’ we associate with creatures of the night.

But given that there’s a price for having better nocturnal vision – apparently possessing a tapetum lucidium compromises some other elements of visual acuity – it puzzles me that many diurnal species not known for their all night parties also have tapeta lucida – e.g. dogs, cows, goats and sheep… Crepuscular rabbits, on the other hand, in spite of their fondness for the twilight hours and association with ‘bright eyes, burning like fire’ – have no tapetum lucidum – just a nasty case of conjunctivitis, perhaps? Humans, of course – also being tapetum lucidum-less – need sheep’s eyes to glow in the dark – for how else could we count them jumping over gates once we were tucked up in bed?

Creatures feline, meanwhile, have been immortalised thanks to their tapeta lucida – both in the prowling form of William Blake’s ‘tyger tyger burning bright’ and by Halifax inventor Percy Shaw, who, in 1934 patented the Catseye™.

Conflicting stories exist concerning the source of Percy’s inspiration – including the ghostly gleam of tramlines in the dark, the efficacy of reflective road signs and of course the shining eyes of a cat – sat variously in the road, on the verge or on a fence – which caused him to swerve and saved his life one foggy Yorkshire night. Yet in spite of the unquestionable brilliance of his invention, it is debatable whether it would have made him quite-as-rich-as-quick had it not been for the blackouts of the Second War and Junior Minister Jim Callaghan’s decision to order catseyes for the whole country.

Percy, we are told – a man who had experienced considerable poverty in his youth –  did not allow wealth to change him much, his main indulgences being Worthington White Shield, pickles and watching the wrestling. In fact he kept four television sets constantly on in his living room – one attuned to each of the then three channels, with a fourth for BBC2 in colour… one way of resolving the channel-hopping challenge in the days before remote controls…

And indeed it’s an arrangement I may myself resort to in my dotage, for I realised the other day that I no longer know how to select a channel of my choosing.

In my youth it was easy; you twisted the on-off knob until it clicked and then, once the TV had ‘warmed up’, you stabbed at one of just three buttons with a confident finger.

Sometimes – quite often in fact – the TV warmed up a little too much, and there would be an explosion at the back of the set. On these occasions, Paul Turner would be summoned, whilst anxiety spiralled in our normally calm household.

Yes, to you Paul Turner may be a nobody, but to children anticipating resurrection he was a demigod, capable of dispensing either delight via speedy repair or despair by declaring that he would have to take the set ‘back to the workshop’. Please, oh please Paul, don’t say those words… Spare sets – unless you were Percy Shaw – were unheard of in those days and the TV-less evenings stretching ahead felt as dark as the tube itself.

My father’s anxiety revolved around how much the repair would cost, whilst my mother would hover nervously clutching a threadbare old vest, fretting to get at the dust and cobwebs displayed, disgracefully, by the TV’s removal. Only Grampa remained calm, his essential viewing boiling down to the Welsh hymn singing on Sunday night which, at a push, you could get on the wireless. Failing that, we could always gather round the harmonium in parlour… Please, oh please please please Paul, don’t say those words…

There was one occasion however when Paul Turned appeared standing not next to the television but on the television. No, not practicing a novel form of repair drawn from the ‘give it a kick’ school of fixing – he was actually on TV, one of the contestants on ‘The Golden Shot’.

Those of you old enough to remember this Sunday tea-time game-show will no doubt understand how demigod was quickly elevated to god when I tell you that Paul actually got the Golden Apple. Those of you younger might want to know that the series involved Bob Monkhouse and blindfolded, crossbow-firing cameramen… but that makes it sound much more promising than it actually was… in retrospect.

Paul’s days of deification were however short lived – both tastes and times move on and TV rental – courtesy of Rediffusion – moved in, allowing instant replacement sets at no extra charge, anxiety-free callout for all but my mother and our first remote control, an object of such power that panic set in should it disappear from view. In later years I coped fine with the two remotes necessitated by the advent of video cassette recorders and even grew confident with Ceefax…

Today’s technology however – involving different remotes for the TV, the VCR, the DVD and CD players, the Sky box, the Wii box, the Blue Ray, the amp, and the ‘thing’ that records straight onto some mysterious internal disk – leaves me swimming in powerlessness. If by fluke I actually manage to turn the TV on, it flashes up messages demanding to know which input source I require. I blink back at it and scowl. There’s an order in which you turn things on – or it won’t ‘throw up the options’, so I’m told… and even if I accidentally get the picture I want, getting the amplifier to play the associated sound as opposed to last night’s DVD – still lodged somewhere in the stack of mysterious black boxes – is an additional challenge… Move over Percy – and after you with the pickles, please…

Percy, incidentally, is also the name of one of the contributors to my feather collection. A talkative yet intuitive parrot named after Bysshe Shelley, he lives with Nick and Michael at Plas Tan-yr-Allt, a magical little hotel nestling in woodland high above the Glaslyn Estuary in north Wales. Once home to P.B.S. himself, I notice it’s been named by the Guardian as one of ‘10 Sexy British Boltholes’… and am left feeling rather guilty for letting down the tone of the establishment by my determined, repeated visits…

Michael and Nick are charming, but I’ve had a couple of run-ins with Percy – the first one when I mistook his dish of raw mange-tout for a healthy bowl of nibbles, the second when he mistook my lovely long fingernail for a nutshell and decided to find out what lay inside… My finger was, admittedly, being poked through the bars of his cage at the time and the fault – and the blood – were all mine. Which of us squawked loudest at which incident it’s hard to say, but my language under provocation was far, far worse than his…

In fact I crept away the next morning hoping against hope that Percy needs to hear a word repeated many, many times before he is able to add it to his repertoire – and must read the Guardian small-print to check they’ve not based their ‘sexy’ label on the fact that the house parrot talks dirty…

The other plumage contributors are nameless, long flown by the time I happen upon a souvenir of their passing – not too many of them literally, I hope. They include ducks, seagulls, a robin, siskins, bluetits, a woodpecker and, most recently, one or more magpies…

Regulars in the park next to my old place of work had grown accustomed, I suspect, to the sight of me striding around, stooping every now and then to coo and pick up a feather. The Spanish Civil War memorial, the notice on the gates prohibiting drinking and the occasional tramp emerging from the undergrowth on fine mornings announce it as a park well used by all strata of society, and people probably just nodded knowingly as they watched me head for the mental health drop-in centre where I was based. One or two, I suspect, will have added ‘poor thing…’

The park next to my new place of work however has a different feel to it altogether – it is bounded by posh parts of town, boasts a boating lake, botanical and ornamental gardens… has no chippy by the gates and no pubs within vomiting distance. The strollers have go-faster stripes and people running through it tend to actually be jogging rather than evading security guards from nearby stores.

I managed to wing it, I think, whilst still confining myself to gathering feathers which looked pretty from an upright position and my stoop-and-coo manoeuvres were all that were involved – but the recent discovery that not all large plain black feathers are plain black feathers added not only so many more potential treasures to be examined but also an odd, twitchy, tilting action to their collection – first of the feather – then of my head – then of the feather again – often followed by a small whoop of delight.

It took though an incident involving a tall hedge, a short, elderly gentleman and a begging conversation I was actually having with a jay (‘come on, give it to me… you know you want to…’) to convince me that I’d better confine myself to the hospital grounds – lest I find myself confined to them.

Happily the local magpie population seem to delight in hopping round the maternity unit, waving invisible skeins of pink, blue and lemon wool through the windows – and so it is that I have a growing collection of iridescent feathers – black viewed square on, but creep up on them… tilt them and… Oooooh…

The actual mechanisms of colouring in birds are complex, with two different sorts of effects combining to produce the bird we ‘see’. First of all there’s pigment colouration, which is due to ‘stuff’ that’s actually there, present in the feathers. This sub-divides into three sorts of stuff – melanins, porphyrins and carotenoids….

The most common – melanins – are the badge of machismo in the world of birds. Manufactured in their bodies and related to dominance and aggression levels, they produce dark – black, brown and grey – colouration in feathers which provoke responses in both sexes… A male sparrow with a big, black bib will, for instance, be seen both as more threatening by other males and more attractive by females.

Posing the chicken-or-the egg question over the link between feather darkness and dominance led scientists to a surprising discovery though – birds which had their feathers artificially darkened suddenly saw their levels of testosterone shoot up – their colouring seemed to be triggering their hormones rather than vice versa – rather like a new outfit making us feel better… 

And melanins don’t only announce a bird’s toughness, they also act physically to actually ‘toughen’ the feathers where they are deposited, aiding both fight and flight. Many species of large flying birds for example – whose feathers are more stressed by flying and exposure to sunlight – have black tips to their wings… In fact I like to think of melanin coloured feathers as bikers’ leathers, both protective and making a statement…

Porphyrins – much rarer – in fact believed to be confined to owls – are also manufactured within their bodies, and produce reddish brown hues. They also – wait for it – fluoresce bright pink when exposed to UV light which – birds being able to see in the ultra violet spectrum – must rather put the ‘wow’ into owl from their nocturnal point of view.

(picture of saw-whet owl wing taken under UV light – courtesy of Ned Smith Centre for Nature and Art

Lastly come carotenoids. If melanins are the leathers, then carotenoids are the flashy silk shirts and loud ties of male bird display, producing vivid red, orange and yellow hues deeply attractive to female birds. How deeply attractive depends, interestingly, on the literal depth of the colour, its saturation being the major deciding factor in who gets first peck with the ladies.

Unlike the other pigment-based colours, carotenoids cannot be manufactured by birds and have, instead, to be gathered through feeding, either on plant material or on things that have consumed the plant material within which carotenoids are manufactured. The depth of a bird’s bright colouring is, then, directly proportionate to its ability to seek out food – a pretty good indication of its potential as a provider for offspring.

Consuming high levels of carotenoids does though take its toll, the by-products of a diet rich in them breaking down muscle tissue and reducing flying capability. Only the healthiest males can sustain their brilliance.

This of course leaves us with a bird kingdom populated only by red, orange, yellow, brown, grey and black varieties – or pink, if you’re an owl. So what of the bright blues and greens? The iridescence?  Where do they come from?

Well, they occur as a result of structural rather than pigment colour… i.e. instead of being due to a substance actually present in the feather, they’re what we perceive when light hits the feathers – a pigment of the imagination…

What happens is that the actual way in which the feathers themselves are made – their nano-level microstructures – lead to the light being broken down into its constituent parts.  Some structures will, at certain angles, produce the transient shine of iridescence. Others will simply absorb some wavelengths and reflect others back, leading to a more ‘all-over’ effect.

(utterly amazing image courtesy of www.glenbartley.com )

And sometimes both pigment and structural colours combine – e.g. a pigment yellow with a structural blue – to produce a brilliant green – as in Percy…

Occurrences of iridescence in general though – in bird, insect, animal, mollusc or mineral – cannot all be explained by the same structures or even optical effect, beyond the very broad statement of it being to do with the way light behaves when it hits certain surfaces.

Wikipaedia describes it as ‘multiple reflections from multi-layered, semi-transparent surfaces in which phase shift and interference of the reflections modulates the incident light (by amplifying or attenuating some frequencies more than others). This process is the functional analog of selective wavelength attenuation as seen with the Fabry-Pérot interferometer.’ And my guess is that if you understood a word of that, you probably didn’t need Wikipaedia to tell you…  

A far more illuminating explanation can be found at http://www.webexhibits.org/causesofcolor/15.html , along with some spectacular photographs of bubbles…

In at-first-glance dull, grey, Labradorite meanwhile, the iridescence is kindled by something known as the ‘schiller’ effect, caused by ‘lamella’ – i.e. plates or thin layers, formed within molten rock as it cools. Once solidified, the crystallised structure works in a similar way to a prism, refracting and slowing down rays of white light so that their wavelength is altered, producing the stormy flashes of blue, gold, violet and green characteristic of the stone.

It gets its name from the coastal region of Canada in which it was first reported by Moravian missionaries in the 1700s, where Aboriginal Eskimo legend explained how the Northern Lights lay imprisoned within the coastal feldspar until a warrior freed them with a mighty blow of his spear, leaving only their haunting imprint behind…

People who believe that rocks have an effect on human beings’ health – beyond hurting us if they drop on our toes – say that Labradorite helps to counter anxiety, depression and hopelessness. For me, each piece I encounter simply holds the same thrill as a secret panel which slowly slides to one side… a closed box which rattles; when I cradle and tilt this particular piece of stone, what brilliance will lie within?

My robin is looking a little green around the gills – or a bit pale at least – due to his annual moult. Little wonder perhaps – it is, after all, a stressful and energy-consuming task, shedding and re-growing each and every one of your feathers in strict bilateral order. I know it’s gross anthropomorphism, but I liken his behaviour at this time of year to that of a surly adolescent – quiet, skulking and sulky – and give thanks for his lack of doors to slam.

He has, this year at least, one reason to be cheerful – for Tig is dead. Only four weeks buried – beneath the orange blossom, in a spot she loved in life – I’m not going to write about her with sadness – but forgive me that I can’t write about her with happiness at the moment either – not just yet.

The morning of her burial an odd thing happened. I’d (mostly) cried myself out the previous night and was in grim ‘lets get this done’ mode. The final shovel of earth tamped down though and the large wooden owl hauled in as a weighty deterrent to grave-robbers, we paused, both to rest and in respect – although still too fragile to admit it to each other. I know it must just have been coincidence – and a gardener with a spade is, after all, a robin magnet – but at that very moment a cloud banked over the sun, both the seagull and crow started calling from afar – and in flew the robin.

What was truly odd though was that rather than flutter to me looking for mealworms – which is what he always always does – he perched on a branch directly above the owl – and the pussycat – and sang a short burst of sad, minor key winter song – in the middle of June. And then he flew away.

I mentioned, earlier, that the beauty of iridescence is in the eye of the beholder. I have begun to conclude the same of oddness.

The realisation dawned on me when this blog was but in its infancy – merely a twinkle of irid in my iris and pupil… on a train journey home.

It came on an Arriva train – the company that spawned the slogan ‘it’s better to travel hopefully than to Arriva…’ on one of their optimistically hopeless two carriage ‘services’ from Swansea to Milford Haven. I got a double seat – unlike the many standing – but found myself next to a young man from Aberdare and opposite a mother and son from Cambridge.

The Aberdarian – and I use the term advisedly, as I’m convinced they are a species entirely of their own – far from withdrawing in battery chicken style – chatted for the entire journey – of his girlfriend, her cooking skills and hopes for marriage, horses, his ambitions, the metre of ancient welsh poetry, politics and badger culling… and the English pair rose gamely to the challenge, responding politely whilst wearing that ‘we’re harmless really, please don’t eat us…’ look.

‘He was sweet but I’m sure they thought he was very odd…’ I recounted to Tom as he recued me from the station.

‘What have you got in your hand?’ he asked

‘Oh, a beetle…’ I replied – suddenly remembering that I’d walked off the train with my arm extended, my fist closed.

‘Why?’ he asked, reasonably enough…

‘Ooooh, it’s lovely – it’s iridescent – it was on my bag on the train – and I knew I needed it for my blog – but then it flew off – so I kept talking to it – in Welsh – and watching it… And when we were pulling in I grabbed it… I’ll let it go as soon as I’ve taken its picture…

‘It’s ok though… I explained to them all on the train what I was doing… and I think they understood… Well they seemed to understand why I keep wanting to dig up the cat and bring her indoors when it’s raining anyway…’

May your cats be dry and your oddness shine…

 

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~ by Jude on July 23, 2010.

2 Responses to “Of shiny, shiny, shiny beetles and leather…”

  1. “a pigment of the imagination…”
    groan..
    Laughing
    A wonderful and informative jaunt in the realms of Judeness.. I thank you..

  2. <<< blushes

    I know… and I didn't even say sorry…

    Sorry, lol…

    Good to hear from you again – and thank you for your reading and words 🙂

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